Free flow during pre-dive checks

[wedivebc]

Don't understand why I hear so many regs have problems after servicing.........

I think it is because like DA mentioned, the 2nd stage poppet takes a shape after a while. When the tech replaces it then sets the cracking pressure to be as easy a pull as possible with out freeflowing. Then after a while a slight bleed off of air occurs. I usually set the cracking pressure just slightly tighter when the poppet has been replced. On my own regs I just adjust as nessasary.

 

[Delhi Diver]

I'm going to some AOW dives at a quarry this weekend. My Mares Abyss second stage leaks slowly (a slight but discernable hiss), making a funny vibrating noise when I inhale at the surface but working fine underwater. This also after servicing. Should I be concerned and not use it or is a slight leak something "normal" after servicing?

 

[DA Aquamaster]

A slight leak is never normal and indicates a problem with the reg.

What normally happens is the seat in the second stage develops a seating groove that then causes air to leak past the seat. This is a normal effect that the tech needs to anticipate, but sometimes in an effort to adjust the reg for minimum inhaltion effort, the tech gets it wrong and does not adjust the orifice in far enough and/or compress the spring in the second stage enough depending on the design.

If the hiss starts immediately on pressurizing the reg, this is most likely the problem. If the hiss starts several seconds to a coupel minutes after the reg is pressurized, it is probably a leaking HP seat in the first stage.

The vibration is normal, it's just the diaphragm vibrating due to a lack of dampening effect from the water. It's common after servicing and will either persist until the diaphragm adjusts to it's current stresses or until the next service.

 

[PhilEllis]

Don't understand why I hear so many regs have problems after servicing.........

A very simple answer for this question, I think. After service, many techs have no way of cycling the regulators to get a proper set. They simply purge the regulator a couple of times and assume this give the proper set. After some limited use, or after the seat has been in contact with the HP valve (poppett) for a few days, the set takes its set and is now not in proper adjustment.

This problem can be COMPLETELY eliminated by proper set of the seat seal to the HP valve. We almost NEVER have anyone return with a leaking regulator after rebuild. Of course, mistakes can still happen, but a good rebuilder must anticipate this problem and prevent it by using proper procedures. Anyway, my opinion. Thanks.

Phil Ellis

 

[Delhi Diver]

A slight leak is never normal and indicates a problem with the reg.

What normally happens is the seat in the second stage develops a seating groove that then causes air to leak past the seat. This is a normal effect that the tech needs to anticipate, but sometimes in an effort to adjust the reg for minimum inhaltion effort, the tech gets it wrong and does not adjust the orifice in far enough and/or compress the spring in the second stage enough depending on the design.

If the hiss starts immediately on pressurizing the reg, this is most likely the problem. If the hiss starts several seconds to a coupel minutes after the reg is pressurized, it is probably a leaking HP seat in the first stage.

The vibration is normal, it's just the diaphragm vibrating due to a lack of dampening effect from the water. It's common after servicing and will either persist until the diaphragm adjusts to it's current stresses or until the next service.

Understood, thanks. But is it safe to dive under these conditions?

 

[cerich]

Understood, thanks. But is it safe to dive under these conditions?

looks like you never got an answer. most of the time yes,a slight free flow or vibration isn't a huge problem. Is it smart? Nope, it could be an early symptom of a bigger problem that could involve all kinds of bad things from a massive free flow (hp seat failure) to flooded second stage (diaphragm dislodged).