piston vs. diaphragm

r&wc · Aug 16, 2006

i currently use a mares proton which is ok but starts to breath a little hard at 80' i am looking to upgrade and i am considering either an aqualung or scubapro, the biggest difference i can find between the two is the the aqualung uses a diaphragm and sp used a piston first stage, what exactly does that mean two me? is one better than the other?
most of my diving is in warm water and usually between 30 and 70 feet with the occasionall 90' as i gain more experience i do plan on doing more of the deeper dives

Diver0001 · Aug 16, 2006

Performance depends on a lot of factors but 'piston' vs 'diaphragm' is not one of them.

The 'piston' vs 'diaphragm' thing only becomes interesting when you're talking about diving in near freezing water.

I good way to start researching this is to take a read through the first few pages of threads on the regulator forum to see what people say about various regs and why.

R..

Scottri · Aug 16, 2006

I think what you should be asking are Balanced vs Unbalanced. Search through the Scubaboard Regulator Forum, there is a lot of very good information. Good Luck.

cobaltblue · Aug 16, 2006

It can also help if you look at the ScubaPro MK17. It's not a piston like the MK25 and I don't think there's anyone that can tell the performance difference. From what I've seen, the only thing that knows the difference is a machine. It also doesn't hurt that the MK17 is a bit cheaper even though it's sealed.

Hoyden · Aug 16, 2006

As long as you get a balanced reg, you won't notice any difference between piston and diaphram regs at the depths you normally dive. Honestly, if you never plan going deeper than 90', you would be fine with almost anything out there. My unbalanced MK2 breathes almost as well as a MK20 or DS4 at 70 feet.

r&wc · Aug 16, 2006

i wouldnt buy anything that isnt balanced, that much i know about, i was just curious as to everybody's opinion as to if i should even bother factoring the piston vs diaphragm into my decision making.
i do plan on eventually going deeper than 90', i figured if im going to purchase another reg i should get something that is going to suit my long term goals so i dont end up buying yet another in a year

Packhorse · Aug 16, 2006

Does your current reg have an adjustable 2nd stage?
If not this may explain why it breaths harder at depth.

r&wc · Aug 20, 2006

no adjustment, just the ventrui assist that mares puts on their regs

Ed Palma · Aug 20, 2006

With the quality of the regulators these days, plus the fact that you'll be doing mostly warm water dives, a piston or diaphragm wouldn't make much of a difference. And with the option for enviro sealing, maintenance of either type shouldn't be much of a problem.

padiscubapro · Aug 20, 2006

r&wc:
i currently use a mares proton which is ok but starts to breath a little hard at 80' i am looking to upgrade and i am considering either an aqualung or scubapro, the biggest difference i can find between the two is the the aqualung uses a diaphragm and sp used a piston first stage, what exactly does that mean two me? is one better than the other?
most of my diving is in warm water and usually between 30 and 70 feet with the occasionall 90' as i gain more experience i do plan on doing more of the deeper dives

You should not be having any issues at that depth.. It sounds as if the regulator is not properly tuned..

The cracking pressure and IP are important.. I suspect a low IP which you can check with an inexpensive guage (should be around 135psi or slighlty higer) that should be in EVERY divers kit.

even the least expensive proton (mr12) should perfrom well to all recreational depths.. I have used mr-12 based regs for many years and they have always perfomed well.. Before I switched to poseidons for deep diving (in the mid 90s) I routinely used a mr-12 - MK4 to depths over 200 fsw.. The first stage has changed little but the seconds have been improved.. The MK-16s have even better flow characteristics..

piston vs. diaphragm

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