Air out on a Rental SPG reading 500psi, Advice appreciated...

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Hi All,

New to the forum and need a little advice.

I recently rented a BCD, reg and tank to do a little maintenance on the bottom of my pool. When picking the gear up the equipment was obviously well used (tatty) but as it was only for brief use in the pool no worries, I did think it a little strange that the dive shop didn't ask for any credentials. Hey ho... Upon arrving at home and assembling the gear it was apparent that the inflator or low presure hose connection to the bcd was faulty as I had to jiggle it to get the bcd to inflate..... again no issue as im only in the pool (max depth 8ft) I proceeded to clean a few hard to get to areas for the next hour and a half with a few coffee breaks... The tank was now down to just over 50bar / 750psi and I was getting close to wrapping up the job in the shallow end in no more than 5ft of water at this point breathing became noticably harder and having done out of air drills i knew the tank was close to out despite the SPG reading 40-50 bar / 6-700psi. Hmmm... at this point i was mainly annoyed at not being able to wrap up the job but then started to mull the safety implications....

I returned the gear to the shop and told them about the BCD issue and to make sure there were no misunderstandings (In Spain and my spainish is limited) i kept the rig assembled so they could see the SPG reading and show that there was no gas depite reading 500psi... The shop basically told me regarding the low pressure hose that i should have tested the gear before leaving the shop... well ok... on the subject of the tank running dry with 400psi on the SPG they were more cagey and said i must not have opened the tank valve fully... well im trained to and always open my valves 100% every time so this was clearly not and issue and from my understanding would not have lead to a dry tank with a 400psi reading on the SPG. They basically washed their hands of me so I left a negative review of the facility online.

Later that the day in response to my feedback they start to accuse me of damaging their equipment, flooding the tank and regulator and that due to the water ingress the SPG malfunctioned and therefore showed positive pressure.... correct me if im wrong but the likleyhood of water ingress through the reg in 5ft of water is low to zero with (3-400psi) in the tank and the likelyhood of that water getting to the SPG is also very low to nil. While at the dive shop I did manage to pull a labored breath through the reg so there was a little gas left in the tank just very hard to pull...

Just want to sanity check my reasoning as I feel they are trying to flip the blame onto me for badly maintained and down right dangerous rental gear. Any feedback is much appreciated.
 

wnissen

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2 meters of water is .2 bar or 3 psi, so I agree that it seems unlikely that you could have introduced water by flooding a pressurized reg. Stuff happens, I'm not saying it's impossible, a piece of dust could have been in the opening when you assembled it and got stuck in the SPG. SPGs do fail, that's why I always watch mine when opening the valve, taking a couple test breaths, and again after de-pressurizing. My guess is you didn't break anything, but how can you prove it? Might be better off just buying a new one as the price of ending this dispute.

The thing that worries me (more than you getting ripped off) is there might be water in the tank or reg. Did you check? I'd want a VIP refilling a truly empty tank anyway.
 

BlueTrin

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2 meters of water is .2 bar or 3 psi, so I agree that it seems unlikely that you could have introduced water by flooding a pressurized reg. Stuff happens, I'm not saying it's impossible, a piece of dust could have been in the opening when you assembled it and got stuck in the SPG. SPGs do fail, that's why I always watch mine when opening the valve, taking a couple test breaths, and again after de-pressurizing. My guess is you didn't break anything, but how can you prove it? Might be better off just buying a new one as the price of ending this dispute.

The thing that worries me (more than you getting ripped off) is there might be water in the tank or reg. Did you check? I'd want a VIP refilling a truly empty tank anyway.
It’s the shop tanks and regs, they should service it after this incident, if they really believe that there was some water ingress.
 

John C. Ratliff

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I think the SPG is damaged, probably by putting it on a tank with too high a pressure. This or damage by having it hit hard on something is about the only way of making those gauges read more than zero when there is nothing in the tank. It is pretty obvious to me that the dive shop doesn’t know what they are doing, and I’d steer away from them in the future.

Now about introducing water into the tank, if you did not take the regulator off the tank while it was underwater, it is almost not possible. To get a negative pressure inside the tank, you’d need a warm tank on a hot day introduced to cool or cold water with the valve open. That would do it.

I dove an old U.S. Divers Company SPG last week with a malfunction in the O-ring on the outside of the gauge. It was a river dive, so in freshwater, and water clearly entered the gauge. But it did not enter the Bourdon tube, as that is isolated, and it functioned normally. In order for water to enter the gauge from the inside, it would have to travel from the second stage to the first stage, flood the first stage, then somehow get into the HP line through that tiny hole, and get up to the Bourdon tube, where it would need to evaporate and deposite salt inside the tube. From your description of your dives in a freshwater pool, that would simply be impossible.

‘Hope this helps.

SeaRat

PS, here’s a discussion on how a Bourdon tube pressure gauge works.
Bourdon Tube-Working,Construction,Types-C-type,Helix,Spiral
 
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Thanks for the feedback, pretty much confirmed my initial thoughts. Cheers!!
 

BlueTrin

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Out of curiosity, in a SPG with a swivel, my understanding is that the swivel itself is not water tight because it has no o-rings. The o-rings are on the swivel bar .

So water will enter and touch the middle of the swivel bar but will not enter the part of the SPG after the swivel bar.

Does that mean that I should detach the SPG from the hose and clean from time to time this area to prevent a build up ?
 

AfterDark

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Out of curiosity, in a SPG with a swivel, my understanding is that the swivel itself is not water tight because it has no o-rings. The o-rings are on the swivel bar .

So water will enter and touch the middle of the swivel bar but will not enter the part of the SPG after the swivel bar.

Does that mean that I should detach the SPG from the hose and clean from time to time this area to prevent a build up ?

When I service my regs I clean everything including the all hoses at both ends and change the O rings. Even my snap clips get cleaned at that time. So IMO yes from time to time whenever you feel like it but at least at service time. Post dive rinse of my regs is done using warm water whenever possible, the set soaks in it until it cools off. Then gets a quick warm water spray. The warm water dissolves the salt and the spray washes it away.

OP if you ever use that LDS again IMO you should do just what they said you should have done and assembly everything at the store, and have someone video you doing it.
 

John C. Ratliff

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I'm not so much disassembling these SPGs, but I dive almost exclusively in fresh water. I agree with AfterDark, if you dive salt water, do as he does.

SeaRat
 
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