What is the fluid in an air compressor gauge?

[toolmiser]

I have an air compressor that has a fluid filled pressure gauge. While doing some repair, I lost some of the fluid. There is a fill plug on the top, so if I knew what the fluid was I could refill it. Could it be something like mineral oil? Obviously its clear but doesn't flow as fast as water, it doesn't have much of a smell.

I appreciate all comments.

Thanks

 

[chris142]

google says this

 

[The Cobbler]

I think they are refered to as "Glycerine filled " but it's really not necessary in a compressor

 

[Sumboodie]

They are cheap.

Had oneblow and shoot all that goop in my face and shirt. and 180* hydraulic oil.

 

[darkzero]

It's glycerine, you can buy a bottle of it at any drug store. It's not required for the gauge to function though, it's purpose is for vibration dampening for the needle etc, like to able read it more accurately when the compressor is running & for gauge longevity. Mine came empty so I filled it, only reason I have the oil filled gauge is cause I got it for cheap on ebay.

Oil filled gauges should not be filled all the way to the top. Even then you should purge the air/vacuum seasonly. I never did this to mine, one day noticed the gauge was not reading correctly & thought it was bad. Purged it (mine has a manual vent but some have a ****** that can be cut to permanently vent) & the gauge started reading fine again.

 

[Rockable]

Glycerine. It just helps damp the oscillations of the bourdon tube and mechanism. Primarily used in hydraulic systems and not necessary for air.

 

[dogdog]

They are cheap.

Had oneblow and shoot all that goop in my face and shirt. and 180* hydraulic oil.

Errrrrrr….. I saw that on the internet

 

[toolmiser]

Thanks for the answer. I think we even have some "in stock" If you add glycerin to soap for making bubbles, it makes the bubble stronger. Something you probably care less about unless you have small kids.

 

[Firebrick43]

 

[dscheidt]

Thanks for the answer. I think we even have some "in stock" If you add glycerin to soap for making bubbles, it makes the bubble stronger. Something you probably care less about unless you have small kids.

J-lube works better. Probably not suitable for use in a pressure gauge though.

(seriously, if you're into big bubbles, it's the bee's knees for making juice for long lasting giant bubbles.)