Why Piston vs. Diaphragm???

[Soggy]

I think it's more a way to resolve long deco's and malfunctioning regs. I don't think it ever shows up a first choice.

Yup, if you were low on gas, cold, or had some other problem where extending decompression would be impossible or a bad idea, only then would I switch because you might just end up with two malfunctioning regulators. Cave diving, it could be a useful technique if your stage fails on your way out and you were concerned about saving your backgas.

 

[squidster]

This Guy is getting his first regulater not building a oil platform.
If your diving rec limits lets say to a 100ft just get a scuba pro mk2 unbalanced piston
there is know reg simpler its been here since the 60s and is very reliable.
if you want a balanced reg oceanic has a very affordable piston reg.
diaphram regs have more parts ,but they are sealed,
but what can go bad on a simple reg like the mk2?

you can get one for 180.00 or less
if you go enviro sealed mk17 or apex or some other high tech regs, your going to pay 400.00 and up.
it depends on what you need.
I have a scuba pro mk11 diaphram reg its balanced 290.00-320.00
its the same reg as mk17 but doesnt have enviroseal , so what i dont plan to go under ice.
all scuba pro regs are cold ce rated.
people think they have to have the enviromentily sealed regs these days,for a rec diver i dont no if its needed.
go by how you dive and not always by the latest thing out there.
there are good points about piston type and diaphram regs,alot is just personal choice,and a matter of how its going to be used .

 

[DA Aquamaster]

People tend to assume that all diaphragm regs are sealed and that all piston regs are not sealed. In fact most first stages, piston or diaphragm are unsealed meaning that water is free to enter the ambient chamber.

In the past it was common for piston regs to be codl water protected by having their ambient chambers filled with silicone grease retained by a rubber boot while ambient chambers on diaphragm regs were sealed with alcohol or silicone oil retained with a second thin rubber diaphragm.

Today some piston regs are sealed with an O2 compatible filler in the ambient chamber while a couple designs use a schrader valve and a one way valve to maintain a dry chamber.

Current diaphragm regs are also mostly unsealed with a growing number of designs using diaphragm sealed dry chambers.

In terms of simplicity, unbalanced psiton regs are the hands down winner with one moving part, only 2 dynamic o-rings and no areas inside the reg past the high pressure exposed to high pressure air. They are as simple and as durable as a first stage can get.

Balanced piston regs and most diaphragm regs (all of which are currently balanced) tend to have parts counts and complexity levels that are about equal with a few balanced piston designs perhaps having a slightly lower parts count than the simplest diaphragm designs. op.

 

[scubapro50]

Have owned a Scubapro MK10 for over 20 years ... thats one regulator that has proven the reliability of the piston design.

 

[squidster]

Aquamaster,i have a question.
At what depth can you notice a real difference between a balanced Reg verses unbalanced?
This question is based on rec diving not tech
i know that a person who is exerting themself will bennefit from a higher flow of air.
but for a sport diver, the only difference may be the depth he is diving.

People tend to assume that all diaphragm regs are sealed and that all piston regs are not sealed. In fact most first stages, piston or diaphragm are unsealed meaning that water is free to enter the ambient chamber.

In the past it was common for piston regs to be codl water protected by having their ambient chambers filled with silicone grease retained by a rubber boot while ambient chambers on diaphragm regs were sealed with alcohol or silicone oil retained with a second thin rubber diaphragm.

Today some piston regs are sealed with an O2 compatible filler in the ambient chamber while a couple designs use a schrader valve and a one way valve to maintain a dry chamber.

Current diaphragm regs are also mostly unsealed with a growing number of designs using diaphragm sealed dry chambers.

In terms of simplicity, unbalanced psiton regs are the hands down winner with one moving part, only 2 dynamic o-rings and no areas inside the reg past the high pressure exposed to high pressure air. They are as simple and as durable as a first stage can get.

Balanced piston regs and most diaphragm regs (all of which are currently balanced) tend to have parts counts and complexity levels that are about equal with a few balanced piston designs perhaps having a slightly lower parts count than the simplest diaphragm designs. op.

 

[cerich]

Aquamaster,i have a question.
At what depth can you notice a real difference between a balanced Reg verses unbalanced?
This question is based on rec diving not tech
i know that a person who is exerting themself will bennefit from a higher flow of air.
but for a sport diver, the only difference may be the depth he is diving.

Unbalanced regs today you aren't going to at recreational depths provided the breathing rate is normal.

 

[squidster]

Unbalanced regs today you aren't going to at recreational depths provided the breathing rate is normal.

So up to about 120ft you most likely woudnt notice a big difference?

 

[Thalassamania]

Actually I don't think you'd notce much as long as you're tank is, say, 500 PSI above ambient.

 

[captain]

Depth itself will not have any noticeable effect on on breathing effort with either balanced or unbalanced first stages. Tank pressure will have an effect with diaphragm first stages becoming easier as tank pressure decreases and piston first stages becoming harder as tank pressure decreases. In both cases it would really only become noticeable at about 500 psi and below as thalassamaina indicated.
The unbalanced Le Spirotechnique Mistral double hose, single stage regulators were used by Cousteau below 300 feet.

 

[halocline]

I've had my MK2/R190 to 130 ft with no noticable increase in breathing resistance. If you want an affordable bullet proof reg the MK2 is a great choice; also, assuming this is your first reg, you can bet that someday you're going to want another regardless of what you buy. The MK2 then can be very useful as a stage reg or as a super-reliable back up on a dive trip.

One other thing that I personally feel is a good thing about the MK2 for a new diver; the unbalanced piston will give you a "warning" that you're really low on air by starting to breathe harder at 300PSI or so. Some people have posted that they think this aspect of an unbalanced reg is "dangerous", which is BS and probably right out of the mouth of a salesman trying to sell a "safer" (read: more expensive) balanced reg. If anything, the increase in breathing resistance at very low tank pressure is a safety feature.

At some point I got interested in older SP regs and bought a MK15/balanced adjustable, which does deliver air a little more smoothly. But I don't regret owning the MK2 at all.