INSTALLATION-USE-MAINTENANCE MANUAL FOR BOURDON
Contents
1. accidentally be applied or in which low pressure gauges may be installed on high pressure couplings Systems in which interchangeable E724 A4272 pressure gauges may give rise to A4274 dangerous contamination Systems containing toxic or radioactive A4274 fluids in a liquid or gaseous state Systems which produce mechanical A4275 A4276 vibrations E722 A4362 A3352 Systems with an operating temperature that differs from the ambient temperature NF20 In systems containing compressed gas it is advisable to select an instrument equipped with an adequate safety device In the event of unexpected failure of the measuring element the safety device allows the compressed gas to escape outside the case thereby preventing the instrument from fracturing The safety patterns employed on LEITENBERGER instruments are designated type S1 when they consist of a release valve which opens when the pressure inside the sealed case exceeds an established safety limit putting it in communication with the outside and are designated type S3 when the safety consists of an entire blow out back and there is an added baffle wall separating the measuring element from the clear solid front providing further protection to the operator Select an instrument with an adequate level of protection consulting the following tables Tab 1 2 TABI Pressurised LIQUID Safetycode 0 0 0 0 S1 51 Si St Tab 2 Pressurised GAS OR STE2. protected from moisture in this case no special attention is required If the instruments are packed in special materials wooden crates lined with tar paper or barrier bags it is preferable to store them in a closed room if possible or in any case in an area protected from the elements the condition of the packed materials should be checked every 3 4 months especially if the crates are exposed to the elements The temperature of the storage area should be between 20 and 65 C except where otherwise specified on the catalogue data sheets WARNING Improper use may damage the instrument resulting in failure and possible injury to persons or damage to the plant Carefully read the above instructions before using this product
3. AM fluid Case filling Liquid filled Safety code _ 0 s2 s1 s3 i s2 St 53 E723 Dynamic or cyclical pressures These are generally encountered when the instruments are installed on pumps and result in a significant reduction in the lifetime of the measuring element and the amplifying mechanism of the pressure gauge Such pressures are generally indicated by broad fluctuations of the pointer It is necessary to minimise this type of pulsating pressure by fitting a snubber between the source of the pressure and the instrument Filling the case with a damper liquid can also reduce the harmful effect of pulsations on the moving parts of the pressure gauge Incorrect selection of the instrument may result in fatigue failure A4271 Fatigue Failure This is caused by mechanical stress resulting from the pressure and takes the form of a small crack from the inside to the outside generally along an edge Such failures are more dangerous when the measured medium is a compressed gas rather than a liquid Fatigue failures release the fluid gradually and therefore the case pressure build up is indicated by the opening of the relief valve When measuring high pressures the process operating pressure is close to the maximum permissible stress limit and can therefore result in an explosive failure In this case a choke should be fitted on the instrument s coupling in order to limit the flow of liquid E724 Overpressure
4. Any overpressures subject the measuring element to stress with a consequent reduction in its lifespan and accuracy It is therefore always advisable to choose an instrument whose full scale pressure is greater than the maximum operating pressure so that it is better able to withstand overpressures and pressure surges Pressure surges can be handled in the same way as pulsating pressures Overpressures of longer duration can be handled by installing a pressure reducing valve on the pressure gauge line The occurrence of even a single overpressure event can result in an overpressure failure A4272 Overpressure Failure This is caused by application of internal pressure greater than the rated limits of the measuring element and can occur when a low pressure gauge is installed on a high pressure system The effects of this type of failure generally more serious in compressed gas applications are unpredictable and may result in instrument fragments being projected in all directions The opening of the safety device on the case does not always guarantee containment of the fragments It is generally accepted that using an instrument with a solid front and blow out back reduces the possibility of fragments being projected toward the front of the instrument where the operator stops to take readings The clear front alone does not provide adequate protection and in fact is the most dangerous component in such a case Overpressure pulses of short dur
5. DRUCK amp TEMPERATUR Leitenberger GmbH www Leitenberger com E Mail DT Export Leitenberger de INSTALLATION USE MAINTENANCE MANUAL FOR BOURDON TUBE DIAPHRAGM CAPSULE PRESSURE GAUGES Brand LR GERMANY LR instruments are designed and constructed to comply with the safety requirements prescribed by the international regulations in force Under the terms of directive 97 23 EC P E D LEITEN BERGER pressure gauges are classified into 2 categories PS lt 200 bar these instruments do not have to meet the essential safety requirements but must only be designed and constructed in accordance with Sound Engineering Practice and are not required to bear the CE mark PS gt 200 bar these instruments must comply with the essential safety requirements prescribed by the PED are classified as Category 1 and certified according to Form A They must bear the CE mark illustrated below CE The recommendations are excerpts taken from the text of the EN837 1 2 3 and ANSI B40 1 standards which the user must be familiar with in order to safely put the instruments into service Safety results from the careful selection and installation of the instrument in the pressurised system as well as from compliance with the maintenance procedures set out by the manufacturer The user is entirely responsible for ensuring correct installation and maintenance The persons charged with the selection and installation of the instrument must be able to r
6. ation spikes can occur in pneumatic or hydraulic systems especially when valves are opened or closed The amplitude of such pulses can be many times the operating pressure and the great speed at which they occur prevents them from being read out on the instrument making them invisible to the operator They can result in definitive breakage of the instrument or a permanent zero error A choke reduces the amplitude of the overpressure spike that reaches the measuring element The use of a pressure limiting valve protects the instrument from all pressures which exceed the calibration limit of the valve thereby protecting the instrument form overpressures A4331 The measuring element is generally characterised by its thinness and therefore works under considerable mechanical stress Chemical compatibility with the pressure fluid must therefore be taken into account None of the commonly used materials can be considered immune to chemical attack and various factors can influence its extent Concentration temperature and the type of mixture of the various chemical substances Chemical attack can rapidly lead to corrosion failure A4273 Corrosion Failure This occurs when the material of the measuring element is weakened through attack by the corrosive chemicals present either in the media inside or the environment around it Failure may occur as a pinhole leakage or early fatigue failure due to stress cracking brought about by the chemica
7. e A4276 Vibration Induced Fatigue Failure Large amplitude vibrations may in some instances cause fatigue cracks in the structure of the measuring element In this case the pressure build up may be slow or fast or even explosive E722 Vibrations When the pressure gauge support is subject to vibrations various solutions may be considered such as a the use of liquid filled gauges b if the vibrations are strong or irregular the instruments must be mounted at a distance and connected using a flexible hose or tubing The presence of vibrations is indicated by continuous often irregular fluctuations of the pointer A4362 Liquid filled Cases Liquid filling is generally used to dampen the vibrations of moving parts due to vibrations and or pulsations Great care must be taken in choosing the damping liquid for instruments that will be used with oxidising media such as oxygen chlorine nitric acid hydrogen peroxide etc In the presence of oxidising agents there is the possible risk of chemical reaction ignition and explosion of the instrument In this case it is necessary to use fluorine or chlorine based filling liquids In order to contain the damping liquid inside the case the pressure gauges are built and supplied in a sealed construction In some cases during installation it is necessary to ventilate the case following the instructions on the label affixed to the instrument itself Special care must be taken wi
8. ecognise the conditions that may negatively impact on the instrument s ability to perform its function and which may lead to premature failure In order to correctly specify the functional and constructive characteristics of the instruments it is recommended to consult the most up to date version of the catalogue data sheets available on line at the website http www Leitenberger com SELECTION CRITERIA A431 Operating pressure range The instrument selected should have a full scale pressure range such that the operating pressure occurs in the middle half between 25 and 75 of the scale The full scale pressure of the gauge should be approximately two times the S N intended operating pressure A black S triangle symbol on the scale end of the dial indicates that the operating pressure may reach 90 for pulsating pressures and 100 for static pressures A424 The following applications must be considered potentially dangerous and carefully specified Paragraph NF20 A4274 A4274 A4331 A4273 A4274 Application Systems containing compressed gas Systems containing oxygen Systems containing hydrogen or fluids diffused with hydrogen Systems containing corrosive fluids in a liquid or gaseous state Pressurised systems containing explosive or flammable fluids Systems containing pressurised steam Systems subject to dynamic or cyclical pressures Systems in which overpressures may NF21 E723 A4271
9. h care to avoid pressure surges or sudden changes in temperature Shut off valves must therefore be opened slowly USE A432 It is not advisable to use the instruments for measuring pressures near zero as in that range the accuracy tolerance can represent a significant percentage of the applied pressure For this reason these instruments should not to be used for measuring residual pressures inside large volume containers such as tanks surge tanks and the like In fact such containers may retain pressures that are dangerous for the operator even when the instrument indicates a zero pressure It is recommended to install a ventilation device on tanks in order to achieve zero pressure before removing covers or connections or performing similar tasks E7251 Ambient Temperature It is difficult to insulate the instrument from ambient temperatures that are too high or too low One solution is to position it further away from the source of cold or heat when this is possible If an instrument of accuracy class 0 6 or higher is used at an ambient temperature different from the reference value 20 C 2 C it is necessary to make a correction A44 It is not advisable to successively install instruments on systems with different operating media to avoid initiating chemical reactions that may cause explosions resulting from contamination of the wetted parts NF45 If the instrument dial indicates a fixed pressure for a prolonged t
10. ime make sure this is not due to an obstruction of the pressure element supply pipe Especially in the case of a zero pressure reading make sure that there is effectively zero pressure inside the instrument before removing it by isolating it using the shut off valve MAINTENANCE E9 The general safety of an installation often depends on the operating conditions of the instruments which it contains It is essential that the measurements indicated by these instruments are reliable Therefore any instrument which appears to give an abnormal readout should be removed checked and recalibrated if necessary Maintenance of accuracy should be confirmed by routine checks Checks and recalibrations must be carried out by competent personnel using suitable testing equipment NF40 Every 3 6 months after installation check the accuracy and the wear on moving parts and the state of corrosion on the measuring element For instruments used on plant subject to demanding conditions vibrations pulsating pressures corrosive media sediments etc replace them after the time intervals indicated in the plant procedures A4332 The calibration and testing fluid must be compatible with the measured media in the pressurised system Fluids containing hydrocarbons must not be used when the measured medium is oxygen or any other oxidising substance NF41 Instruments kept in their original standard packing cardboard box must be stored in a closed area and
11. ing the instrument during the initial pressure rise The fluid should not be allowed to freeze or crystallise inside the measuring element However if the instrument is used for measuring points at high temperature it is recommended to use a hose with inside diameter of at least 6 mm to connect it to the pressure coupling A hose about 1 5 2 metres long reduces the effective operating temperature to approximately ambient level If the type of fluid does not permit the use of a small section hose it is often necessary to insert a separator between the process fluid and the instrument provided that the transmission fluid is suitable for the temperature of the process fluid NF22 The characteristics of the instruments may be affected during transport despite adequate packing and must be checked before use Correct calibration can be checked by excluding the instrument from the process by means of the shut off valve and checking that the pointer returns to the zero mark unless the temperature varies greatly from 20 C Failure of the pointer to return to zero indicates serious damage to the instrument INSTALLATION E71 To facilitate removal for maintenance purposes a shut off valve can be installed between the pressure gauge and the plant The pressure connection must be watertight If the pressure connection has a cylindrical thread the seal is achieved using an O ring clamped between the two flat sealing surfaces one on the press
12. l deterioration of the material In such a case the use of a fluid separator made of suitable material must be considered However the addition of a separator may influence the sensitivity or accuracy or both As an alternative to a fluid separator it is possible to consider choosing a measuring element made from AISI316 or Monel 400 rather than phosphor bronze A4274 Explosive Failure This occurs as a result of the violent release of thermal energy due to a chemical reaction such as adiabatic compression of oxygen in the presence of hydrocarbons It is generally accepted that the effects of this type of failure cannot be anticipated Even the use of solid front instruments does not esclude against the projection of fragments toward the front of the instrument Pressure gauges suitable for use with oxygen are marked Oxygen Use no Oil and or with a crossed out oil can symbol on the dial The instruments are supplied already washed OXYGEN and degreased using appropriate products and packed in polyethylene bags The user must take the necessary precautions to ensure that the connection and the elastic element are kept clean after the pressure gauge has been unpacked A4275 Vibration Failure The most common mode of vibration failure is that where the movement parts wear because of high cyclic loading caused by vibration resulting in a gradual loss of accuracy and ultimately failure of the pointer to indicate a pressure chang
13. th the type of filling liquid used and its usage limitations as a function of ambient temperature Tab 3 Filling liquids Ambient Temperature Glycerin 98 15 65 C 60 150 F Silicone Oil 45 65 C 50 150 F Fluoridated Liquid 45 65 C 50 150 F A3352 In case of radial mounting especially if the case is filled with damping liquid and the vibrations are extensive the possibility of failure resulting from the considerable vibrating mass of the pressure gauge must be taken into account In such cases a threaded 1 2 coupling to the process line is an essential minimum requirement E721 Mechanical stress Pressure gauges must not be subjected to mechanical stress If the installation points are subject to mechanical stresses the instrument must be installed at a distance and connected using flexible hoses The instruments selected must be of the surface wall or panel mount type NF21 Regardless of the material with which the unit has been made or welded connection to the process Bourdon tube terminal it is not advisable to use the pressure gauges at temperatures exceeding 65 C 150 F It is recommended to use a trap in cases where the pressure gauge is used with steam or liquid media at high temperatures A trap or similar device should always be fitted near the instrument and filled with condensed fluid before pressurising the system so as to prevent the hot fluid from reach
14. ure connection and the other on the instrument s process connection If the pressure connection has a tapered thread the seal is achieved by simply screwing the connection onto the coupling through the mating of the threads It is common practice to wrap PTFE tape around the male thread before coupling see Fig2 In both cases the torque must be applied using two hexagonal spanners one on the flat faces of the instrument process coupling and the other on the pressure connection Do not use the case as a means of tightening as this may cause damage to the instrument When pressurising the system for the first time check the tightness of the connection seal All instruments must be mounted in such a way that the dial is vertical unless otherwise indicated on the dial itself When the instrument includes a safety device this must be at least 20 mm from any other object For wall or panel mount instruments make sure that the pipe conveying the pressurised fluid is connected to the instrument coupling without exerting torsion or force E727 Effect of liquid columns The installer must be aware that if the instrument is subjected to the load of a liquid column it must be calibrated to compensate for this effect In this case the compensation needs to be indicated on the dial and should therefore be communicated to LEITENBERGER when placing the order E8 Putting into service The instrument must always be put into service wit
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