A pigtail siphon can be used to help dissipate heat between a hydraulic system and the gauge â provided ambient temperature is low enough.
Vibration from pumps, motors, and other rotating equipment can accelerate wear and premature failure of internal working parts of a pressure gauge, especially the Bourdon tube and the gear and movement mechanism. Vibration can also cause pointer oscillation, which makes it difficult to obtain an accurate reading. One of the most common causes of pressure gauge failure is exposure to continuous vibration.
The most widely accepted remedy is to utilize a liquid-filled pressure gauge. The fill fluid of choice is either glycerine or silicone. Liquid-filled gauges address not only pointer oscillation, but also serve to protect and lubricate the internal geared movement.
Pulsation influence
Process pulsation can occur around the discharge of pumps as well as quick operating valves. Many users assume that liquid filling a pressure gauge will fully address pulsation. Although a liquid-filled gauge helps damp the effects of pulsation, it often does not fully address this fluid condition. Pulsation dampers are installed upstream of the gauge connection, and they can be a piston-type snubber, a sintered metal snubber, or a threaded in-flow restrictor in the socket of the gauge. A needle valve installed upstream of the gauge that is slightly opened is another common practice to address pulsation.
Noshok does not recommend to rely solely on a needle valve to address pulsation because you could inadvertently open the valve, and thereby negate flow restriction. In clean fluids (gases or clean low viscosity liquids) a threaded orifice (flow restrictor) or a sintered metal snubber is the least costly way to address pulsation. In dirtier and higher viscosity fluids a piston snubber is usually installed.
Summary
Temperature, vibration and pulsation are three process conditions that adversely affect a pressure gauge. Being aware of these three process conditions, and taking the necessary steps to address them, can help minimize accuracy errors and add to the service life of the pressure gauge.
This information was provided by Michael Lancaster, Engineering Manager at Noshok Inc., Berea, Ohio. For more information, call (440) 243-0888.