The measuring system is essential for pressure gauging. Correct selection and verification (calibration) of the pressure gauge are very important for accurate measurement. Besides, correct installation of the whole system is also essential. If only the pressure gauge is accurate, its results cannot completely represent the actual parameters of the measured medium, because the error of the measuring system is not equal to the error of the pressure gauge. The correct installation of the pressure gauge system includes the position of the pressure tap, the reasonable laying of the connecting pipe and the correct installation position of the pressure gauge.
1. Selection of the position of the pressure tap
(1) Avoid areas where pipes are bent, bifurcated and flow streams form vortices.
(2) When there are protruding objects (such as temperature measuring elements) in the pipeline, the pressure tap should be installed in front of them.
(3) When the pressure tap is required to be near the regulating valve, the distance between the pressure tap and the regulating valve should not be less than 2 times the pipe diameter if the pressure tap is in front. If the pressure tap is behind it, the distance should not be less than 3 times the pipe diameter.
(4) For a wide container, the pressure tap should be installed in an area where the fluid flows smoothly with no vortex. In short, the position of the pressure tap should be able to ensure the required process parameters.
2. Laying of connecting conduits
The horizontal section of the connecting conduit should have a certain slope to eliminate condensed liquid or gas.
(1) When the medium to be measured is gas, the conduit should be inclined towards the pressure tap.
(2) When the medium is liquid, the conduit should be inclined towards the pressure gauge.
(3) When the measured parameter is a small number of differential pressure, the inclination can be slightly larger.
The different types pressure measuring instruments should be installed perpendicularly to the horizontal plane. It should face a proper direction for the convenience of operation and observation. The end of the pressure source component should not exceed the inner wall of the equipment or pipeline. On the same pipeline, the pressure gauge should be in front and the temperature gauge should be in the back. The distance between them should be greater than or equal to 200mm.