Selection of Differential Pressure/Pressure Transmitter

• Posted by ARTANG ZHAO May 12, 2025 Filed in Arts & Culture 95 views
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  Intelligent transmitters have become quite popular and have the widest and most common applications, which are characterized by high accuracy, large adjustable range, and very easy adjustment and good stability. Among the various types of instruments, transmitters are roughly divided into pressure transmitters and differential pressure transmitters. Transmitters are commonly used to measure pressure, differential pressure, vacuum, liquid level, flow and density.

  According to the application of the main types of transmitters are as follows: low (micro) pressure / low differential pressure transmitter; medium pressure / medium differential pressure transmitter; high pressure / high differential pressure transmitter; absolute pressure / vacuum / negative differential pressure transmitter; high temperature / pressure, differential pressure transmitter; corrosion resistance / pressure, differential pressure transmitter; easy to crystallize / pressure, differential pressure transmitter.

   

  Differential pressure transmitter in addition to measuring the differential pressure value of the two measured pressures, it can also be used with a variety of other throttling instrumentation to measure the flow rate, can be directly measured by the level of the pressurized container and atmospheric pressure container level as well as pressure and negative pressure.

  Selection of Pressure/Differential Pressure Transmitter

  The selection of pressure and differential pressure transmitters is usually based on installation conditions, environmental conditions, instrument performance, economy and application media and other aspects of comprehensive consideration. Practical applications can be divided into direct measurement and indirect measurement; its use in process measurement, process control and device interlock. Common pressure and differential pressure transmitters are common pressure transmitter, differential pressure transmitter, single flange transmitter, double flange transmitter, inserted flange transmitter and so on.

  (1) to the nature of the measured medium indicators for the benchmark, in order to save money, easy to install and maintain for reference. If the measured medium is high viscosity and easy to crystallize strong corrosion occasions, it must be selected isolation type transmitter.

  (2) in the selection should also take into account the measured material medium on the corrosive effect of the membrane box metal, we must choose a good membrane box material, otherwise the use of a short time after the outer diaphragm corrosion damage, the flange will also be corroded and damaged resulting in accidents caused by the equipment and people, so the pressure and the choice of the membrane box material of the pressure transmitter is particularly important. Transmitter diaphragm box material has ordinary stainless steel, 304 stainless steel, 316L stainless steel, tantalum diaphragm box material.

  (3) in the selection should also take into account the temperature of the measured medium, if the temperature of the material medium is as high as 200 ° C ~ 400 ° C, it is necessary to use high-temperature type pressure and differential pressure transmitter, otherwise the transmitter in the silicone oil will be vaporized and expanded, so that the measurement is inaccurate.

  (4) in the selection of equipment also takes into account the working pressure level, pressure and differential pressure transmitter pressure level must be consistent with the application. From an economic point of view, the outer membrane box and insertion part of the material is more appropriate, but the connection flange can be selected carbon steel, chrome-plated, which will save a lot of money. Isolated pressure transmitter selection is best to choose the form of threaded connection, which saves money and easy to install.

  (5) for ordinary pressure and differential pressure transmitter selection, but also to consider the corrosive properties of the measured medium, but the use of the medium temperature can be disregarded, because the ordinary type of pressure change is induced to the table, the long-term operating temperature for room temperature, but the ordinary use of the maintenance of the type than the isolation type of large. First of all is the heat preservation problem, in the northern winter temperature reaches below zero, will make the pressure guide tube icing, resulting in the transmitter can not work or even damage, which need to increase the accompanying heat and heat preservation and other measures.

  from the economic point of view, the selection of transmitters, as long as the medium is not easy to crystallize can be used ordinary transmitters, and for low-pressure crystallization medium can also be added to the blowing medium to indirectly measure (as long as the process allows the use of blowing liquid or gas), the application of ordinary transmitters is to require maintenance personnel to carry out more regular inspections, including a variety of leakage of the conduit, whether or not the blowing medium is normal, whether or not the insulation is good etc.