When measuring operating pressure with pressure transmitter or gauge on common systems industrial processes such as pipelines, pumps, tanks, compressors and etc, unexpected faulty reading might appear if the instrument is not installed properly. Improper mounting position of the instrument is likely to cause deviated and unstable reading. For example, when a pressure measuring instrument monitors a process system, its actual object of measurement is usually the static pressure of the medium. However, additional dynamic pressure would be generated by the flow of medium with velocity and mistakenly detected by the sensor at improper place, overstating the output. Figuring out and preventing typical cases of mistaken installation contribute to obviating abnormal instrument output and reading discrepancies.
Instrument Height
The height of instrument mounting location should not be significantly far from the process. If a liquid measuring transmitter is mounted far blow the process pressure port, the sensing diaphragm would have to bear extra hydrostatic pressure of medium filled in the long impulse line caused by increased height different without pertinent calibration. While when the transmitter is much higher than pressure port and medium is steam, the medium inside impulse line at ambient temperature could partially condense, causing inaccurate reading. If remote capillary connection have to be applied due to constraint of on-site operating condition, it should also be noticed to minimize capillary length and mounting height difference as possible.
Pipeline Elbow
For pipeline application, it is not advised to install pressure measuring instrument at the corner in any circumstance. Sensing element at pipe elbow would inevitably affected by flow monument of the medium, unnecessarily detecting extra dynamic pressure. Therefore a transmitter mounted on pipeline elbow could overstate the pressure reading comparing to the one mounted on straight section upstream or downstream of the same pipeline.
Fluid Momentum
As mentioned above, accurate static pressure measurement is not likely to be ensured if dynamic pressure impacts the sensing element. To minimize the effect of it, the pressure sensing point should be located at the place where medium flow inside the process is developed fully, which in simple terms means the flow has traveled a length of straight pie and merely static pressure is exerted on the wall. Therefore the mounting position of the instrument should keep reasonable distance, relating to diameter of the process, from inlet nozzle, elbow corner, reducer, control valve and other components that change medium momentum.
Blockage in the process
Pressure measurement might not be easy for medium that is highly vicious and likely to clog inside the wetted-part of instrument. The deposit could cause the element sense completely incorrect pressure value. In this kind of application, it is recommended to install pressure transmitter with non-cavity flat diaphragm structure as process connection to eliminate nooks and crannies easy to clog and regularly flush and clean process system interior.
Appropriate installation is the basic to ensure the pressure measuring instrument to function properly and avoid abnormal and unstable pressure readings. Shanghai Wangyuan has been engaged in the field of measurement instrument manufacture for over 20 years. If you have any demands or encounter issues on pressure measurement please feel free to contact us.
Post time: Nov-18-2024