I have a doubt about the reading in Glycerine fillled hydraulic pressure gauges (0 to 350 Bar).

Sometimes during checking the hydraulic system pressure, the pressure gauge fluctuates about 10 to 20 bar. Is it common in pressure gauges. Any body can explain about this.

Another doubt that: consider a pressure gauge (Glycerine filled) range is 0 to 350 bar. If the pressure goes above 350 bar then what will happen? the gauge gets break? similary if the pressure goes below 0 bar then waht will be the effect on pressure gauge?

As per my knowledge a lot of people are using pressure gauges but only few persons only knows the solution for this!

Your guage is indicating what your hydraulic system is doing,can you really see 10 or 20 bar on a gauge that reads 350? If you exceed rated guage pressure then your gauge can no longer be determined as accurate unless it is checked/tested against a master gauge.Pressure gauges arent designed to read vacuum or negative pressures so my guess is that nothing? will happen.I have never applied a positive pressure gauge to a negative system

quote:

Originally posted by Sundar:
I have a doubt about the reading in Glycerine fillled hydraulic pressure gauges (0 to 350 Bar).

Sometimes during checking the hydraulic system pressure, the pressure gauge fluctuates about 10 to 20 bar. Is it common in pressure gauges. Any body can explain about this.

Another doubt that: consider a pressure gauge (Glycerine filled) range is 0 to 350 bar. If the pressure goes above 350 bar then what will happen? the gauge gets break? similary if the pressure goes below 0 bar then waht will be the effect on pressure gauge?

As per my knowledge a lot of people are using pressure gauges but only few persons only knows the solution for this!

We are talking about a Bourdon style manometer....
I have damaged a few of them over the years and it has allways been by over pressure....me experience is that they start take damage when the "needle" have turned 360 deg and hit the "stop pin" from behind.....that means you over pressure by about 30%....I have overpressureized 10-25% without damage....BUT I dont recommend it.....I think it is the tube coil inside that can get permanent damage....get a little un-coiled.....

I can understand what you say about the fluctuating....I have never had that problem with a liquid filled gauge....if you are sure that pressure is not fluctuating, then you must have a poor quality or a damaged gauge...

About under-pressurizing...It depends on the range on the gauge....Vacuum is about 1 bar.....1 bar under pressure on a 350 bar gauge wont do damage.... but 1 bar under pressure on a 3bar gauge....would most likely do damage....

WHAT IS "QUALITY" ON A GAUGE??
Accuracy??
Precision??
Linearity??
Read-ability??
Allways show the "same", for the "same" pressure??
Price??
Live up to expectations??