This post tries to describe the use of diaphragm seal since the standard installation of pressure instrument is by using pressure transmitter which is remotely mounted from process taps and connected by impulse line which is commonly a tubing. In some installation, standard installation using tubing is not suitable for the system thus require diaphragm seal in lieu of tubing impulse line.
Compare to tubing impulse line, diaphragm seal costs more thus the use of diaphragm seal must be justified by its functionality against the process requirement where impulse line becomes limitation.
Diaphragm seal provide the following benefits:
- Prevent the process fluid getting clogged in the impulse line due to temperature change that may affect the properties of the process fluid.
- Prevent corrosive fluid contacting with the pressure sensor.
- Prevent slurry or viscous fluid entering the impulse line and the sensor which may be plugging inside.
- In level measurement, the use of diaphragm seal may be placed in lieu of wet leg arrangement which require more maintenance on service where the process fluid inside the wet leg is not stable hence eliminate the needs of refilling.
- For high temperature service, diaphragm seal may reduce more process temperature compare to the use impulse line, hence the transmitter is not exposed to the temperature which above its operating limit.
Hence diaphragm seal should be the choice when it is expected to encounter as such condition.