HOG 1st Stage Adjustment?

[Peter_C]

Have you tried to purge the last bit into your BC or drysuit? Or breathe the regs down to a light suction? Just throwing ideas out there. We have a set of HOG's and do not have that issue.

 

[blue steal]

Interesting thread. I have the same problem with my HOG 1st stage holding a bit of pressure and blowing off the O-ring. I know the O-ring it is the right size.

 

[JBRES1]

A little off topic, but still related.
I dove on Thursday, removed my reg from the cylinderand put on the bench for a cleaning later.
Today I was cleaning out the reg before putting it away. (no tank attached )
I pressed the purge button on the face of my second, and it gave a burst of air.
So it looks as if the reg can hold on to some of the energy for a while longer than I had thought.

Jim Breslin

 

[BB1]

I always purge both regs and press the wing inflate button to remove residual gas from everywhere before unscrewing

 

[zoom5]

When removing the first stage from the tank valve you have to be careful not to turn the first stage. If you turn the whole first stage rather than just the hand wheel you can loosen the DIN o-ring and cause it to fall out.

 

[Jim Lapenta]

I have DIN regs from Oceanic, ScubaPro, HOG, and Sherwood. And at one time or another everyone has done this when I have tried to unscrew the reg too fast, forgot to hit both purges, or did not hit the inflator button to get the last of the air out. Other times I've gotten new O-rings in one of those save a dive kits that were too hard and it did not grab or was just the tiniest bit too small. I keep a dozen or so on hand at all times that I now get from only one source and have not had any issues. But just because it's been that way does not mean it won't again. Bottom line is be careful when taking off any reg from a tank. Keep orings on hand, and try to catch the ones that do drop.

As an aside I've had yoke regs do the same with residual air and seen the tank orings on them just fall out for presumably similar reasons.

 

[SDAnderson]

Residual charges that cause o-rings to pop on disconnect can happen for a number of reasons. Probably the most common culprit is the flow restrictor on the HP hose being a little too little or partially plugged. This is why divers often have to "purge twice" to get all the gas out of the system before disconnecting the unit from the cylinder. The HP hose and spg can trap quite a bit of gas and release it very slowly. If the flow restrictor is completely plugged, however, the spg won't function correctly and you shouldn't have a problem disconnecting the 1st stage from the cylinder after purging.

Less common but what may be happening in Bert's (and almost certainly in Jim's) situation: if the soft seal on the end of the second stage poppet is not seated correctly (or, less frequently, if the seal face is too thick), the unit can operate normally while under pressure but may not operate normally at low pressure. Some gas can get "trapped" behind the second stage valve that will only bleed out very slowly - if at all - when purged. On a flow bench this will manifest itself as an apparent residual charge on the IP gauge after a lengthy purge, exactly how much will be determined by the size of the gap and the force of the poppet spring. In the field, this may manifest itself as a residual charge that makes disconnecting the 1st stage from the bottle difficult, often resulting in blown o-rings. Unless you know what you're doing, checking for this should be left to someone who does, but an inspection of the poppet/seal should show no gap (zero, zip, nada) between them. Sometimes it's just a matter of pushing the seal all the way into the poppet, sometimes the seal stem may need to have a mm trimmed to allow it to seat properly in the poppet, less frequently the seal needs to be replaced with one of the correct size.

This isn't unique to Hog regulators, any similarly designed balanced second stage can have the same issue.