Meet new scuba divers, maintain a virtual dive log, participate in our forum, share underwater photos, research dive sites and more. Members login here.

Poll - SPG (Submersible Pressure Gauge) blow out
PhilB - 5/03/2016 2:09 PM
Category: Equipment
Replies: 12

Just a poll please.

1. Has anyone seen first hand an SPG blow out the glass cover when initially pressurizing the system? Some agencies teach to point the gage glass away from human faces until after you pressurize the system and check for leaks.

2. Has anyone seen a blow-out plug on the back of the gage housing which would make this practice even more dangerous? One Australian site referenced such a device.
LatitudeAdjustment - 5/03/2016 5:50 PM
I saw an instructor telling a student that and wondered the same thing.

I’ve been diving off and on since 1962 and have no 1st, 2nd or 3rd hand knowledge of this ever happening, not even on a dive trip with alcohol involved. Burst disc and o-rings yes! Underwater ghost stories, yes. No exploding SPD from either end!
danbowkley - 5/03/2016 10:26 PM
Same here. I did watch a youtube vid recently in which an instructor I’d call reputable basically said that very old SPGs had this problem but that anything even remotely recent (with the blowout plug on the back) would fail via that route. Personally I just let it hang down and stabilize before I pick it up, either way nothing would be headed for my face.
PhilB - 5/04/2016 8:51 AM
Resqdivemedic - 5/04/2016 11:02 AM
I just finished my Divemaster class and they wanted us to face the SPG inward inside the BCD when pressurizing the reg. I was told it was done because if there is a failure of the SPG/Console it would contain the blast. Never questioned it but now this topic came up it has ne thinking about it. This goes along with the videos I’ve seen of the skill as well.
PhilB - 5/04/2016 11:20 AM
Thanks Bob. I have seen a lot of recent chatter regarding the peanut gages especially on pony bottles and rebreather equipment having problems but not so much on the regular console sized gages shattering or even failing.
Sonnylynnvick75 - 5/04/2016 4:20 PM
The only problem I’ve had was the burst disc leaking on my SPG and I had to replace the entire gauge, no big deal. I just always let it hang to the side so theres no worry either way.
PhilB - 5/04/2016 4:41 PM
Thanks Sonny.
Resqdivemedic - 5/04/2016 5:50 PM
Did some research and found it has happened but it was with older SPGs. Another point of failure is the connection between the SPG and hose, if its not tight it can separate. No shrapnel causing injury but it has happened during a dive. They lost the console but were able to surface with enough air.
M-i-k-e - 5/04/2016 6:24 PM
I bought an TUSA SPG from leisurepro a few years ago. Fortunately I had the good sense to put it it a trash barrel full of water the first time I pressurized it. It basically blew up into a couple dozen pieces! So i dont think it would have made much of a difference which way I faced it!
John_giu - 5/26/2016 10:43 PM
No, but I do purge my second stage as I open the tank valve. Both probably urban legend.
Actually I have a habit of watching the gauge to check tank pressure.
Still better the getting hit in the eye with glass.
Diver_Diva - 5/26/2016 11:36 PM
Wow - this is the first time I have ever heard of that happening.

I bought a new SPG about a year ago because the glass on the old one was so scratched up I could barely read it. But I never had a problem with either one of them.
TLC - 11/04/2016 12:22 PM
In the link given by Phil, the SPG at the bottom shows a safety relief - a orange O’ring in this example. If you were to dig out that O’ring on that model it just has a series of small holes to vent off any excess gas in the unlikely event the mechanism fails. Opening your cylinder slowly would be wise option, and the hose is more likely to fail than the SPG.

The main face of an SPG is not pressurised. If the SPG has a vent, it will not come out like a bullet - that wouldn’t be an improvement in safety would it? You should keep your hand clear of the back, and in some case the top of the SPG, although the SPG will typically be in a housing.