Environmental seal bulging out

[Jim Lapenta]

That is not that bad but it still needs addressed.
It is either the result of the seal being removed and reinstalled when the reg was not pressurized or depending on when it was serviced last, the diaphragm leaking a bit. If you remove and replace the cap and seal with it pressurized, turn the tank off and purge the reg. It should suck down slightly. When you turn it on again it should come up to level or hair more.
If it bulges like that, the seal needs replaced and a possible rebuild because it's stressed beyond where it was designed to be and you may be getting some air past the diaphragm. Which is not normal.
I wrote the 1st draft of the service procedure for the D3 and D2. I've serviced well over a hundred of them and trained over 50 people to service their own HOG regs before I retired. I know this reg inside and out.

"On the ambient pressure [elevation] note... could this be caused by the reg being assembled/sealed in a chilly environment and the internal air volume expanding that much when reg left in warm sun? Or does the reg always look like this, regardless?"

No, there is not enough air in there to bulge like this. Sitting in the sun should not affect it.

 

[Jim Lapenta]

It's completely normal that the environmental seal bulges out a bit when under pressure.
Where should the air that is compressed by the pressurized main diaphragm go?
For me that bulge on that pic looks normal if the 1st is pressurized.....

I am a retired HOG reg tech instructor and HOG service tech. And I was one of the authors for the service procedure for this one. I wrote the 1st draft and was an editor for the final version. That much bulge is not normal for this reg. Regardless of temperature or altitude.

 

[LordHavoc]

Thanks. I was going to answer Erics question about altitude and that is not a condition for me. That picture is at sea level. Before that Jim Lapenta answered my point. Is this a common problem in all diaphragm regulators or does HOG have this problem more common than other ones?

 

[GF99/99]

That is not that bad but it still needs addressed.
It is either the result of the seal being removed and reinstalled when the reg was not pressurized or depending on when it was serviced last, the diaphragm leaking a bit. If you remove and replace the cap and seal with it pressurized, turn the tank off and purge the reg. It should suck down slightly. When you turn it on again it should come up to level or hair more.
If it bulges like that, the seal needs replaced and a possible rebuild because it's stressed beyond where it was designed to be and you may be getting some air past the diaphragm. Which is not normal.
I wrote the 1st draft of the service procedure for the D3 and D2. I've serviced well over a hundred of them and trained over 50 people to service their own HOG regs before I retired. I know this reg inside and out.

"On the ambient pressure [elevation] note... could this be caused by the reg being assembled/sealed in a chilly environment and the internal air volume expanding that much when reg left in warm sun? Or does the reg always look like this, regardless?"

No, there is not enough air in there to bulge like this. Sitting in the sun should not affect it.

Hi Jim,

Very interesting to hear from a service tech with so much experience. If you don't mind I would love to pick your brain a little more about this subject. I (no formal service tech training but I have service ALOT of regs in the years) always thought this was a somewhat "normal" thing to happen over time. I have about a dozen Apeks DST's and I have noticed when I start getting putting over 250hr on them the 2-3 that I always use on my deep bail outs (+70% Helium content) always bulge out (more than the photo posted) and randomly 1-2 others will have this happening too but just very minimally similar to the photo posted. All I do is unscrew it and I can even hear the pressure release as I'm doing this and then screw it back on.

I see you mentioned the bulging will over stressed the environmental seal. Just out of curiosity what is the potential issue with this or hazard? Is the little rubber/EPDM (or in my case seems like the Apeks ones are some kind of vinyl or PVC type material) cap that sensitive that it can not handle this?

Lastly I know this is not very normal but my theory for my situation is that the high He is just leaking through the diaphragm and if this is the case is this actually a hazard or something of concern. Obviously this leak is so microscopic that it take +250hr just to fill an air space that is about the size of 2 quarters. So would you really classify this as a leak if its that slow? and would you really think it needs a new diaphragm/service?

 

[Jim Lapenta]

Hi Jim,

Very interesting to hear from a service tech with so much experience. If you don't mind I would love to pick your brain a little more about this subject. I (no formal service tech training but I have service ALOT of regs in the years) always thought this was a somewhat "normal" thing to happen over time. I have about a dozen Apeks DST's and I have noticed when I start getting putting over 250hr on them the 2-3 that I always use on my deep bail outs (+70% Helium content) always bulge out (more than the photo posted) and randomly 1-2 others will have this happening too but just very minimally similar to the photo posted. All I do is unscrew it and I can even hear the pressure release as I'm doing this and then screw it back on.

I see you mentioned the bulging will over stressed the environmental seal. Just out of curiosity what is the potential issue with this or hazard? Is the little rubber/EPDM (or in my case seems like the Apeks ones are some kind of vinyl or PVC type material) cap that sensitive that it can not handle this?

Lastly I know this is not very normal but my theory for my situation is that the high He is just leaking through the diaphragm and if this is the case is this actually a hazard or something of concern. Obviously this leak is so microscopic that it take +250hr just to fill an air space that is about the size of 2 quarters. So would you really classify this as a leak if its that slow? and would you really think it needs a new diaphragm/service?

I don't know what Apeks says about their regs but if the diaphragm is installed correctly in a HOG reg and is intact, even with high He mixes I would not expect to see this. The hazard with overstressing the seal is that it is no longer sealing the ambient chamber. And many users will not think to check that and rinse it out. I've seen corrosion bad enough to eat all the chrome plating off of the inside of the chamber because of this issue and the reg saw a lot of use in saltwater.
A late friend sent me this reg that he bought used and wanted me to check it out. What could have been a $50 rebuild turned into a $100 one because the diaphragm clamp had to be replaced. It was so bad that it was pitted to the point where the diaphragm would not seal.
As soon as I got it I threw it on a 6cu ft cylinder with a second stage and dunked it in the sink. Got the bulging disc and champagne bubbles. Then I opened it up and saw the extent of the damage.
Water in the ambient chamber is not really a big deal. Water and crud that doesn't bet rinsed out can turn into a very big deal.
The more you stress the seal beyond what is was designed for, the more you risk screwing up the reg.