Selecting Pressure Gauges: Criteria to Consider?

A principal concern is the compatibility between the fluids at the temperatures and pressures, and the wetted materials. It would be no good, for example, fitting a bronze gauge to a line containing hot sulphuric acid.

Many organisations have Standards to be followed. Pharmaceutical primary manufacture, for example, might specify diaphragm gauges on all primary bulk manufacturing lines. Steam is never attached to a diaphragm gauge, and the gauge is nearly always attached to a line via a 'pigtail' condensate loop and a gauge isolating cock. Gauges attached to the outlet of centrifugal pumps will normally have a 'snubber', a device that minimises and smooths-out the effects of vibration caused by turbulence generated by the pump. Others might insist on glycerine-filled gauges. Some applications might insist on blow-outs on the back off the gauge so the case doesn't rupture catastrophically if the sensing element leaks.

Check the organisation's local instrumentation standards and follow them. They will have been developed on the basis of best local practice. If these don't exist or are unclear, then copy similar installations that work, having first discussed the pros and cons with the local Maintenance Technician in each case so that pitfalls can be avoided.