View Full Version : Question about Glycerin filled gauges

03-03-2016, 11:47 AM
I have two glycerin filled gauges, one a pressure gauge and one a vacuum gauge, and both are only about half filled due to leakage or spillage. Neither one of the gauges need to be glycerin filled, I donít think, because there is no vibration involved in their application; they just came that way. I want to either fill them up or drain them.

If I drain them: is there a safe solvent to rinse the remaining film off?

If I fill them: is the USP Grade Vegetable Glycerin I use for my E-cigarette juice appropriate?

I would prefer to drain them because that would not involve additional effort and expense.

03-03-2016, 12:47 PM
I drained a glycerin filled fancy-pants tire pressure gage (because the glycerin is absolutely useless in that application and the venting of the housing that was necessary for accurate measurements was a pain in the butt). I just removed the fitting, and held it upside down for a day to drain out. Then I recapped. It's been like that for at least 5 years with no problems, there is still residual glycerin in there but it doesn't seem to care, and neither do I.

03-03-2016, 01:18 PM
The only glycerin filled one I have had the needle rusted off in about six months I no longer use them .

03-03-2016, 01:49 PM
All standard gauges must be vented otherwise simply a change in temperature will expand or contract the air in the gauge and change the reading. I just found two on a jobsite with the vents closed. I opned the vents and the readings changed 20%. Some gauges have just a vent hole, some have a little valve and some have a rubber nipple you clip the end off of.

03-03-2016, 02:32 PM
There's usually a rubber plug TDC, I think the stuff is just damping as you say, does help in corrosive environments, stops the guts going green.

03-03-2016, 03:27 PM
If you empty them, will the loss of damping alter the graduation (accuracy) of the gauge?

03-03-2016, 05:33 PM
I have a glycerin filled oil pressure gauge screwed into the engine block on my ss96" engine (aka Harley engine) for the last 60k miles. Its the only thing that has not vibrated and fallen off.....

03-03-2016, 05:45 PM
I have used drug store mineral oil in the past cheap and easy. Maybe I have been lucky but drained old oil out,partially filled gauge,flipped it around a few times drained out and then re filled with the mineral oil and have had good service.

03-04-2016, 02:30 AM
Replace it with nitroglycerin. That way when the gauge unexpectedly pegs against the end stop, you'll know it!