Pressure/Differential Pressure Transmitter Selection

• Posted by ARTANG ZHAO May 13, 2025 Filed in Arts & Culture 9 views
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  Pressure transmitters are mainly divided into adiabatic pressure transmitters, gauge pressure transmitters and differential pressure transmitters. Absolute pressure transmitters are used in applications where atmospheric pressure cannot affect the measurement process, such as vacuum distillation columns. Gauge pressure transmitters use atmospheric pressure instead of absolute vacuum, and are used in a wider range of applications. Differential pressure transmitters are used to measure pressure differences.

  Pressure / differential pressure transmitter selection on the issue:

  (1) the measurement range, the required accuracy and the function of measurement: in order to ensure the accuracy of pressure measurement, the minimum pressure measurement value should be higher than 1/3 of the measurement range of the pressure gauge; for the need of long-distance measurements or measurement of the occasions requiring high accuracy, pressure sensors or pressure and differential pressure transmitters should be selected; in the case of measurement accuracy requirements are not high, the choice of resistive or inductive, Hall effect type remote pressure gauge; pneumatic base type Pressure indication regulator is suitable for in situ pressure indication regulation;

  (2) measuring instrument surface to the environment: such as petrochemical industrial environment, the presence of combustible (toxic) and explosive hazardous atmosphere, there are high ambient temperatures, etc.; pressure transmitters, pressure switches should be based on the installation of explosion-proof requirements of reasonable choice.

  (3) The physical and chemical properties and state of the measured medium: such as strong acids, strong alkalis, viscous, easy to solidify and crystallize and gasification and other working conditions;

  (4) Changes in operating conditions: such as changes in medium temperature, pressure, concentration. Sometimes also take into account the parameters from the start to reach normal production, the gas phase and liquid phase concentration and density changes;

  (5) The structure, shape and size of the object container to be measured, equipment accessories inside the container and various import and export material orifices should be considered: such as towers, solution tanks, reactors, boiler steamer, vertical tanks, ball tanks and so on;

  The selection of engineering instruments should be unified: it is required to reduce the variety and specifications as much as possible, and reduce the number of spare parts to facilitate management;

  (7) The actual process situation: it should be considered which type of equipment the object to be measured belongs to. For example, for tanks and cans, the volume of the tank is small, the measurement range will not be too large, and the volume of the can is large, so the measurement range may be larger;

  It also depends on the physical and chemical properties and cleanliness of the medium. Conventional differential pressure transmitters and float-type liquid level transmitters are preferred, and the material of the part in contact with the medium must also be selected; and for some suspended matter, foam and other media, single flange differential pressure transmitters can be used. Some media that are easy to precipitate and crystallize can use inserted double flange differential pressure transmitters;

  (9) For the liquid level of some high-viscosity media and the liquid level of high-pressure equipment, since the equipment cannot be opened, a radioactive level meter can be used for measurement.

  Smart transmitters are already quite popular, and are the most widely used. They are characterized by high precision, large adjustable range, convenient adjustment, and good stability. According to the application conditions, 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 pressure differential pressure transmitter; high temperature/pressure, differential pressure transmitter; corrosion-resistant/pressure, differential pressure transmitter; easy to crystallize/pressure, differential pressure transmitter.