When a gauge suffers from the effects of vibration or pulsations, the pointer vibrates very rapidly making it very difficult to make accurate stable readings. The main cause of this effect is installing a gauge close to a pump or any process that vibrates in normal operating conditions.

The key reason for fitting either a viscous damped Movement (VDM) or filling a case with glycerine is to overcome the effects of vibration and pulsation. It must be stated, however, that it does NOT replace a check screw or a pressure snubber for major pressure fluctuations or vibrations that are continuous and problematic, both of which can be supplied fitted into the inlet of the gauge.