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ProGasMix FC - Manual

1. are t ta tiet eae ane m 34 5 4 Flowmeter einen nnns nnn trennt 35 5 5 B bbler refill itera te aep ree ens 35 5 6 Temperature controller programming eese 35 Technical specifications and 0 0 36 6 1 ProGasMix flow a aa 36 6 2 ProGasMix marking 5 200 38 6 2 1 The ProGasMix front panel markings and 38 6 2 2 The ProGasMix exterior markings and functions 38 6 2 3 The ProGasMix interior markings and 5 38 38 6 4 Other reference lists iere er ede etr eee ieee 39 6 4 1 Shipment contents ierit e 39 6 4 2 Included doculvients ooi eee 39 7 Material and safety reference 40 7 1 Reference to the EC Pressure Equipment Directory PED 40 7 1 1 Conformity Compliance and General 40 7 1 2 Desig 40 7 1 2 1 Genetalz ie eth etie 40 7 1 2 2 Design for adequate eene
2. eene 17 3 8 Learn the principles and terms of gases and mixtures 18 3 9 Startup and checks during initial operation first user operation training session 18 3 9 1 m 19 3 9 2 Initial settings 0 0 0 ennemis 19 3 9 3 erc 19 3 9 4 Flowmeters and overpressure bubblers sees 19 3 9 5 Leakage test tds det e berets met tds 20 3 9 6 Leakage identification and elimination 20 3 9 7 Leave the mixer with overpressure 0 nennen nennen 21 eir tert tete i 21 4 1 Use of software to calculate mixing 21 AD nc e 21 4 2 1 ROUTING and Use qm 21 4 2 2 Pressure tubing and nnne nennen nnn nnns 21 4 3 Economic use Of gases voit ett ds eia e ein e edet ta ute la 22 4 3 1 Output npe Er HM I 22 4 3 2 Backwards reduction of flows for 22 4 3 3 Quality of input 23 44 Wetting eee aede tiae ae ade dien 23 4 4 1 Wetting stage temperature and vapor pressure Of 23 4 5 Modesof Operation ix te ete etel ete
3. enenatis 13 3 2 1 2x ERR eue ea ME 13 3 2 2 DOCUMENTS Rr 13 3 2 3 Cabinet and front ea e ERN RR EORR 13 3 2 4 orici c E 13 3 2 5 Glass tubes eec eh D RE RI ds 13 3 2 6 Remove the side and rear panels 13 3 2 7 Wetting stage ice o eve e eee ee eee antra os 13 3 2 8 Bubbler liquidz suite eter 14 3 2 9 In case of visible sessi nnns 14 3 3 Learn how to operate the valves before you 14 3 4 Assembly uuo Roh EE GI EV CREE 14 3 4 1 Bubbler liquid filling rettet eet tte e 15 3 4 2 Bubbler maintenance 15 3 5 Wetting Stages ios e eerte 15 3 5 1 Water t uA A e n netten 15 3 5 2 Te mperatute ctio tec eiue etae te tete tete eue ense taut tae t d 15 4 3 5 3 Fill the Wetting stages e reete 15 3 5 3 1 Maintenance of the wetting stages 3 5 4 Extra and custom wetting 8 16 3 5 5 5 e EC 16 3 5 6 Connection of ventilation and overpressure 17 3 6 Connection of input 5 nasse ie ie 17 3 7 Connection of outlets to measurement cells
4. 31 C 32 C 33 C kPa 2 487 2 645 2 810 2 985 3 169 3 363 3 567 3 782 4 008 4 245 4 495 4 758 5 034 4 5 Modes of operation 4 5 1 One gas H O If you are simply going to supply one unmixed input gas as such wet dry or a mixture of wet and dry you may select that gas as GB and supply it to Mix4 using F7 and having Mix4S selector on GB setting pH O in Mix5 as needed with Mix5DS selected as Mix4 23 ProGasMix Manual 15 07 2013 In this mode the first parts of the mixer be separately used to supply other gases GA GI pH O and their mixtures through Mix3 for other purposes 4 5 2 Mixture of two gases H O The most commonly applied mixes of two gases are O in inert gas air in inert gas CO in CO and H in inert gas All these typically have the purpose of controlling pO If you are mixing two gases use GA as the one generally most dilute and as the diluent normally the inert gas or CO GA can then be used undiluted or diluted roughly to 1 65 and to 1 4257 by the two first flowmeter pairs It is however more economical to use smaller mixing rations and more flowmeter pairs To include one more flowmeter pair route the Mix2 to F7 selecting Mix2 on Mix4S selector and dilute further up to 1 132500 to make Mix4 Even higher ratios can be obtained by using a pre diluted input gas e g air as diluted O or 5 96 in Ar or by utilizing F9 and F10 4 5 3 Mixture of three gases H20 This mode
5. 4 6 3 Possible flowmeter issues essere 31 Suggestions for flowmeter settings for various uses sese 31 4 7 1 OUtDUts ren ret t ecu ne eth e hr 31 4 7 2 Small variations in partial pressure 32 4 7 3 Small differences between Mix3 and 5 32 4 7 4 Logarithmic variations in partial 32 4 8 Characteristics of Wetting lt 4 444 33 4 9 Back suction risks ice te a Te eet 33 4 10 Calculational principles 33 4 11 High temperature nnns 33 4 12 Normal operations 34 4 13 RSEN MINI 34 4 14 Typical extensions and 5 0000 34 Special procedures ET 34 5 1 Flushing of gas lines to preserve purity of 34 5 1 1 Flushing of connections during gas bottle replacement 34 5 1 2 Flushing of input gas line for connection of a new gas to a line 34 5 2 Procedures to optimize purity e g inertness or dryness of a gas in the mixer 34 53
6. 7 1 4 Materials Material Locations Notes Copper Copper is used in gas lines Brass All valves include brass All copper tube joint adapters have brass ferrules Stainless steel Wetting stages Polycarbonate plate Front panel Undefined painted metal Casing and frame Glass Bubblers Halocarbon 6 3 oil Bubblers Boiling Point Decomposes gt 200 Vapor Pressure lt 0 1 mm Hg 21 Specific Gravity 20 1 ca 1 9 38 Solubility in Water Negligible Natural rubber Bubbler caps Viton Buna N O rings Quick connects and needle valves Silicone hose Bubblers ventilation hoses Undefined plastic Ventilation hose joints ventilation hose caps Polyurethane tube Wetting stage refill lines Also silicon and PVC 7 1 5 Fired or otherwise heated pressure equipment To be entered 7 1 6 Piping To be entered 7 1 7 Specific quantitative requirements for certain pressure equipment To be entered 7 2 Reference to other directories The ProGasMix carries no voltages higher than 24 V DC or AC and thus has no hazards related to electricity The ProGasMix does not conform to the EC ATEX directory for equipment to be used in environments with flammable or explosive fluids 42 ProGasMix Manual 15 07 2013 8 GasMix software This is a short introduction to GasMix program Please see the full and individual GasMix manual pdf for a more complete and updated version 8 1 Introduction 8 1 1 What is GasMix The GasMix program is
7. F1 F2 F3 F4 Mix1 Mix2 Log Mix2 25 25 50 5 1 10 120 13 25 25 20 10 1 10 1 50 17 25 25 25 25 1 10 1 100 2 0 Same steps be done for Mix4 with Mix4S as Mix2 as in example below or with the stages F5 F6 and F9 F10 F1 F2 F3 F4 F7 F8 Mix1 Mix2 Mix4 Log Mix4 25 25 25 25 25 25 1 10 1 100 1200 23 25 25 25 25 20 55 1 10 1 100 1 500 2 7 25 25 25 25 10 58 1 10 1 100 1 1000 3 0 32 ProGasMix Manual 15 07 2013 We have now covered three orders of magnitude with three stages but each individual step can be pushed further for greater range for example Fl F2 F4 F7 F8 Mix1 Mix2 Mix4 Log Mix4 25 20 25 20 52 1 13 1 159 1 2000 3 3 27 45 27 45 50 1 17 1 295 1 5072 3 7 20 40 20 40 55 1 21 1 464 1 10000 4 20 55 20 55 65 1 31 1 930 1 25730 4 5 10 65 10 65 65 1 65 1 4225 1 116891 5 4 8 Characteristics of wetting stages Typically two identical wetting stages are located in the insulated and Peltier cooled container One is W1 and the other is W3 Label Name Notes Al C En A Incoming gas From Mix3Win or MixSWin B Distilled water Gas bubbling through the water C Outgoing gas To Mix3Wout or MixSWout D Transparent Transparent hose acts as water level indicator Loop hose downwards acts as water lock E Refil amp Cap W1Re or W3Re for safety in case water lock dries out D 4 9 Back suction risk When a large volume such as sample holder just volume from now on is connected to the mixer there is a r
8. e Special procedures and advanced information e Technical specifications NorECs AS July 2013 ProGasMix Manual 15 07 2013 2 Safety In this section we list important aspects of safety of using the ProGasMix Included are brief descriptions of normal operation assessments of the possible risks and finally recommended safety procedures 2 1 Normal use according to specifications The ProGasMix can connect to three gases and mix them in wide ranges of ratios into 2 mixtures and control the water vapor levels for both mixtures individually Input gas and input gas forms the output mixture 1 Input gas B and input gas forms the output mixture 2 2 2 Riskassessment The mixer itself is passive and poses no threat of toxic electrical or mechanical kind The gases connected to the mixer are selected by the user and this forms the main risk misuse and human error This manual defines the safe use but the mixer itself is stupid it offers no identification of or regulation according to gas species the mixer physically treats any gas exactly the same way even if dangerous or non permitted gases were connected to it The gases used the mixing action and the ventilation of excess gases are all decided selected and operated purely by the user so the possibility of a misuse is the main risk to prepare for The mixer is designed to minimize these risks and possible consequences Secondary risks consist of possible malfunction s
9. now being wetted in the wetting stage F6 will select the amount and type of gas that forms the dry part of Mix3 elected with Mix3DS between 2 and Gl To make Mix 5 select a source for F7 using Mix4S and select GB Turn up flowmeter F7 and F8 to a small flow e g 30 mm Repeat the Mix3 steps but for F9 F10 MixSWin MixSWout to form Mix5 There should by now run some gas in all of the 10 first flowmeters and all pressure control columns should be bubbling 3 9 5 Leakage test When all pressure control columns have been bubbling for a few minutes it is time to do the overall leakage test Starting from the last flowmeters with biggest number close all flowmeters For each pair the supply of gas stops and no gas is consumed Thus the pressure control column should remain at the bottom of the bubbling tube A gas tight system keeps the columns at the bottom position for at least 10 minutes Any tendency that the columns raise indicates leakage Identify the leakage e g by using Snoop repair if possible and try the test again Note This test of the gas tightness of the ProGasMix is sufficient for its normal and safe operation It can be classified as low vacuum gas tight It is not and is not intended to be high vacuum gas tight Note Do not at this stage attempt to test gas tightness using a vacuum pump the vacuum will give violent back suction in the bubbling stages with danger of contaminating tubing and flowmeter
10. outlets without their caps on This is the case when ventilation is arranged by a hose leading out but with no ventilation machinery to actively move the gas out Each wetting stage has 4 markings on the refill tube for example for WI the refilling tube has markings Min1 Min2 1 2 1 is for refilling when the system has open outlet like in the previous chapter Marks 2 are for refilling when the system is pressurized and in operation 3 5 4 Extra and custom wetting stages By default W2 and W4 are bypasses at delivery of the ProGasMix Wetting stages W2 and W4 may however be equipped with e g D O containing stages or other custom stages One may also consider to use these for wetting stages that give much less H20 contents than pure water so that a larger range of mixing wet and dry can be reached by combining the two wetting stages For instance a solid state mixture of a hydrate and an anhydrate may be considered One may also simply use W2 and W4 as extra wetting stages for just to increase the capacity Such installations at the user s site are the user installer s responsibility NorECs may provide assistance and advice One may note that the installation does not have to be safe against high pressures the wetting stages are not exposed to high pressures 3 5 5 Drying stages By default the ProGasMix is not equipped with drying stages and the input gases are assumed dry enough The construction however all
11. 96 H20 at 15 C with maximum dilution This level of water does not influence much on the partial pressure of the other gases in the mixture from dry to fully wet they decrease by 3 96 relatively For instance pO in dry pure is 1 atm while pO in wet is 0 97 atm Such variations in with nearly constant is essential e g for studies of proton conductors under oxidizing conditions Similarly the pH O can be changed in CO CO buffer mixtures 24 ProGasMix Manual 15 07 2013 without affecting pO much But for H based reducing atmospheres pH O directly affects pO and another mode and approach is used see next section The maximum pH O depends of the wetting stage temperature 4 5 5 Changing the water content pH O and that of another active component e g pH at the same ratio Assume the mixture going through a wetting stage is H in inert gas e g Ar from a premix and or from mixing in the first two or three stages Now we switch Mix3DS to GI Then the drying stage bypass is not carrying the same mixture as the wetting stage but instead dry GI Ar In the wetting stage we get wet gt i e gt 2 When this is mixed with the dry Ar we are decreasing both the H20 and the H2 contents but their ratio remains constant At high temperature equilibrium this means that we are changing pH and while pO remains constant This is essential for investigations of proton conductor
12. Manual 15 07 2013 4 12 Normal operations maintenance Enter here 4 13 Service procedures Enter here 4 14 Typical extensions and modifications Enter here 5 Special procedures 5 1 Flushing of gas lines to preserve purity of gases 5 1 1 Flushing of connections during gas bottle replacement To be entered 5 1 2 Flushing of input gas line for connection of a new gas to a line When replacing an input gas with another gas one must consider that there is leftover of the previous gas in the system Some of the previous gas has higher pressure also the short copper tube from the quick connect to the pressure regulator has the previous gas with the pressure that the feed line had Past the pressure regulator the previously used gas has very low pressure and it may exist in the mixer as diluted or pure If the new gas is not safe to be used with the old gas the mixer needs to be flushed with inert gas This is done in following steps 1 Stop all other use of the mixer 2 Flush the volume between the quick connect and the pressure regulator by connecting an inert gas to the gas line to be flushed This procedure will also flush bubblers B1 or B4 e Ifthe gas line is input gas A open F1 for a large flow for few minutes close F1 and disconnect the flush gas e Ifthe gas line is input gas set Mix4S to input gas B open F7 for a large flow for few minutes close F7 and disconnect the flush gas 3 To flush the rest of the mixer ha
13. ProGasMix comprises pressurized accessories and tubing of a total volume less than 1 L The ProGasMix comprises pressurized tubing of DN 6 On this bases referring to Annex Tables 1 7 the ProGasMix falls below Category of the PED It is thus not CE classified but manufactured according to Sound Engineering Practices SEP Nevertheless it is instructive to treat the pressure related safety aspects of the ProGasMix according to the PED notably Annex 7 1 2 Design 7 1 2 1 General The main design and component selection of the ProGasMix was made in the 1980s and is published in scientific literature It has since been built in a number of units with minor changes and improvements The main change is the replacement of wetting stages first using saturated solutions of NH4 SO for dew point suppression into stages using saturated solutions of KBr for lower vapor pressure of the salt and finally into the present use of Peltier stage cooling instead of salt solutions Furthermore the drying stage has been changed from being P205 based to being based on a commercial mol sieve stage and eventually skipped Both the wetting and drying stages now are made of steel instead of glass eliminating risk of breakage and damage from broken glass The design and the many units built and continuously used over more than 20 years makes the ProGasMix well proven in terms of functionality lifetime and safety 7 1 2 2 Design for adequate
14. S mall flows 0 16 1 6 In h MO80E01G Metallic F2 6 10 L arge flows 0 69 10 7 In h K080H03G Metallic F7 F8 11 12 M edium flows 0 16 5 0 In h MO080H01G The tubes are equipped with a scale The reading on the scale is in mm and is called float travel FT The scale is 0 65 mm Flowmeters cannot detect very small flows so there is a region of unknown flow between the 0 mm mark and the lowest possible location for the float When the float is at the bottom of the tube and the needle valve is fully closed the flow is considered to be zero and in the program such condition is designated with FT 0 On the flowmeter scale 0 mm is however already a significant flow Due this contradiction the lowest usable flow is 1 mm FT On the high end the ball can pass beyond the top reading of FT 65 mm but is eventually stopped at a metallic stopper The flow can thus be much higher than the maximum reading but it won t be readable Such high flows are usable for example for flushing the mixer The flow required to keep a ball floating at a certain height is dependent of the viscosity and density of the gas or gas mixture Thus as extremes a certain FT with H or He as the gas represents a much higher flow than of CO or Ar The flow ranges in specifications and general calculations are given in air and these ranges and ratios are naturally depending on what gases are being used Flowmeter readings in FT mm must be converted int
15. for wetting stage cooling operates with one of the two following modes Target temperature mode PR1 Program 1 PR1 tries to cool down the interior of the wetting stage box to a fixed temperature set in the controller We recommend using the Target temperature mode at 12 which is preprogrammed into the controller Preprogrammed mode definitions Mode PR 1 Heating 0 0 Heating hysteresis HY 0 5 Cooling C 18 0 Cooling hysteresis HY 0 5 Safety Shutdown CH2 60 Fan follow up time LUFt 1 This program tries to cool and maintain 18 with 0 5 hysteresis to save mechanical part lifetime Power is cut off if Peltier heats above 60 C which may be the case if the fans are damaged or the back door to the cooling box is open Fans will run for 1 minute after the Peltier element power is cut off to dissipate the remaining heat on the hot side of the heat sink 35 ProGasMix Manual 15 07 2013 For more details about programming the temperature controller refer to Temperature controller for Peltier module document by the manufacturer of the temperature controller unit provided with ProGasMix 6 Technical specifications and reference 6 1 ProGasMix flow sheet 36 VentA WiRe O Gas to be diluted Quick connect with valve Safety regulation 2a Dilutant inert gas Quick connect with valve Safety regulation 1 Mix3Win Input Gas Gas to be diluted Quick connect Mix2 with valve Saf
16. in place and intact and that the tube and bulk part look intact If OK reassemble and tighten lightly using proper re tightening procedure not the one for new ferrules If no leak is spotted contact NorECs for further advice 3 9 7 Leavethe mixer with overpressure When not in use you may well leave the whole or parts of the mixer with overpressure especially if filled with an inert gas You may even want to leave a tiny flow of inert gas going to be sure to keep it filled and ready If there is no flow be sure to close both ends of the wetting stages to prevent water vapour to back diffuse into the system 4 Normal operation 4 1 Use of software to calculate mixing result In the following we will go through the use of the mixer As we move on the reader may feel overwhelmed by all the factors that affect the mixing and the complexity of obtaining the final composition of the output gas mixtures Let us therefore rush in and say that these calculations are done by a computer program Since the mixer is manually operated and with manually set flows it is important to understand it but the computer and software will do all the hard work after the flowmeter readings are entered The software we provide with ProGasMix is described in a later section 4 2 Output gas 4 2 1 Routing and use Once you have established Mix3 and or Mix5 either of the output lines O1 O2 may be directed to be fed from Mix3 or Mix5 via the output selection valv
17. nnne nnns 40 7 1 2 3 Provisions to ensure safe handling and 40 7 1 2 4 Means 4 11 0 0 00 nennen 41 7 1 2 5 Means of draining and 41 7 1 2 6 Corrosion or other chemical attack 41 1 27 VIC ERES 41 7 1 2 8 Assemblies 41 7 1 2 9 Provisions for filling and 41 7 1 2 10 Protection against exceeding the allowable limits of pressure equipment 41 7 1 2 11 Safety accessories eee abe e ir gts to e Oa Run 41 7 1 2 12 External Ge aar nae 41 7 1 3 Manufacturing ttt titer dut e titus 41 7 1 4 Materials sept e te s obe eee 42 7 1 5 Fired or otherwise heated pressure 42 7 1 6 PIPING dee 42 7 1 7 Specific quantitative requirements for certain pressure equipment 42 7 2 Reference to other 42 8 GaSMIX SoftWare T 43 8 1 dnitrodU ctiOD d eec cere RP e I RR ge FO 43 8 1 1 Whatis GasMIX9 siete 43 8 12 5 seen ENT Te 43 8 1 3 Note GasMix emulates but does not control your 43 8 2 quick star
18. of operation is not possible with a standard ProGasMix FC The FC in the name stands for Fuel Cell and for safety reasons it was made impossible to mix three gases in the mixer This text was left here for the curiosity of the user If such use is of interest it is possible to use pre mixed gases or have the mixer modified Mixes of three different gases may comprise mixing CO and CO and then adding Ar for control of the carbon activity ac This may in turn be because you are interested in the effects of the activity of carbon e g at constant pO or because you want to reduce the degree of carbon precipitation via 2CO g CO2 g C s which is driven to the left by reduced total content of CO CO Another use of a third gas might be to mix e g N and Ar and then mixing in O Variations in the first stages may then change to study effects of nitrogen activity at relatively constant may be replaced by to study effects of carbonatisation may also be replaced by e g He When He replaces Ar in a mixture effects of gas phase diffusion on kinetics change and may be studied 4 5 4 Changing the water content pH O in a mixture The water content of Mix3 can be varied down from wet ca H20 at 25 C by using F5 to dry by having Mix3DS at Mix2 and using F8 similarly for Mix5 In addition the wet can be mixed with dry to cover three orders of magnitude of water content from 3 96 down to 0 05 ca 1 7
19. row of vertical rectangles representing the Flowmeters Some of the Flowmeters may be fed from the Input gases and this is then illustrated by colored connecting lines one color for each Input gas Above the flowmeters gas lines show how the flowmeters are connected to form Mixtures Each Mixture has a color and there is one small boxes attached to the Mixture line above the first flowmeter connected to that Mixture Additional small boxes directly below or above a flowmeter represent stages for fixing the partial pressure of some component normally H O wetting or drying stages On the top you find rectangles representing your measurement or reaction chambers here called Output cells for which temperature and total pressure can be set so as to allow calculation of equilibrium partial pressures 43 ProGasMix Manual 15 07 2013 The right hand side of the window is reserved for tables in use during editing and data entry Moreover results of mixing and equilibrium calculations will appear on the top of the window During editing of calibration curves also parts of the mixer schematic temporarily becomes covered with tables and graphs 44
20. tr st t ient 23 4 5 1 One gast H50 xit b Bde n iden 23 4 5 2 Mixture of two gases 20 24 4 5 3 Mixture of three gases 20 nennen enhn nnn 24 4 5 4 Changing the water content pH O in a 24 4 5 5 Changing the water content pH O and that of another active component lee at the Sammie ratios uneven de 25 4 5 6 Large gradients fuel cell and permeation tests 25 4 5 6 22 sF el cells oie rene Ed tee Oe cae o 4 5 6 2 Gas permeation teet ote mti ce e ox dee eden 4 5 7 Small gradients for transport number lt 26 4 5 7 1 General principles ierat deter e eh 4 5 7 2 Background offset voltage minimization and elimination 4 5 7 3 Oxygen activity 4 5 7 4 Hydrogen activity 4 5 7 5 Other activity gradients cesses eene nennen 4 5 8 e eve Lob eee 27 4 5 9 H D isotope effects aedi tertie td territi e 27 Characteristics of the flowmeters eese nennen nnns 27 4 6 1 Additional details on absolute flows eee 28 4 6 2 Flowmeter mixing ratios general overview 2 30
21. 1 ProGasMix front panel markings and functions Marking Function GA Input Gas A GI Input Gas Inert GB Input Gas B F1 F12 Flowmeter 1 12 Mix3DS Mixture 3 Dry Source Mix5DS Mixture 5 Dry Source 45 Mixture 4 Source Mix3Win Mixture 3 Wet in Mix3Wout Mixture 3 Wet out Mix5Win Mixture 5 Wet in MixSWout Mixture 5 Wet out Notes Swagelok 1 8 inch quick connects with shutoff valve Safety regulations 1 and 2a Flowmeters with needle valve F2 F4 F6 F8 and F10 have higher flow range than the rest Left Mix2 Right Gl Up Closed Left Mix4 Right Up Closed Left Mix2 Top Right GB Up GI Safety regulation 2b Left W1 Right W2 Up Closed Left W1 Right W2 Up Closed Left W3 Right W4 Up Closed Left W3 Right W4 Up Closed 6 2 2 ProGasMix exterior markings and functions Marking Function Notes Vent A Ventilation A for GA and GI Safety regulation 3 Vent B Ventilation B for GB and GI Safety regulation 3 W1Re and Wetting stage 1 and 3 Refill access Use distilled or de ionized water only Do not W3Re overfill 24VDC 24VDC supply for Peltier element and Round entry in the back panel lights 6 2 3 The ProGasMix interior markings and functions Marking Function Notes PR Pressure Regulator Pre set to suitable pressure 1 2bar a B1 B5 Bubblers 1 to 5 Glass tube bubbler system with bubbler liquid for respective mixes W1 and Wetting stages 1 and 3 Temperature controlled st
22. ProGasMIx FC E ome init n P NN 2 Cx al Mix Jou t MixgWin DIPL wr Tz V ws User Manual NorECs AS List of contents 1 PH 8 2 9 2 1 Normal use according to 9 2 2 Riskassessment ets rene ee rra E Eee Men 9 2 2 1 Mis se hazatds ERR e ER 10 2 2 2 Safety regulatiOriSs tec ede 10 2 2 2 1 Additional information on safety regulation 20 23 Safetyrecommendations eise i te edes saccade tid ese ce ERE 11 2 4 Non hazardous aspects and built in safety 11 2 5 Additional safety considerations esses eene ennt nnn nnns 11 2 6 Equipment classification 000 0 0 eene 12 2 7 Responsibility rr em eet err e ke e ba ee ure ERN Re 12 3 Installatiotiz tae RR VIR ER FIN ITE 13 3 1 Before unpacking Read this 2 22 13 3 1 1 Initial valve positions nennen nnns 13 3 1 2 Initial pressure regulator 13 3 1 3 Transport indiCator i cR iet 13 3 2 Unpacking and lt 5
23. ards order of the mixtures the flows of gases to the minimum while still satisfying e mixing ratio e use of acceptable ranges of the flowmeters e bubbling in all stages to ensure stable pressures and flows 22 ProGasMix Manual 15 07 2013 Thus the experienced ProGasMix user often starts from Mix1 supplying ample amounts of gas so as to quickly and stably obtain bubbling and constant pressures and flows and then when the output flows are set backwards down regulating for minimum flows In this way pure unmixed gases or mixtures not involving very large ratios can be made very economically For somewhat higher ratios using two or three stages Mix1 Mix2 and or Mix3 with small flows can in fact be more economic than one stage with one high flow Nevertheless one cannot escape from a large consumption of gas when very large ratios are attained then necessarily a lot of the main diluting gas is running in two or three or four stages 4 3 3 Quality of input gases Here just a word on the need for purity of input gases High temperature cells usually cannot maintain oxygen levels much below 10 ppm and not water levels below 30 ppm Thus the purity of the gases especially the inert ones that are often used for dilution and in large quantities need probably not be better than 99 999 96 In many cases the main impurities are in any case another inert gas with no or minimal consequences so that even lower puritie
24. at bubbler liquid columns are out of normal state or that there is too much water in a wetting stage Slow sliding changes in the float travel are normally due to the valve of the flowmeter relaxing a little in its rubber O ring seals and against its needle orifice This is normal It is for this reason not always easy to set the flowmeters to certain flows in one try Instead one typically set them to flows approximately at the desired flow and then leaves the valve to relax for some minutes and fine tunes the flows Other behaviors of unstable float travel may have other less normal flow Irregular jumps indicate that there is liquid somewhere in the gas line hopefully just condensed water Check also that the wetting stage is not empty and thus leaking out If you discover that a float is stuck and then check whether you may have opened the flow too much and that gas is flooding the bubblers then turn it down before you proceed NOTE It only takes a dust particle to get the ball stuck especially near the bottom It usually loosens by knocking gently at the front polycarbonate or the top of the flowmeter Even if you can take the tube out for cleaning it is actually difficult to do that procedure without entering more dust particles than you remove so we recommend that you refrain from taking them out unless you have a remaining recurring problem If there is a chance that it is stuck because of condensed water it is best to just le
25. bes Your ProGasMix is delivered with a number of glass tubes 3 cm in diameter and about 50 cm long They are mounted upright in the ProGasMix or packed separately Check that they look undamaged from transport 3 2 6 Remove the side and rear panels Use appropriate screwdriver s to loosen necessary screws and remove the two side panels and the rear panel Do not attempt to loosen the front plate 3 2 7 Wetting stage box An insulating box containing the wetting stage s is located at the bottom back part of the mixer Remove the back side of the foam box and retrieve the items stored there Inspect any wetting stage construction for damage 13 ProGasMix Manual 15 07 2013 3 2 8 Bubbler liquid ProGasMix is shipped with Halocarbon 6 3 which is inert and harmless It will be used for filling the bubblers to pre set levels described later in the manual Container of a liquid is packed inside ProGasMix separately and filled in the appropriate places in the ProGasMix during installation Find out where the container is extract it and set it aside 3 2 9 case of visible damage In case of visible damage of any of the items listed above or any other item it is likely that this has resulted from rough handling during transport Please notify NorECs and if possible and without delay the transporter 3 3 Learn how to operate the valves before you begin At this stage before we have connected anything or filled any liquids and as you
26. d the pressure regulator are extremely small few cubic centimeters well below the lower limit of the regulations The mixer uses an external adaptor to lower the voltages used to 24V DC The documentation for the adapter is shipped with the mixer On the mixer itself the voltage used is 24V DC which does not pose any electric hazard or require any certifications Further information about the mixer can be found in chapter Material and Safety reference 2 7 Statement of responsibility The persons signed below agree and understand that The manufacturer NorECs Norwegian Electro Ceramics AS has provided sufficient information for safe and proper use of the mixer The manufacturer NorECs has provided sufficient information on the possible risks and how to avoid them and prepare for them in case of misuse e The safety of operation of the mixer depends solely of the user s choices and actions e That NorECs cannot be held responsible for any consequences of any use of the mixer Name date and organization Name date and organization Signature Signature Name date and organization Name date and organization Signature Signature Name date and organization Name date and organization Signature Signature 12 ProGasMix Manual 15 07 2013 3 Installation Installation means sequentially doing all steps of this section 3 1 Before unpacking Read this first Before you unpack the ProGasMix there are a few instruct
27. d mixtures involved The ProGasMix starts with 3 input gases GA GI and GB These are supplied at a pressure of normally a few bars atm but the mixer has internal pre set pressure regulator reducing the pressures even further gas GA is mixed with gas Gl in several steps using pairs of flowmeters F1 with gas GA and F2 with gas GI form a mixture 1 Mix1 The Mix1 is mixed with more gas with flowmeters and F4 to form Mix2 The Mix4 is made same way but using gas GB or Mix2 for F7 and gas GI for F8 Mix2 and Mix4 form the bases of the two final mixtures Mix3 and Mix5 but first they will go through individual stages to control their water vapor levels Mix2 is split in two portions one to be wetted and one to remain dry and these two portions are mixed by flowmeter pair F5 F6 into Mix3 Similarly Mix4 is split in two portions wetted or not and these two portions are mixed by flowmeter pair F9 F10 into Mix5 Each mixture Mix3 or Mix5 is a controlled composition including water vapor level It is typically used for varying oxygen activity over a large range while keeping the water vapor level constant or vice versa Each wetting stage has two pathways W1 W2 for Mix3 and W3 and W4 for Mix5 Normally is used for the wetting W1 and W3 while one is used as a bypass W2 and W4 However other uses such as D O wetting etc are possible For each flowmeter pair and mixture Mix1 Mix5 a pressure column bubb
28. e OS Typically a measurement cell like a NorECs ProboStat is connected with its two chambers being fed from O1 or O2 with the gas stream split after the mixer Transients or reversing of gas composition gradients can be accomplished by simply switching the position of OS 4 2 2 Pressure tubing and flow 21 ProGasMix Manual 15 07 2013 The final stages Mix3 and Mix5 of the ProGasMix have around 0 019 bar overpressure corresponding to the 10 cm liquid overpressure control columns B3 and B5 and density of 1 9 of Halocarbon oil 6 3 This may limit the flow that can be supplied to the outputs if the tubing out of the ProGasMix is too thin and long Consider adjusting bubbler liquid heights or using more than 1 8 tubing in this case e g 3 16 or 1 4 via converting unions Do not use plastic or rubber hose tubing if inertness or dryness of the gas is essential O and especially H O in diffuse quickly through most hose materials Normally some tubing after the cell or furnace chamber is used to vent the off gases This also serves the purpose of preventing back diffusion of unwanted components from air if inertness and or dryness is important but may again limit flow Bubbling the outlets of the cell or furnace chamber through a cm or two of liquid such as water gives a nice visual confirmation of flows and a small overpressure that further prevents back diffusion in the tubing and in diffusion through a leaky cell Use of oil preve
29. e g with MS or GC of the gas composition after the membrane passage on the feed or in particular permeate side may be used to obtain the permeation of species in the gases For measurements of oxygen permeation one may for instance supply O N mixtures as feed gas one side On the permeate side using Ar one may analyse the content of and If the membrane is permeable only to oxygen e g through ambipolar diffusion of oxide ions and electrons the content of may be taken to reflect leakage through pores cracks or poor seals and after correcting for this using the fractions of and O in the feed gas and assuming macroscopic flow in the leaks one may obtain the real permeation of oxygen through the membrane material 25 ProGasMix Manual 15 07 2013 If the membrane is at high temperature a dilute H Ar mixture may be used instead giving a much higher chemical driving force for oxygen which flux is now measured via the H O content in the permeate gas In a similar manner a mix of H and an inert gas can be supplied as feed gas The permeate is then typically another inert gas and the levels of H and the feed inert gas are measured Wetting the feed gas is probably a good choice Wetting the permeate side may give the side effect that any transport of oxygen from the permeate side to the feed side may split water and leave hydrogen which is then incorrectly assigned to permeation of hydrogen 4 5 7 Small grad
30. e pairs of M giving accurate medium flows and ratios from 1 30 to 30 1 With following float travels one can get the general idea of the possible mixing ratios available S float travel mm Lfloattravel mm L S ratio 60 10 1 25 25 10 15 30 20 20 55 30 10 65 65 Also for S the ratio between flows at 10 mm and at 65 mm is always 1 10 and between those flows not too far off from linear dependency between those two points With same float travels for S and L the ratio of flows is 10 at 25mm and goes down both on higher and smaller flows S float travel mm float travel mm L S ratio 15 15 8 74 25 25 9 83 35 35 8 99 45 45 7 88 55 55 7 13 65 65 6 56 30 ProGasMix Manual 15 07 2013 The remaining float meter pairs 7 amp 8 and F11 amp F12 are both M type and have the following characteristics M float travel mm float travel mm L S ratio 1 65 27 7 35 35 1 65 1 0 036 4 6 3 Possible flowmeter issues Unstable float travel has normally two reasons Small fluctuations at a regular rate are normal and are due to the tiny variations in pressure arising from the forming and then released bubbles If the float is fluctuating the float travel reading is then taken at an average of the high and low positions If these fluctuations get unusually large it indicates that the available pressure difference working as the driving force is getting small and thus more subject to the variations from bubbles This may indicate th
31. e pressure of Mix1 constant regardless of flows Test this change one of the flows F1 or F2 and see how it does mainly not affect the other flowmeter as long as B1 bubbles When B1 bubbles you can use Mix1 to feed flowmeter F3 Turn it up to say 30 mm You can use as much flow as you want but not more than F1 and F2 supply that is only as much as B1 keeps bubbling If B1 stops bubbling you are losing the constant pressures situation and the mixtures made cannot be precisely calculated NOTE This is a good time to make sure you understand that the gas that bubbles in the overpressure bubblers like now B1 is not used for making the final mixtures What bubbles is the excess gas that we don t need While bubbling is essential for maintaining constant pressure conditions and for getting rid of 19 ProGasMix Manual 15 07 2013 excess gas it is of course also important to reduce unnecessary bubbling to a minimum to reduce gas consumption Now you can mix in more gas into Mix2 by turning up flowmeter F4 to say 30 mm This is fed from gas similarly as flowmeter F2 Now we will run Mix2 through wetting stage and dry line and mix the portions into Mix3 which is a final output mixture and which bubbles in B3 Open the inlet Mix3Win and outlet Mix3Wout for wetting stage WI for gas coming from Mix2 and going into Mix3 by pointing both valves to WI Turn up flowmeter F5 till a small flow e g 30 mm This flow is
32. eel bubblers w3 PELTIER Peltier element Peltier element for wetting stage cooling TC Temperature Temperature controller and indicator Control indicator 38 ProGasMix Manual 15 07 2013 6 3 Other reference lists 6 3 1 Shipment contents Item ProGasMix 8 x Quick connect stem Part number B QM2 D 200 6 3 2 Included documents Item Power supply CE declaration Halocarbon 6 3 material safety sheet Halocarbon 6 3 properties page EC Declaration of Conformity Risk assessment Flowchart Peltier manual GasMix manual Location On a pallet Inside wetting stage Description Function To connect the mixer inputs and outputs to gas 1 8 inch copper tube gas lines Amount Specifications and conformity for the external power supply used 1 with ProGasMix Material safety data sheet for Halocarbon 4 2 6 3 27 56 95 1 200 400 700 1000N oils Density and viscosity data PGM conformity with applicable directives Extract from this manual printed separately Flowchart of the mixer Peltier controller operation manual GasMix software manual 39 ProGasMix Manual 15 07 2013 7 Material and safety reference 7 1 Reference to the EC Pressure Equipment Directory PED 7 1 1 Conformity Compliance and General issues The ProGasMix may be used with fluids gases in Group 1 Dangerous and Group 2 Other The ProGasMix may receive and handle gases at pressures up to 15 bar a The
33. ety regulation 2a Pressure regulator Preset to roughly 1 2 bar input pressure 15 bar a Small flow flowmeter 0 5 26 air Large flow flowmeter 18 208 min min air Medium flow flowmeter 3 83 min min ar F3 Vent A Ventilation A A vents are connected to each other Safety regulation 3 Ventilation B B vents are connected to each other Safety regulation 3 Bubbler 1 to 5 Bubblers for constant pressure i i i i Mixture 3 Dry Source 2 way selector between Mix2 and M 2 i i w2 277777777070 Mixture 3 Wet out 2 way selector between W1 and w2 Wetting stage 1 and 3 Peltier cooled wetting stages Vent A Vent A Vent A Vent B Wire and Wetting stage 1 and 3 Refill entry with cap W3re refill Wetting stage 2 and 4 Bypass placeholder for alternate wetting stage 45 Mixture 4 Source 4 way selector between Mix2 and GB Safety regulation 2b Mixture 5 Dry Source 2 way selector between Mix4 and GI 5 wei vien Waara Mixture 5 Wet out IEEE WA Output selector Connect Mix3 and Mix5 to F11 and F12 with possibility to inverse the order Output 1 and Output 2 Oland 02 Quick connect with valve ProGasMix Manual 15 07 2013 h 40 cm B2 30 cm B3 h 10 cm B4 h 20 cm B5 10 cm ProGasMix Manual 15 07 2013 6 2 ProGasMix marking and definitions 6 2
34. go through the points below feel free to try the action of the different types of valves so that you are familiar with them and how they work However be sure to set each back to the original position e ProGasMix has three types of valves The needle valves on all flowmeters the 2 way selection valves and the 4 way selection valve Donotuse excessive force any valve e Aneedle valve on each flowmeter is a fine metering valve It opens when turned counter clockwise It is not a stop valve and must not be forced hard into full stop Use a gentle force with two fingers this will sufficiently stop the gas flow for our purpose The valve knob turns fifteen full rotations A2 way valve can select between two open positions to connect to a third common connect It is closed in one middle position and can well be left in that position It cannot be moved past the other two positions sometimes called 3 way valve e A4 way valve can select between four open positions to connect to a fifth common connect It snaps to each four open positions sometimes called 5 way valve e In addition the mixer hosts quick connects Bulkhead part of the quick connect is mounted on the front panel and the stem part is or will be mounted on a 1 8 inch copper tube gas line to supply or to lead away the gas to or from the mixer Both the bulkhead and the stem part are equipped with a valve that is open when the two parts are connec
35. hen re plug the caps 3 4 2 Bubbler maintenance The bubbler liquid needs no maintenance By normal use it lasts infinitely A slight discoloration may occur especially getting yellowish to light brown if you are using carbon monoxide CO but that is normal and has no consequence and should not lead to replacement 3 5 Wetting stages Wetting stages bubble the used gas through temperature controlled water setting a known water vapor pressure W1 and W3 are working wetting stages W2 and W4 are bypasses when wetting is not required W2 and W4 also act as placeholders for custom wetting stages added by advanced users The transparent refill hose makes a downward loop from the wetting stage acting as water lock water level indicator and refill hose The refill hose is also connected to the ventilation outlet W1Re to VentA and W3Re to VentB to improve the mixer safety in case of complete wetting stage dry off and forgotten cap on wetting stage refill 3 5 1 Water For the wetting stages use distilled or ion exchanged water The water filled should not be above room temperature rather below when you fill it Refilling will alter the temperature of the wetting stage and affect the partial pressure of water a thing to keep in mind if refilling during operation 3 5 2 Temperature The temperature control unit TC for wetting stage cooling is preprogrammed to reach and hold a target temperature of 18 C This is a safe value definitel
36. iddle of the ball The accuracy of the flowmeters is not such that this actually matters but it is wise to stay with one way of doing it for the best possible reproducibility and accuracy of relative changes However there are considerable deviations from tube to tube and float to float There are also deviations from the curve shape within each tube Thus in principle each reading should use its own calibration curve for that tube and that float and that gas composition and those conditions T P This is hardly possible especially for the versatile ProGasMix and one must instead find and use a practical compromise This includes in the simplest case the use of one standard master curve for each float type and just applying different sizing factors for the various gas species The next level includes the use of several master curves for different types of gas Alternatively or additionally one may calibrate individual flowmeter ball pairs Experience has shown that the latter give hardly any improvement in investigations of properties over many orders of magnitude in partial pressure of a gas e g in the slope of log electrical conductivity vs log oxygen partial pressure We denote our tubes with small flow S and large flow L and tube with medium flow M Flowmeter pairs F1 amp F2 F3 amp F4 F5 amp F6 and F9 amp F10 are combinations of S and L and allow ratios from 1 1 to 1 65 for dilution Flowmeter pairs 7 amp 8 and F11 amp F12 ar
37. ients for transport number measurements 4 5 7 1 General principles By establishing a difference in chemical potential over a sample a driving force for mobile species affected is set up If the species s is charged a voltage or electromotive force EMF arises that is proportional to the transport number t of the species defined as t This emf is measured at open circuit by using high impedance voltmeters multimeters or electrometers and is thus often also referred to as an open circuit voltage OCV The method we are to describe therefore are called measurements of transport numbers by the OCV of concentration cells or simply the EMF method In its simplest form the voltage over the cell is derived from so called Wagner transport theory The partial current of each charge carrier involved is expressed in terms of the driving force gradient in electrochemical potential it experiences its conductivity and charge Then all partial currents are summed to a total current the expression equaled to zero in the OCV case and solved with respect to the electrical potential gradient This is integrated from side I to side to obtain the voltage over the sample 77 np 7 where U is the voltage between electrodes Il and t is the transport number of ion n with charge 2 and where p is the chemical potential of the corresponding neutral atomic species The expression thus sums up over all ionic species n fo
38. ions we want you to have read in beforehand 3 1 1 Initial valve positions During unpacking and initial installation of ProGasMix do NOT turn any of its valves This ensures that preinstalled drying stages remain closed and are not unnecessarily exposed to ambient humidity 3 1 2 Initial pressure regulator positions During unpacking and initial installation of ProGasMix do NOT alter the valve positions of the pressure regulators They are set to suitable pressure levels during manufacturing of the mixer 3 1 3 Transport indicator The ProGasMix package may be equipped with an external indicator that is ruptured if the package has been handled too roughly during transport Please check for it and notify NorECs and the transporter without delay if there is such an indicator and it is broken 3 2 Unpacking and inspection 3 2 1 Unpack Remove any outer packaging until the ProGasMix stands free on its four legs Please note that the center of mass is relatively high so use extra care removing the mixer from the pallet 3 2 2 Documents An envelope is located at the roof of ProGasMix containing set of documents for the mixer 3 2 3 Cabinet and front plate Inspect the cabinet for signs of damage from transport In particular inspect the front polycarbonate plate for cracks 3 2 4 Flowmeters Likewise identify the flowmeters on the front plate and check that the glass tube inside each flowmeter is standing upright and looks OK 3 2 5 Glass tu
39. isk of under pressure or back suction in certain conditions If and when such volume is at high temperature and then cooled back to room temperature it will have low pressure inside and gas will try to flow into it Normally this is not a problem since the volume outlets are open and will allow the pressure to equalize However if the volume outlets are closed plugged fitted with relief valve etc and the gas mixer is connected to the volume inlets and the gas supply is interrupted the user has decided to save gas or gas ran out and the mixer is not disconnected from the cell inlets the under pressure developing inside the volume will suck on the mixer itself Depending on the valve positions this may or may not be a problem If any of the wetting stages are connected to the outlet of the mixer the replacement air will be sucked though the refill tube of the wetting stage to no consequence If however none of the wetting stages are connected to the mixer outlet the under pressure will try to suck up the bubbler liquid The liquid is heavy and needs to be pulled up at least 20cm but after that it will be in the gas tubes and possibly enter into the flowmeters This will render the mixer useless until a throughout cleaning of the system is performed Such cleaning is a major undertaking that will take at least two days 4 10 Calculational principles of mixtures Enter here 4 11 High temperature equilibria Enter here 33 ProGasMix
40. isplay or from a computer connected to the mfm through USB cable The flow is controlled with the needle valve of the flowmeter and once the float has settled at a specific float travel the actual gas flow is recorded to the calibration table Once the table is ready with readings for each 5mm float travel it is transferred to the GasMix software Calibration curves used in the software must share equal conditions of testing with other calibration data used namely pressure in the flowmeter gas temperature and the unit of measured flow Once the data is obtained adding the information to the GasMix software is straightforward and is covered in the manual of the software 5 5 Bubbler refill In some cases a bubbler tube B1 B5 may need refilling Measure from the bottom of the tube and mark the height of your desired refill The refilling is easy but removing excess liquid is more complicated so be careful with the amounts Also be aware of what liquid your gas mixer has and use the same liquid You need a long nosed funnel max 8 mm nose outer diameter and a light weight bottle or a jug Do not try to pour from a heavy 2 5 L glass bottle or similar instead have a small amount of liquid in a small jug or a plastic bottle so that it will be easy to pour small amounts to the funnel without spillage Locate the tubes coming out of the metal cap on the chosen bubbler 5 6 Temperature controller programming The temperature control unit TC
41. ituations ProGasMix Manual 15 07 2013 2 2 1 1 2 3 2 2 2 Misuse hazards Mixing flammable gas and oxidant as result of connecting such gases at wrong inputs Mixing flammable gas and oxidant as result of not flushing the mixer a Ventilation outlets not connected while using toxic gases b Humidifier out of water Leakage Safety regulations Input Gas GI must always be inert gas that is safe to be mixed with the other gases GA and GB connected to the mixer All ingoing gases should be marked at all times a When changing input Gas A or input Gas B one must consider that there is still gas of the previously used type inside the mixer that may react with the new gas connected to the mixer Such switching is to be avoided If switching is required the user must flush the target gas input with inert gas before connecting the new gas this is described in detail later in the manual b The Mix4S selector can only be turned one step at a time The flowmeter F7 and F8 both must have at least 30mm float travel and the user must wait one minute before turning the Mix4S another step a The mixer uses bubblers to keep constant pressure conditions The bubbled gas is led to ventilation outlets If these outlets are not connected to proper ventilation they will let the gas into the room a problem if toxic gases are used b If all the water in the humidifier is spent the gas in the mixer has easier way
42. ler B1 B5 ensure that excess gas is let out and in this way maintains constant pressure conditions throughout the mixer an important feature when calculating the flow of gases through flowmeters The bubbled gas goes to ventilation There are two outlets O1 and O2 from the mixer that are meant for connection to the user cell e g to the two chambers of a ProboStat measurement cell Each outlet has a flowmeter F11 and F12 and a selection valve for inverting the output gases We repeat here the important list of gases and mixtures passing in the mixer and ask that you check that you understand the difference between them e 3Input gases GI GB G stands for Gas for Inert e 5 Mixtures Mix1 Mix5 Various mixtures from the 3 input gases e 2 Outlets O1 O2 Selected from Mix3 and Mix5 3 9 Startup and checks during initial operation first user operation training session 18 ProGasMix Manual 15 07 2013 If this is the first time you are using the ProGasMix and you have had no other training this will also function as the first step of your training and we will thus explain things as we move on 3 9 1 Mains power Connect the mixer to mains power using its external adaptor By this lights illuminate inside Moreover the Peltier element of the wetting stage box starts cooling as indicated on the temperature display 3 9 2 Initial settings of valves Check that all 12 flowmeter needle valves are closed gently turned full
43. n a pressure of 1013 25 bars a it would occupy the calibration curve reported volume 5 liters Now none of this is of much consequence to typical user as he or she is not interested in the total flows but in the ratios between the gases While interference such as changes in the laboratory temperature 28 ProGasMix Manual 15 07 2013 affects the accuracy of the total flow measurement it affects all the flowmeters roughly the same keeping the ratios between flows much less prone to error If however the total flow volume is of interest it is not enough to know if the flow is denoted in standard or normal liters but actually to know which temperature and pressure these standard or normal conditions refer to Worldwide the standard or normalized condition for pressure is variously defined as an absolute pressure of 101 325 Pascal 1 0 bar 14 73 psia or 14 696 psia and the standard or normalized temperature is variously defined as 68 F 60 F 0 15 C 20 C or 25 C There is in fact no universally accepted set of standard conditions and these differences can cause tens of percents of errors But in short the flows and calibration curves handled by the software and these issues are of no concern to normal user 29 ProGasMix Manual 15 07 2013 4 6 2 Flowmeter mixing ratios general overview It is suggested that the reading of the floating ball is taken at the m
44. nt panel in the unlikely case of explosion inside the casing acts as muffler for pressure and possible glass shards The polycarbonate front panel does not fracture into dangerous shards 2 5 Additional safety considerations Application of input pressures higher than 15 bars may lead to damage and to leakage in the tubing and pressure control parts Apply input gases at pressure above 2 bar a and not exceeding 15 bar a The mixer has built in pressure reducers set to reduce input pressures to approximately 1 2 bars a which is sufficient pressure to operate the mixer Corrosive gases NH3 SO are examples of gases that will corrode and destroy the ProGasMix Refer to PGM specifications sheet for material info When operated according to the rules it is not possible to continuously mix gases that from flammable or explosive mixtures However should inflammation or explosion take place the ProGasMix has been designed with a minimum of volume and of glass parts so that the size and consequence of such inflammation or explosion will be small and contained in the casing Not dangerous but inconvenient event called back suction risk is explained later in the manual 11 ProGasMix Manual 15 07 2013 2 6 Equipment classification Pressures in the mixer are near atmospheric except at the inputs before the pressure reduction valves Regulations for pressure equipment does not apply to ProGasMix as the volume between the inputs an
45. nts evaporation and back diffusion of water vapor but requires more care to avoid back suction in case of e g rapid cooling of the furnace In any case these couple of cms of outlet overpressure again reduces the pressure gradient and flow out of the output stages of the ProGasMix 4 3 Economic use of gases 4 3 1 Output flows Consider how much gas flow you need Equilibration in wet air or when pH O does not matter for these gases or in good buffer gases like CO CO mixtures or H H O Ar mixtures require little gas Turn the output flow down and reduce the flow through the mixer correspondingly see below If on the other hand the gas has the purpose to provide inert and or dry conditions a higher flow sometimes even as high as possible helps to minimize the effects of permeability back diffusion and leakages Remember still that flushing out a dead end of the mixer tubing or cell may be equally effective and much more economic than a lengthy high flow Other cases where high flow is required are in supplying electrodes and surfaces in high drain applications where constancy of gas composition is desired in certain types of fuel cell reactor and gas separation membrane tests are made Also transients recorded after e g a change in gas composition may require flow as high as possible 4 3 2 Backwards reduction of flows for mixtures When the output flows have been set it is good practice to regulate in backw
46. o flows and the conversion is done with the help of calibration curves The relationship between flow and float travel is a non linear complex function that includes tube size float weight gas density and gas viscosity It is additionally greatly affected by temperature of the input gas and pressure in the tube The tube and float types are known the pressures inside the mixture are known all the user needs to do is to feed the float travels and the type of gas used to the software and it will calculate the actual flows of gases and mixtures using the calibration curves obtained with range of typical input gases The GasMix program will correct for the temperature difference the gas species and so forth based on the provided information 4 6 1 Additional details on absolute flows The calibration curve flow is given in units of mIn min or In h The ml milliliters or liters is the volume of the gas in n normalized conditions a volume that the specific gas occupies at certain temperature and pressure These normalized conditions with ProGasMix are 0 and 1013 25 mbars atmospheric pressure For example the ingoing gas may be 27 C and the pressure in the flowmeter is 1 03 bars a but the actual flow is reported in normalized conditions Let us say the float travel and calibration curve would indicate 5 In h If the measured flow of gas was to be captured for a specified time say one hour Only if the captured gas was cooled to O C and give
47. out through the refill line than through the rest of the mixer To prevent this the refill lines are connected to the ventilation lines In case of using the mixer with toxic gas the ventilation outlets must be connected to a working ventilation system each ventilation outlet as its own separate line In case of a leakage the main risk is posed by odorless toxic gases such as CO If such gases are used extra warning labels should be placed on the mixer A corresponding gas detector with sound alarm must be used to guard against the possibility of a leakage or user error 2 2 2 1 Additional information on safety regulation 2b The valve Mix4S allows selecting the source gas for mixture 4 One may select either the mixture 2 or input Gas B Now it is possible that the mixture 2 might be undiluted input Gas A possibly a fuel type gas The input Gas might be an oxidant White the Mix4S valve effectively cuts off one feeds the other one to flowmeter F7 and prevents continuous mixing of Gas A and Gas B there will be gas of the previous selection inside the system that will get into contact with the new 10 ProGasMix Manual 15 07 2013 selection For such reason on the four step selector the two positions between Mix2 and GB are both connected to the inert gas The user has to go over the GI selection wait with it and thus flush with inert gas when operating according the safety regulation 2b 2 3 Safety recommendation
48. owness causes 3 6 Connection of input gases Connect input gases to the inlets at the front bottom of the mixer Use only quick connects with valves so that they close upon disconnection and open when connected Some quick connect counter pieces are supplied with the mixer and the part number is included in the specifications of the mixer if more are needed Mark the input gases GA GI and GB appropriately and clearly GI stands for input Gas Inert so never connect oxidant or fuel type gases on input This is clearly marked on the mixer Input GA has capacity for much larger dilution than GB In case of fuel cell type mixing typically connect the fuel to GA and oxidant to GB Never connect a new type of gas to GA or GB without first connecting an inert gas to the input first and running the mixer for few minutes with significant gas flow to flush out the old gas 3 7 Connection of outlets to measurement cells 17 ProGasMix Manual 15 07 2013 Connect any mixer outlet O1 and or O2 to any measurement cell chamber The connection should use same type of quick connect than the gas inputs Use valve OS to select which way the Mix3 and 5 is connected to O1 or O2 This allows user for quick inversing the gases without stopping the gas flow 3 8 Learn the principles and terms of gases and mixtures In order to operate onwards you need to know and understand some simple principles of what the mixer does and how we denote the gases an
49. ows for drying stages to be installed Useful location for drying stages would be between Mix3DS and F6 and between Mix5DS and F10 for mixtures 3 and 5 respectively A suitable model will not cause pressure drop of more than few millibars Be aware that the molecular sieves absorb CO in addition to water so that gases containing CO as a component should have a way to bypass the installed drying stages This can be achieved with similar selection mechanism as with the wetting stages One recommended model is microporous absorbent namely SGE analytical moisture trap model 103487 Under normal temperatures and the flows ProGasMix has it removes 20 down to 10ppb and is expected to absorb about 12g of H20 16 ProGasMix Manual 15 07 2013 The drying stages have a certain capacity to absorb various gases That means that a flow of 2 will initially get some O2 absorbed until the surfaces are saturated After some flow it should stabilise at the correct ratio As with water absorption will continue until the capacity of the stage is reached The same effect also applies to any other desiccant and also to the wetting stage The liquid water has a capacity to dissolve gases which will make any change in the gas composition take a little time to stabilise We recommend using the drying stage only when very dry gas is critical 3 5 6 Connection of ventilation and overpressure outlets The mixer uses bubblers to keep constant pressure level
50. r which there is a significant gradient and transport number In the following the equation is solved under the assumption that there is a gradient in only one species and that the gradient is small so that the transport number can be considered constant whereafter the integration leads to z Y v 5967 Gt where Ey is the Nernst voltage Finally 26 ProGasMix Manual 15 07 2013 The software that comes with the ProGasMix will calculate the Nernst voltages involved after you have entered the readings of the flowmeters and will then give transport numbers based on the voltages measured With the ProGasMix one may measure the transport number as a function of the gradient i e the Nernst voltage and extrapolate back to zero gradient to obtain the transport number closest to the assumption of a small gradient However making too small gradients will inevitably lead to immeasurably small voltages and consequently scatter in the transport number curve Below we give some examples of types of gradients and how they are obtained in the ProGasMix However first we discuss how you can measure small voltages by minimising or eliminating background offset voltages 4 5 7 2 Background offset voltage minimization and elimination Use identical materials for electrodes and make sure there are no thermal gradient over the sample All junctions and transitions from one type of lead to another type must be identical in material and of tempera
51. s The main risk is misuse therefore the access to the mixer should be restricted to qualified persons Each person with access to the mixer should understand the properties of all gases they are going to use The users should be obliged to read the manual especially this safety sheet and all accompanied documents and to sign that they have done so using the table at the end of this document 2 4 Non hazardous aspects and built in safety features There are no residual hazards with ProGasMix It is built from metal glass silicon O rings and so on The most exotic component ProGasMix contains is Halocarbon 6 3 oil which is completely inert and non toxic Material safety sheet for the oil is included with the ProGasMix shipment Otherwise ProGasMix contains only what the user feeds into the mixer such as distilled or de ionized water and the gases of user s choice The gas flow is controlled with manual flowmeters and manual valves and the mixer does nothing else than allows different gas species to mix thus the mixer does nothing else than what naturally occurs when mixing gases in general and therefore there are no other hazards that what the mixing itself poses a responsibility of the user In case of system damage and a leakage the mixer is built in a well ventilated construct Volumes and pressures are small and the majority of the construct is non flammable The mixer is contained in a non gastight metal frame with a polycarbonate fro
52. s and the gas through the bubbler is vented out This section describes how and where to connect the outlets that dispose of surplus gas VentA is connected to the bubblers and wetting stages using input gases GA and and the VentB is connected to bubblers and wetting stages using gases and GB Both the VentA and VentB lines must be led out to ventilation as separate lines Identify the outlets VentA and VentB It is in principle not necessary to connect these outlets anywhere if the mixer is not used for gases that pose any risk or smell but if there is even a slight possibility that such gases may be used in the future or by accident the ventilations must be connected as instructed If still used to lead the gases to a hood or ventilation system lead both outlets as separate lines do not merge them at any point The ventilation must be an active one a fan or a pump it is not enough just to lead the vent lines out of the room The materials and connections used after the bubblers are not considered high grade gas tight it is the slight under pressure created by the ventilation machinery that makes sure the gases stay inside the ventilation lines and are led out of the system Important Do not use quick connects with built in valves and do not use any other valves that may be deliberately or accidentally closed these outlets must be kept open at all times Also do not use too narrow hose or tubing due to the pressure drop narr
53. s may be considered 4 4 Wetting stage control The temperature of the wetting stage defines the vapor pressure H20 and thus the maximum possible pH O of your mixtures The higher temperature used here the higher pH O possible If however the ambient temperature goes close or below the temperature inside the wetting stage the moisture begins to condense in the gas lines this interferes with gas flow renders the calculations wrong and causes other kind of trouble We recommend selecting a temperature of two degrees below the lowest foreseeable laboratory temperature and setting the wetting stage for that with 1 hysteresis Small difference from ambient also prolongs the life of the wetting stage fans The cooling power and the insulation are sufficient to cool the wetting stage roughly 10 below the ambient temperature at 25 At higher ambient temperatures the gain might be less In case no fluctuation in is acceptable we recommend turning the cooling hysteresis to 0 5 C When higher water vapor contents are required external humidification stage can be used NorECs builds such devices and also offer gas line heating solutions as well as ProboStat base unit heating systems 4 4 1 Wetting stage temperature and vapor pressure of H O Temp 8 9 C Wc 1486 nc wc Mme 1565 155 ic 1 1566 AoE kPa 1 073 1 148 1228 1 313 1 403 1 498 1 599 1706 1819 1938 2 064 2 198 2 339 Temp 21 22 23 24 25 C 26 27 28 29 30
54. s of transport numbers One may for instance plot the transport number vs ratio or log ratio of partial pressure and extrapolate back to zero gradient ratio 1 log ratio 0 One may also make differences in pH O instead by setting the wet dry mixing ratios different between Mix3 and Mix5 along similar principles Or as explained above set Mix3DS to GI and mix in dry in order to change for instance and pH without a difference in pO 4 7 4 Logarithmic variations in partial pressure The real advantage of the ProGasMix comes in the variations of e g pO over large ranges This can be done at fixed pH O and we will show here some typical series Let us start at pure O as Input gas A and mix it with Ar as Input gas After mixing in stages F1 amp 2 and F3 amp 4 it is then wetted by running at e g 65 through F7 and W1 But what are the best settings for the flowmeters F1 to FA Here is a suggestion with rough ratio estimates F1 F2 F3 FA Mix1 2 Log Mix2 65 0 max 0 10 1 0 0 50 5 max 0 1 1 1 1 0 3 20 10 max O 1 5 1 5 0 7 25 25 max 0 1 10 1 10 10 We see here that the three latter series utilizes the rule of thumb much little little little and some some gives three points per order of magnitude which may be suitable for many purposes Now instead of pressing more out of this stage and thereby wasting a lot of gas it is more economic and accurate to leave it and do the same series on stage 2
55. s under reducing conditions in gas atmospheres 4 5 6 Large gradients fuel cell and permeation tests 4 5 6 1 Fuelcells One typical use of the ProGasMix is in supplying fuel and oxidant to the two sides of a fuel cell test On the fuel side Mix3 for example H as GA on oxidant side Mix5 Air or O as GB and the inert dilutant gas Ar or as While dry H2 containing gases may seem the right for the fuel side this is often too reducing and may embrittle platinum and reduce other components Better and more stable operation is usually obtained by wetting the H mixture fully The ProGasMix can also wet the oxidant This may be a good option for work with proton conducting fuel cells of various kinds Fuel cell can be started in soft manner with large dilution or pure inert gases It is good practice to flush all parts of the mixer especially the wetting stage and bubblers with inert gas before switching to and from gases that may form flammable or explosive mixtures Special care is to be taken not to alter the position of Mix4S when using the mixer in fuel cell mode The valve selects between Mix2 pure or diluted fuel and GB oxidant While one is always cut off the small volumes in the mixer are still filled with the previous type of selection When operating valve Mix4S always comply with safety regulation 2b 4 5 6 2 Gas permeation By supplying different gases over a membrane sample analysis
56. s with bubbler liquid 3 9 6 Leakage identification and elimination Most changes in bubbler columns are due to temperature changes this is best seen when all columns change same or similar amount or in clear proportions to their overall heights If the changes are not uniform an overpressure column does not stay constant with others there may be a leakage in the region connected to it 20 ProGasMix Manual 15 07 2013 Inspect all Swagelok nuts to visually confirm that they seem to be tightened to the same level If one appears more distant from the bulk of the union or component first check with your fingers whether it is still only finger tight If the nut can be loosened check that it is otherwise OK finger tighten it and then turn 94 of a turn by wrenches If no obvious loose nut or other mistake is spotted the leaky region may be tested by applying dilute soap water preferably Swagelok Snoop to suspected joints and seals and looking for leak foam forming In this process keep the overpressure up by letting the flowmeters flow in some gas Moreover wait sufficient time to let the foam form since the overpressures are small the foam may form slowly and be difficult to spot If a leakage is spotted consider to remedy it If a nut looks slightly less than normally tightened try tightening it gently If a nut leaks but looks normally or overly tightened then open it retract the nut and check that ferrules are correctly
57. software for calculating gas mixing ratios and also equilibrium compositions resulting from gas mixers such as the ProGasMix However the program has flexibility of configuration and use that makes it useful also for other gas mixing applications 8 1 2 History of GasMix The GasMix for Windows is a development from the GasMix program written by Truls Norby for HPBASIC computers in the 1980s and used at University of Oslo till this date for calculating gas mixtures on gas mixers analogous to the ProGasMix 8 1 3 Note GasMix emulates but does not control your mixer To avoid any misunderstanding GasMix emulates the physical gas mixer and makes calculations based on the readings taken from the mixer It is however not physically connected to the mixer in any way it does not communicate with the mixer and it does not control the mixer in any way 8 2 GasMix quick start and tutorial This section intends to give the user a fast introduction to the GasMix software and practice in using it 8 2 1 Start and run the program GasMix exe Start the program GasMix exe from the shortcut icon or in any other way 8 2 2 Fundamental elements of the gas mixer and GasMix display At the bottom of the display are a row of small boxes each representing an Input gas Typical Input gases are the pure gases or mixtures that come from bottles or lines of gas in your laboratory e g O Air Ar 596 in Ar Next at middle height of the display comes a
58. strength The materials used for gas tubing and components are all qualified for the gases and pressures used and this is well proven over many years of use of preceding units over more than 20 years 7 1 2 3 Provisions to ensure safe handling and operation The ProGasMix has initial pressure reducers and continuous near atmospheric pressure relief throughout It relies on the user connecting safe gases at safe pressures Should there still be occasions of overpressure supply clogging of overpressure systems ventilation or explosion the volumes involved are small the number of glass items kept to a minimum and all such parts protected behind polycarbonate and metal casing The ProGasMix involves no voltages above 24 V It has no hot external surfaces 1 T Norby Method Determination of Conductivity Contributions from Protons and Other Foreign lons in Oxides Solid State lonics 28 30 1988 1586 91 40 ProGasMix Manual 15 07 2013 7 1 2 4 Means of examination Each ProGasMix is manually assembled It is tested for leakages before shipment Final function testing and renewed leakage testing is performed during installation after filling of the overpressure columns with bubbler liquid on site 7 1 2 5 Means of draining and venting Draining is normally not necessary for safety reasons but may be done for improved purity and correctness of gas mixtures made by flushing inert gas according to procedures in the manual Overflo
59. t and 43 8 2 1 Start and run the program 43 8 2 2 Fundamental elements of the gas mixer and GasMix display 43 ProGasMix Manual 15 07 2013 1 Introduction Welcome to the ProGasMix FC mixer instrument PGM or ProGasMix from here on manual The manual provides you first with all essential information for e Safety e Installation These parts are to be studied and used in the sequence they are provided here We consider it essential that no parts are omitted These two parts form fundamentals of the training for the user responsible of the mixer The section safety includes risk assessments and recommended safety procedures The section is also provided as two separate copies to be read and to be signed during the PGM installation one to remain always at the mixer and one to be taken back for the manufacturer Further definitions relating to instrument safety can be found in chapter 7 Thereafter we provide instructions for e Different modes of operation e Maintenance which show how the PGM is used in normal use after installation It thus forms the second part of the training intended for all users after they have been trained in safety and fundamental aspects by the user responsible Finally we provide sections of more specialized operations and maintenance We also provide a more detailed reference for safety and conformity
60. t dry gas run until the water is evaporated See also special section documentation on flowmeter maintenance and service The flowmeters are equipped with 15 turn needle valves While these can close off a flow they must never be forced and do not provide vacuum tight closure If absolutely zero flow of something is needed it must be achieved by other means 4 7 Suggestions for flowmeter settings for various uses 4 7 1 Outputs First of all let us suggest that output flowmeters F11 amp F12 are set at FT 15 mm as normal This corresponds to flows of the order of 10 ml min Reduce flow throughout when possible to save gas or increase if necessary for special needs 31 ProGasMix Manual 15 07 2013 4 7 2 Small variations in partial pressure The flow is to a first approximation proportional to the float travel The user will thus intuitively be able to set mixing with relatively linearly varying ratios For instance a pair of S and L tubes set with FTs S10 L10 mm will give a 1 8 7 flow ratio Changing to FTs S35 L10 mm will give a 1 2 5 ratio and changing FTs S65 L10 mm will give ratio of 1 0 87 4 7 3 Small differences between Mix3 and Mix5 Flowmeters F7 and F8 making Mix4 can be used to make small accurate differences between Mix3 and Mix5 for transport number studies Mix4Se gt Mix2 in such case Typically F7 may be set to 35 mm and F8 varied through 1 mm to 65 mm to measure voltages over samples and obtain a serie
61. ted and closes when the two parts are separated from each other To connect them just push the stem into the bulkhead To disconnect push the rough ferrule on the outside of the bulkhead forward and pull the stem part away 3 4 Assembly The following procedures of assembly are done with the side and rear plates still removed Assembly is normally performed by NorECs personnel on site The acronyms for valves and other parts are all marked on the mixer but it is good idea to have the flowchart of the mixer also in hand while doing these steps to better understand the inner workings of the mixer Copies of the flowchart can be found in the envelope on top of the mixer and also later in this manual 14 ProGasMix Manual 15 07 2013 3 4 1 Bubbler liquid filling In case of an on site installation of PGM NorECs person will do the filling of the bubblers Each glass tube should be marked with bubbler ID and filling height mark These should correspond approximately to heights of B1 45 cm B2 35 cm 10 cm B4 25 cm B5 10 cm Amongst the tools packed find a funnel and a piece of tubing and connect them to each other to make a convenient tool for bubbler filling Pull the bubbler caps gently up and slide the hose of the funnel to the tube Use a small intermediate container to easily dose small amounts of liquid to the bubblers After filling check visually that all levels are on or within few centimeters or so from the mark and t
62. ture as well as all cables must be identical to each other Use shielded cables and keep away from power carrying leads Use identical atmosphere on both sides to find out presence of an offset Alternatively with true atmospheres measure sample voltage reverse the gases measure the sample voltage and average voltages to find out the offset 4 5 7 3 Oxygen activity gradients Enter here 4 5 7 4 Hydrogen activity gradients Enter here 4 5 7 5 Other activity gradients Enter here 4 5 8 Transients Enter here 4 5 9 H D isotope effects Enter here 4 6 Characteristics of the flowmeters The flowmeters used in the ProGasMix are so called variable area flowmeters This reflects the variable cross section of the flowmeter tube the float in our case a small ball floats higher up larger area for passage of the gas the higher the flow The floats usually spin or rotate when they operate normally hence the flowmeters are often also referred to as rotameters The flowmeters used in the ProGasMix are of type V gtlin V 100 The tubes are borosilicate tubes with hexagonal inner to prevent the ball called float from getting stuck easily 27 ProGasMix Manual 15 07 2013 In general the tube and the float both can be of different sizes The ProGasMix utilizes three combinations or three different types of flowmeters described in table below Symbol Floatlooks Flowmeters Role Flow range air 30 Type Black F1 F3 F5 F9
63. ve an inert gas connecter to input gas Open F4 F5 F8 and F9 to large flows Set the Mix3Win Mix3Wout W1 and Mix5Win and MixSWout to W3 Leave the mixer like this for few minutes and then close the flowmeters 5 2 Procedures to optimize purity e g inertness or dryness of a gas in the mixer Previously used gases remain in the mixer specifically dissolved in the wetting stages for considerable amount of time While flushing for some minutes is enough to prevent potential hazards it does not purify the mixer completely of the previously used gases The purity of made mixtures improves over time as and as function of flow 5 3 Leak testing To be entered 34 ProGasMix Manual 15 07 2013 5 4 Flowmeter calibration In some cases for example if flowmeter is replaced with another type or an existing calibration curves does not match the requirements for example rare gas type to be used the user may be interested to enter their own calibration curves Exact details for such operation are beyond the scope of this manual but the general idea is described below Flow table or calibration curve is a table of real flows measured at given float travels typically In h per float travel To create such table the user may acquire for example V gtlin Smart series mass flow meter mfm calibrated with real gas es in question The mfm is connected to a gas line before the flowmeter and the measured flow is read from the mfms led d
64. w gases from the input vents or overpressure control columns are led to vent outlets on the unit These need normally not be led onwards to venting system unless toxic or irritating gases are used or venting is otherwise desirable 7 1 2 6 Corrosion or other chemical attack The continuous use of ProGasMix units for more than 20 years indicates that corrosion is not a problem The most corrosive gases considered that it can tolerate used intermittently over many years is wet CO and wet O no problems have been observed with these gases 7 1 2 7 Wear The only wear expected is on flowmeter valves While these can operate for many years without maintenance they may also break down due to e g over tightening user applying excessive force Preventive maintenance and repair may be done according to standard procedures issued by the flowmeter manufacturer supplied with the ProGasMix 7 1 2 8 Assemblies N A 7 1 2 9 Provisions for filling and discharge Discharging the mixer is to be done according material information and local legislation 7 1 2 10 Protection against exceeding the allowable limits of pressure equipment To be entered 7 1 2 11 Safety accessories To be entered 7 1 2 12 External fire The ProGasMix is considered of too small pressure and volume of fluids gases of Group 1 Dangerous that any special precautions are necessary in case of fire 7 13 Manufacturing To be entered 41 ProGasMix Manual 15 07 2013
65. y clockwise 3 9 3 Input gas A gas should now be connected to at least two of the three input gas lines Check that there is no gas going to any of the glass tube columns in the mixer If the columns are changing or eventually bubbling check again to close all needle valves on the flowmeters by turning clockwise to a gentle stop 3 9 4 Flowmeters and overpressure bubblers Flowmeter has fine valve and a flow indicator a small ball in a hollow glass tube The higher the ball the more gas is flowing The height of the ball is called float travel and it is announced in millimeters and read from the scale printed on the tube Now turn flowmeter F1 up to a flow corresponding to say 50 mm float travel This is fed from input gas GA By this the column on overpressure controller B1 starts to slowly move downwards gas goes down in a hollow glass tube against the pressure of the liquid in the external glass tube pushing the liquid away making a visible indication of the flow Turn also flowmeter F2 up to flow corresponding to say 50 mm float travel This is fed from Input gas F1 and F2 mix gases GA into what becomes 1 F1 has a light glass float and supplies relatively small flows F2 has a heavy steel float and contributes ca 10 times as much gas as F1 at the same float travel height Soon B1 will have reached the end of the column and starts to bubble This is the normal operational mode it keeps th
66. y to be below any possible ambient laboratory temperature eliminating risk of condensation of the wetted gas in the gas lines 3 5 3 Fill the wetting stages The mixer may be shipped with distilled water in the wetting stages but it is good idea to familiarize with this process anyway Before refilling make sure the wetting stage W1 has an open outlet put Mix3Wout to W1 open F11 and F12 by turning it gently counter clockwise at least ten full turns or until you feel a resistance Make sure the outputs have quick connect stem on them to open the valve on the quick connect bulkhead 15 ProGasMix Manual 15 07 2013 Remove the cap on wetting stage refill W1re and add distilled or de ionized water until the level indicator W1 reaches mark Max1 Place back the cap W1re Make sure the wetting stage W3 has an open outlet put MixbWout to W3 Remove the cap on wetting stage refill W3Re and add distilled or de ionized water until the level indicator reaches mark Max1 Place back the on W1Re Select original positions for Mix3Wout MixSWout and close the F11 and F12 3 5 3 1 Maintenance of the wetting stages Fill water as required even during the operation but in case using toxic gases involved be aware that the refill lines are in direct contact with the vent lines and if the vent lines are not connected to actively working ventilation the vent gases will come out of the mixer where the resistance is the least the refill

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