recomended depth limits for unbalanced regs

[DA Aquamaster]

The only potential advantages of an unbalanced piston design like the Scubapro Mk 2 are that there are no o-rings with a pressure differential over the max IP of 140 psi (other than the one in the HP port) and they are dirt simple with one moving part and 2 dynamic o-rings.

They make nice low maintenence rental regs. They also work well on deco bottles where compact size is nice and high flow rates are not needed. They do however also work very well at depth with helium mixes and I have talked to a couple of cave divers who swear by them.

I agree with you on the lack of need for the through hole in the stem on a balanced diaphragm reg. The IP is basically constant, so as long as the area behind the stem is sealed from the HP air, the force otherwise exerted by the balance chamber could be compensated for with the spring adjustment pad.

[truva]

Yeah, they are simple I guess but I cannot not believe there is any real cost savings when you manufacture the thing to make it balanced to begin with. Then you wouldn’t be faced with the drawbacks.

I am not really anti-piston regulators by the way that was indeed a troll but the unbalanced piston is a bad design, yeah you may find a use for it but it wouldn’t cost any more to make it balanced in the first place.

Since most of the industrial stuff is diaphragm and valve and seat, I am more comfortable with these types. I only have to look after our stuff, which are Apeks DS4 and DST 2 of each all around 12 years old now. The 2 DST regs must have combined for over 1200 dives and are still on the original popets or valve stems whatever you want to call them. But we take real good care of the stuff and never even let dive guides change the tanks for us, they don’t care if any water get in them. I have had more than one argument about someone wanting to “check” our stuff.

I have enjoyed the topic and learned a lot thanks

Truva