brnt999
Contributor
A few people have told me to turn the face of the spg away when turning on the air because the glass could blow up in my face. Its not something I recall being taught by Padi. Is there truth to this?
Bursting SPG
- Thread starter brnt999
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victorzamora
Contributor
It's something I do every time. I think it's a relic of days gone by, but SPGs have to deal with 3000+ PSI and they get hit by it pretty abruptly. It definitely CAN'T hurt to practice it that way.
Peter_C
Contributor
I was taught not to look at not stand in front of my welding gas gauges when turning the tanks on. *shrugs* it is ingrained into me for all gauges.
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I've heard it rarely happens, but a slight crack could be the cause. I was taught in Rescue course to also keep your finger on the 2nd stage purge button when you turn air on, then release it quickly (so as not to waste air). This gives the air somewhere to escape other than it all going right to the SPG.
Bob DBF
Contributor
Back in the day there was not a blowout plug on SPG's and a number of them blew the face off the gauge when the bourdon tube cracked and let HP air into the case. Haven't heard of it happening in a long time.
That being said, I am carefull with HP and pressurise slowly and I don't directly face anything I am pressurizing to HP because if anything does go wrong...
Bob
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I may be old, but I'm not dead yet
That being said, I am carefull with HP and pressurise slowly and I don't directly face anything I am pressurizing to HP because if anything does go wrong...
Bob
---------------
I may be old, but I'm not dead yet
We always teach it in class. One of our DMs was demoing it when his SPG face went across the pool- best demo we ever had 
... I have had one turn loose at the bench and go across the room. It's not common but it does happen and well worth turning the gauge away just in case.
... I have had one turn loose at the bench and go across the room. It's not common but it does happen and well worth turning the gauge away just in case.
Maybe this will help. The vast majority of Bourdon Tubes consist of a slightly flattened copper alloy tube that is bent into a “C”. Every time it is pressurized, it flexes by straightening out a little. That movement is amplified by gears connecting the needle. Metal “work hardens” under these conditions and eventually fails by cracking. When, not if, it does gas leaks into the gauge housing — sometimes pretty fast.
Are Bourdon tubes in SPGs reliable? Very. Are the more reliable than they used to be? Not really, but they are much safer. The reason is all come with a blow-out plug now that pops out before the glass face blows into yours. So now the question is: Would you bet your eyesight on that working EVERY time? Your bet, your choice.
Pressure measurement - Wikipedia, the free encyclopedia
Are Bourdon tubes in SPGs reliable? Very. Are the more reliable than they used to be? Not really, but they are much safer. The reason is all come with a blow-out plug now that pops out before the glass face blows into yours. So now the question is: Would you bet your eyesight on that working EVERY time? Your bet, your choice.
Pressure measurement - Wikipedia, the free encyclopedia
kwinter
Contributor
Here's my handgun. You watched as I removed all the bullets. Now point it at your face and pull the trigger.
SPG blow up? No way. Can't happen. But why take the chance on the impossible? Yes, I make sure it is turned away from me when I open valves, and I do it slowly.
SPG blow up? No way. Can't happen. But why take the chance on the impossible? Yes, I make sure it is turned away from me when I open valves, and I do it slowly.
AfterDark
Contributor
We were taught to do the same thing back in the 60's. Been doing it since then, never had a SPG blow in all that time. It's been just a habit for a long time.
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