Compensated Subsea Pressure Gauge - 63mm Bottom Entry Stainless Steel Case

63mm diameter compensated subsea gauge with rear compensating diaphragm to all process pressure to be measured against the ambient sea water pressure subsea. 

Conventional subsea pressure gauges rely on the strength of the case and window to withstand the external pressure of the water in much the same way as a submarine.

The Ashford Instrumentation range of compensated subsea pressure gauges work on a different principle which negates the necessity of having an expensive reinforced case although there are some limits on the applications this design can be used on.

The compensated subsea gauge features a liquid filled case that has a special device that allows the internal of the case to be pressurised equal to the increase in ambient of the water as the gauge is submerged. The benefit of this method is that as the internal and external pressure remains in balance there is no need for a pressure proof case and window to be fitted and in theory there is no limit to which this gauge can be submerged.

 There are however application limitations on using this design of gauge. A conventional subsea gauge will compare the subsea reading to atmospheric or gauge pressure at the surface (i.e. the zero point equals 1 atmosphere or approximately 1 bar absolute). However the compensated gauge will compare the subsea reading with the local ambient pressure at depth with the zero point being equal to the ambient pressure. Provided the system being measured is also effected by this increase in ambient pressure then the gauge reading will be correct. If however the pressure system is not effected by the increase in ambient pressure (such as in the case of a gas cylinder) the gauge will start to read increasing low as the depth increases.

Whilst this error may be small at shallow depths especially on a gauge with a high pressure range, on a low pressure range at deeper depths this could be a significant issue. For example: 100m depth would give an error of around 10 bar, a 1000m depth would give an error of around 100 bar.

If you have any doubts over the suitability of this design for your application please do not hesitate to contact our sales specialists on 0044 (0)1233 730999. Please note this 63mm compensated gauge is only available in direct mount bottom entry design.