Liquid Filling of Pressure Gauges

Liquid Filled Pressure Gauge
Why Liquid Fill?

  • The liquid fill dampens vibration, mechanical shock, and pressure pulsations, enabling easier pressure readings.
  • The liquid fill eliminates corrosion, moisture penetration and icing due to the ambient atmosphere.
  • The liquid fill lubricates all moving components, dramatically reducing wear of the movement.

How do I choose the right liquid for a filled gauge?
The type of liquid used to fill the gauge varies with the application. Although pure glycerin provides the best performance in most applications, each has its own requirements. For instance, if extreme temperature fluctuations are expected, use silicone oils. Guidelines to help ensure that a fluid is properly matched to an application are:

  • GLYCERIN, 99.5% Pure = 35°F to 150°F
  • SILICONE, 200 centistoke = -100°F to 150°F
  • MINERAL OIL = 0°F to 115°F

What if my applications encounter severe pressure fluctuation or pulsation?
In applications involving severe pressure fluctuation or pulsation, the use of restrictors and/or snubbers is recommended. In addition, liquid-filled gauges increase the service life of gauges in these conditions.

How do I liquid-fill a gauge?
To fill most AMETEK gauges, simply remove the fill plug located on the top (12 o’clock position) of the gauge and slowly pour in the fill media. Be sure to leave an air space between the fill fluid and the top of the window of ½”.

When is liquid-filled gauge case venting necessary?
ALWAYS! * All liquid filled pressure gauges should be vented after the gauge is installed to preserve the accuracy. Temperature fluctuations during shipment and in the process application cause the liquid filling to expand and contract which, in turn, increases or decreased case pressure. As a result, accuracy can be decreased and the pointer may not return to zero properly until the gauge is vented to the atmosphere.

How do I vent my liquid filled gauge?
Simply cut off the rubber tip from the fill plug located on the top (12 o’clock position) of the pressure gauge.*

Does AMETEK/U.S. Gauge sell fill fluids?
No, however, fill fluids are readily available at most Industrial supply companies.


* Model 1900 liquid filled pressure gauges use a pressure equalizing diaphragm and do not need to be vented.