Using a screw in or waterproof pressure transmitter to measure liquid level

8th November 2007
The first step in selecting a pressure transmitter for liquid level measurement is too determine whether to measure it by immersing the pressure transmitter or by mounting it externally to an outlet pipe or the wall of a storage tank.

Mounting a liquid level pressure transmitter externally is nearly always preferable because a screw in pressure transmitter is relatively cheaper than one that is immersed and it is also easier to service. 

If you are mounting a liquid level pressure transmitter externally, care should be taken not to install it onto pipes where there is likely to be a high flow of liquid or pump pressures since these may interfere with the hydrostatic pressure reading.

Water proof pressure transmitters are used when it is not possible to provide access from the outside at the point you would like to measure the liquid level.  For example there is no way to fit a pressure transmitter to the outside of a buried water storage tank without excavating the ground around it, so a waterproof pressure transmitter is the most economical solution.
 
Normally a manufacturer will clearly describe in the specification whether a pressure transmitter has an immersion option. In Europe there is a system for rating the level of water tightness which is the Ingress Protection Rating or more commonly known as the IP Rating. For immersion the pressure transmitter should be sealed to a rating of IP68.  If it is not clearly marked in the literature you should clarify with the manufacturer for what depth and duration it can be submerged, e.g. IP68 to 60 mH2O for 24 hours which is intended for installation in a flood risk area, would not be suitable for a permanently installation.


Related Products

Screw-in hydrostatic level transmitters for tank contents measurement

Submersible liquid level transmitters for underground tanks, boreholes and reservoirs

Accessories for installing liquid level transmitters

Digital panel indicators for displaying liquid level


Associated Topics

Low pressure level transmitter for shallow water depth measurement

Logger for corrosive liquid media

Screw-in level transmitter for liquid chemicals

Marine approved level transmitter for cargo, fuel, ballast and waste storage tank

PVC submersible level transmitters for liquid chemicals

Protecting submersible sensors from internal condensation damage

Converting hydrostatic level into pressure

Measuring fluid level in a sealed tank


Site Last Updated:  09/02/12

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IP Ratings Explained

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