I am working on an oil project and I am preparing some datasheets. I want to know differences beween vent and drain (if any) in instruments such as gauges?
Kind answers is appreciated.
Well, you vent trapped air/gases and you drain trapped liquids (depending on applications).
For example consider dP transmitter/gages--
for liquid applications, there is a vent screw/hole somewhere in the sensor body that may be used to release the trapped air/gases at the diaphragms of the sensor.
For gas applications, there is a drain screw/hole somewhere in the sensor body that may be used to release the trapped liquids/condensates at the diaphragm of the sensor.
Why do you want to vent and/or drain? Because the trapped gases or liquids may introduce errors in the sensor readings.
Vent is generally for removal of air bubbles & Non condensable gases & drain to remove condensates like in pneumatic air.