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dang it... pressure gauge question

Posted: Mon Aug 25, 2008 11:34 am
by SilentCyan
well i epoxied my pressure gauge into my cannon yesterday and a few hours later noticed that there was a little sticker on the side saying not for compressed air. is this the same kind of deal like with pvc pipe or do i need to rip it out and get a new one?

and what the heck is lowes doing putting those things beside their air compressors anyways?

Posted: Mon Aug 25, 2008 11:48 am
by starman
Are you sure it didn't say "not for Oxygen or O2"? Big difference from compressed air. I don't think I've ever seen a gauge that said that. And are sure the sticker wasn't related to some PVC part or pipe you purchased? That is commonly stated for PVC.

Also, you shouldn't need to epoxy your gauge in. Get yourself a 1/4" NPT tap and 7/16" drill bit and tap your own threaded holes. Do it in a location where there is a double layer of PVC such as where a coupler has been cemented to the pipe. Use a couple of layers of teflon tape around the gauge threads and you'll be good to go.

Posted: Mon Aug 25, 2008 12:18 pm
by daxspudder
starman wrote:Are you sure it didn't say "not for Oxygen or O2"? Big difference from compressed air. I don't think I've ever seen a gauge that said that. And are sure the sticker wasn't related to some PVC part or pipe you purchased? That is commonly stated for PVC.

Also, you shouldn't need to epoxy your gauge in. Get yourself a 1/4" NPT tap and 7/16" drill bit and tap your own threaded holes. Do it in a location where there is a double layer of PVC such as where a coupler has been cemented to the pipe. Use a couple of layers of teflon tape around the gauge threads and you'll be good to go.
He meant 3/16"

Posted: Mon Aug 25, 2008 12:23 pm
by SilentCyan
i just used what i had which was a one half inch drill bit and some epoxy. and the warning sticker is on the side of the gauge. what i meant was is the warning about using compressed air their because something could explosively break or it just won't work?.

the warning might have said Oxygen but i can't really remember. i'll have to check it when i get home. in the meantime, and please excuse me for being new at this, why does it matter whether its oxygen or compressed air?

Posted: Mon Aug 25, 2008 12:37 pm
by ShowNoMercy
02 tends to be explosive.

Posted: Mon Aug 25, 2008 12:38 pm
by jonnyboy
Never seen that before. :? Just use it up to the highest reading on the gauge you should be fine.

Posted: Mon Aug 25, 2008 1:10 pm
by starman
daxspudder wrote:He meant 3/16"
No, I meant 7/16". The starter hole for a 1/4" NPT thread is 7/16".
SilentCyan wrote:i just used what i had which was a one half inch drill bit and some epoxy. and the warning sticker is on the side of the gauge.
1/2" is too big...thread it properly as I described. As has been said, O2 can be explosive. They make O2 gauges as well.

Posted: Mon Aug 25, 2008 1:28 pm
by SilentCyan
putting it in there isn't the problem as that has already been done. i was just worried that it might not work properly

Posted: Mon Aug 25, 2008 1:55 pm
by jimmy101
ShowNoMercy wrote:02 tends to be explosive.
Not really.

O<sub>2</sub> plus a bit of oil used to lubricate the inside of the gauge can be explosive, especially at high pressures. O<sub>2</sub> plus a bit of residual flammable gas from the last usage of the gauge can be explosive. O<sub>2</sub> itself is not explosive, otherwise O<sub>2</sub> tanks would be regularly exploding.

Gauges and regulators used for O<sub>2</sub> are (1) oil free, (2) never supposed to be used for anything other than O<sub>2</sub> and (3) are pretty well labeled. Usually they will have a thread significantly different (eg. left handed) than do similar parts designed for other gases.

If you look at an oxy-acetylene (or oxy-propane) torch setup it should be impossible to accidentally screw the oxygen regulator onto the acetylene (or propane) tank. You also can't screw the acetylene (or propane) regulator onto the oxygen tank.

Posted: Mon Aug 25, 2008 2:09 pm
by starman
SilentCyan wrote:putting it in there isn't the problem as that has already been done. i was just worried that it might not work properly
Pressure is pressure. If it's a pressure gauge and you are within its specifications, it will work properly.