Liquid filled gauges

[mobilus]

Why are some gauges liquid filled and some not? Is there a rule of thumb as to the choice? And...why the bubble, is it for fluid expansion?

 

[rgr33]

Liquid filled gauges help to buffer the shock from vibrations and operating on rough terrain. I only use glycerin filled gauges on my air blast sprayers for example.
Gauges used on stationary machines, say a well pump, don’t need the shock resistance.

 

[mercdv]

Liquid filled gauges are also used when you need protection against pulsation and pressure spikes. They are used for very high pressure applications. I use them on my high pressure air tanks that hold pressure up to 4500 psi. Forgot to answer the bubble question, it is there to help relieve internal pressures to make sure the gauge shows an accurate reading. If it was completely filled with liquid there would be no room for the liquid to expand and contract with pressure and temperate changes.

 

[WranglerX]

One should also "burp" liquid filled gauge once installed ... Remove rubber plug then just replace it,,,

Dale