User Manual Directions for use reference Electrodes
Contents
1. NOTE reference electrodes types SR20 A 2 in flow Before installation all the above mentioned immersion or other fittings is similair to that for items must be removed In addition reference glass electrodes see directions for use of glass electrodes with polished sleeve junction types electrodes or figure 8 SR20 AS52 will need to have their polished ends telescoped into each other If required When mounting the Bellomatic reference the flow electrodes may be connected to a electrodes a special holder is required reservoir of electrolyte solution To maintain a correct flow the reservoir must be placed so that Part number FP20 D S13 stainless steel for the pressure at the inner side of the diaphragm mounting in electrode fittings with the type number Fig 12 K1S00DW set of 12 cable nuts ae BEAP SR20 SR20D K1500BY FP20 S13 FP20 S13D x Z 25 lt RING M 25x1 5 K1500HC 7 O Ring 10x4 T5 K1 e Hi y iodho lt 2 28 cb m PG13 5 A 33 28 SM 25x15 S Figure 8 Standard mounting options Fig 9 Mounting PG13 5 in Yokogawa fitting using the adapter K1520JN PVC C or K1500DV PVDF Figure 10 SR20 AC52 SR20 AS52 Figure 11 Mounting kit SR20 AC322. 3F Tower D Cartelo Crocodile Building No 568 West Tianshan Road Changing District Shanghai China www yokogawa com cn YOKOGAWA EUROPE B V Euroweg 2 3825 HD Amersfoort The Netherlands www yokogawa com eu YOKOGAWA MIDDLE EAST B S C c P O Box 10070 Manama Building 577 Road 2516 Busaiteen 225 Muharraq Bahrain www yokogawa com bh Yokogawa has an extensive sales and distribution network Please refer to the European website www yokogawa com eu to contact your nearest representative YOKOGAWA User Manual Directions for use reference Electrodes YOKOGAWA IM 12B6J1 10E E 0701012 A Printed in The Netherlands Subject to change without notice Copyright 1 GENERAL 1 1 General spec s for NON Flow electrodes e Maximum process pressure 500 kPa 5 bar e High quality Ag AgCl reference system pin which can stand high temperatures and temperature fluctuations SR20 D AC22 e Temperature pressure variation compensation e To be used in non polluting fluids e Saturated KCl solution pellets e For low ionic applications and high temperatures e Temperature range O to 120 C e Diaphragm resistance 25 C lt 10kQ SR20 D AP24 e General purpose PTFE diaphragm electrode e Large PTFE diaphragm e Thickned KCl solution 3 3m e Temperature range O to 80 C e Diaphragm resistance 25 C lt 10kQ SR20 D AP26 e When KCI is prohibited in the appli
3. is recommended to fill the electrode with a reference liquid having a higher viscosity ordernrs K1500GG 1m or K1520VN 3 3m SR20 D AS52 e Sleeve junction is suitable for pure water applications and very strong polluted liquids e Maximum process pressure 100 kPa atm e Temperature range O to 100 C e Diaphragm resistance 25 C lt 10 kQ e Flow Rate at 25 C 5 0 ml day at 10 kPa overpressure 1 3 TYPE NUMBER The type number of a reference electrode as indicated on the type plate is arranged as follows SR20 D liquid outlet 2 non flow 22 PTFE hose filled with KCI pellets 24 filled with gelled electrolyte 26 double junction filled with gelled electrolyte 1 flow laboratory use 3 flow process pressure compensated 5 flow 52 refillable at the top diaphragm C ceramic P PTFE porous S sleeve reference system A Ag AgCl silver silver chloride 1 4 SPECIFICATIONS The specifications the temperature application range the reference system etc of an electrode are all clearly shown on the electrode cap type plate The resistance of the diaphragm depends on the type of the electrode but must be maximum 10 kohm at 25 C in all circumstances 2 INSTALLATION 2 1 PREPARATION FOR USE When dispatched the reference electrode has a protection sleeve around the diaphragm Flow electrodes types SR20 52 have a refill opening which is sealed with a cap The inner duct of t
4. 3 USE AND MAINTENANCE During a measurement with reference electrodes there must be good electrical contact between the reference system and process liquid To guarantee this electrical contact it is necessary to ensure there is sufficient electrolyte solution in the electrode or in the electrolyte reservoir In circumstances where the concentration is not stated on the type plate a saturated KCI solution of KCI in demi water should be used to refill the electrode When the concentration is stated e g Ag 3 3m the electrode must be filled with 3 3 molal KCI Order a 3 3M solution by part number K1500VA Types SR20 D 2 The electrodes of this type are filled with a gelled electrolyte solution and refilling is not necessary When there is insufficient electrolyte solution the electrode has probably been used at too high a temperature and therefore replacement by another type of reference electrode is recommended Types SR20 D AC32 To refill electrodes of this type a vacuum pump must be connected to the bottom of the electrode Figure 13 On removing the electrode cap the pump will contract the bellow and refilling with electrolyte solution can be made ATTENTION The pump may be removed after replacing the electrode cap It is recommended to replace the O rings part number set of 5 O rings K1500GE If no vacuum pump is available unscrew the electrode cap Press down the bellow by means of a clean rod with a round to
5. cation e Double junction thickened KNO in buffer compartment Large PTFE diaphragm against pollution Thickened KCl solution 8 3m Temperature range O to 80 C Diaphragm resistance 25 C lt 10kQ _ 2 General spec s for Flowing electrodes Liquid flow output preventing diaphragm fouling and poisoning the reference system High quality Ag AgCl reference system pin which can stand high temperatures and temperature fluctuations e 3 3m KCI electrolyte SR20 D AC32 e Automatic compensation for process pressure variations e Constant flow of reference liquid independent of the process pressure variations for minimal diffusion potential 0 5ml day e Suitable for pure water applications and for polluting fluids e Refillable large KCI reservoir e Maximum process pressure 1000 kPa 10 bar e Temperature range O to 120 C e Diaphragm resistance 25 C lt 10 kQ G14 G14 2 ry z re 3 17 gt 12 S gy 12 gt Flexible __ PTFE tube 12 gt 8 5 aS a a 17 gt 12 gt 120 os ez y Fig 4 SR20 AC1 k Fig 5 SR20 D AC32 NOTE The flow is highly dependent on temperature When using the electrode continuously at temperature over 70 C it
6. he process pressure compensated Bellomatic electrodes type SR20 AC32 is provided with a rubber plug Do not throw away the rubber plug as it is needed for re filling exceeds the process pressure for open systems the level of the electrolyte must be above the level of the measuring liquid Only under these circumstances will correct electrical contact between reference system and measuring liquid be guaranteed 2 2 MOUNTING The reference electrode must be connected to an electrode cable type WU20 D PC marked with a yellow strip The method of mounting certain types of FF20 FS20 FD20 The electrodes fit any Yokogawa cable fitted with the standard nut shown in figure 12 The nut has order number K1500DW The sensors with D CAP fit into all our fittings when using the adapter K1500DV PVDF or adapter K1520JN PVC The SR20D AC32 needs a mounting kit when mounted into our fittings One is specifically for the Y cap FS20 S13 another for the D CAP FP20 S13D The SR20 AS52 and AC52 also need a mounting kit to fit into a pH fitting regardless if it is a D or Y CAP K1500BY With the FD20 FF20 FS20 fittings this mounting kit can be ordered as an option option R Yokogawa has her own specific cap Y CAP The process connection for this cap is M25 and can be mounted in all the fittings that are available in our program Secondly we have the D CAP which has a PG13 5 process connectiont
7. m can give deposits which block the diaphragm e g silver chloride sulfide gt deposits of silver sulfide When poisoning occurs replacement of the electrode will normally be necessary It is recommended if poisoning of non flow electrodes occurs to use another type of electrode d poor conductivity of the process liquid When the electrical conduction of a process liquid is very low an unstability of reading will occur This problem may be cured by adding electrolyte solution to the process liquid or by making the reference input of the measuring instrument high impedance 6 CHECK A quick check for correct functioning of a reference electrode can be made by connecting the electrode to the reference input of a pH meter A known good reference electrode with the same reference system should be connected to the glass electrode input After immersing both electrodes in a buffer solution the reading should be stable The reading must be adjustable to pH 7 by means of the zero potentiometer ass pot If this is possible the reference electrode is functioning correctly YOKOGAWA ELECTRIC CORPORATION World Headquarters 9 32 Nakacho 2 chome Musashino shi Tokyo 180 8750 Japan www yokogawa com YOKOGAWA CORPORATION OF AMERICA 2 Dart Road Newnan GA 30265 USA www yokogawa com us YOKOGAWA ELECTRIC ASIA Pte LTD 5 Bedok South Road Singapore 469270 Singapore www yokogawa com sg YOKOGAWA CHINA CO LTD
8. p to prevent for damage of the bellow Close the bottom end of the electrode with the enclosed rubber plug After removing the rod the electrode can be filled with electrolyte solution Mount the electrode cap and remove the rubber plug 4 STORAGE When a reference electrode is to remain unused for a long period it is necessary to fill the electrode completely with electrolyte solution to close the refill opening and to protect the diaphragm against drying out by fitting the protection sleeve This protection sleeve must also be filled with electrolyte solution BELLOW DOWN REMOVE ELECTRODE CAP YOKOGAWA In AIR OUT VACU ner duct UM Electrolyte BELLOW DOWN 3 Figure 12 Refill Bellomatic SR20 D AC32 Electrodes of type SR20 D AC32 have an inner duct figure 12 which contact the bellow with the process liquid This duct must be sealed with the rubber plug With the electrodes types SR20 AS52 the b sleeve must be loosened and lifted The hole in the fixed part must be closed by means of a protective sleeve or tape 5 FAULTS Generally faults are caused by a leakage to earth Fault indications can be expected when the resistance between reference system and screening falls below 10 ohm When a fault occurs first check if the electrode cable is in good condition and if the connector contacts and the terminals in the measuring instrument o
9. r connection box are clean and dry diaphragm fouling Strongly polluted liquids can cause the diaphragm to foul very quickly As a result there will be a transition resistance over the diaphragm When this resistance exceeds 10 Q there will be instability and faulty indication of the measured value The above particularly occurs with flow type electrodes when the outlet flow of electrolyte solution is too low e g with adverse pressure variations due to the medium pumps or too low electrolyte level Fouled electrodes can be cleaned with hot water in conjunction with a domestic washing solution if necessary When the fouling is caused by fat or hydroxides lime cleaning by means of an organic solvent or diluted acid respectively is recommended The diaphragm of electrodes with a ceramic diaphragm types SR20 AC can be cleaned by rubbing it on emery paper Electrodes with a sleeve types SR20 AS52 can be cleaned after lifting the loose part It may be necessary with non flow electrodes types SR20 AP2 to place the electrode for some time in an electrolyte solution of 80 C The electrode must remain in this solution untill this solution has completely cooled c poisoning A reference electrode can be poisoned by the penetration of the process liquid or by diffusion of components of the process medium through the diaphragm In addition the inner liquid in combinations with dissolved particles from the process mediu
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