Saeed Al-Azom
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Could anyone help me to select Piston or Diaphragm Regulator and why?
Piston or Diaphragm Regulator
- Thread starter Saeed Al-Azom
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They both work pretty much the same way - changes in ambient pressure are transmitted either by a diaphrapm or a piston to open or close a valve. There are great regulators in both categories and it's really not possible to say "this kind is always better than that kind," there are other considerations that are also important.
Some "in general" guidelines:
The subject is, of course, far more complex than this simply synopsis. Search for "VANCE HARLOW REGULATOR REPAIR" and you'll find his book - anyone with an interest in how these things work should read it. For what it's worth, I own and dive with both kinds.
Some "in general" guidelines:
- Pistons can deliver more gas. This usually isn't much of an issue if you limit your diving to recreational depths.
- Pistons allow small amounts of water (and whatever is in the water) to get inside the regulator, making regular service more important. Though freeze-ups in very cold water can be a problem, for most divers this usually isn't much of an issue if you get your regulator serviced annually.
- Diaphragms are more complex, which can mean less reliable and harder to repair. This usually isn't much of an issue if you get your regulator serviced annually.
The subject is, of course, far more complex than this simply synopsis. Search for "VANCE HARLOW REGULATOR REPAIR" and you'll find his book - anyone with an interest in how these things work should read it. For what it's worth, I own and dive with both kinds.
captain
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reefraff:
I don't agree that diaphragms 1st stages are more complex or harder to repair. They generally contain fewer O rings over all and fewer O ring subject to movement than pistons. Also the IP is harder to ajust on pistons and generally require different springs or shims to do so where as a diaphragm's IP is ajusted simply with an ajusting screw. As for reliability I believe the diaphragm to be more reliable over the long run because there are no moving parts exposed to the water.
The Chairman
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Pull apart a piston reg after a couple of years and there is NO deformation of the piston. Do that to a diapragm reg and note how deformed the diaphragm appears. Most manufacturers contend that there is no variance in performance over the life of the reg. You can't tell that by looking at the parts.
captain
Contributor
NetDoc:
The diaphragm is rubber, naturally it will take some what of a set but it doesn't affect performance. It won't corrode like a metal piston and there is no place for corrosion, sand and salt to gather and cause it to stick like a piston.
True enough, but "verdigris" is a term only rarely associated with diaphragm innards. Muck, too, for that matter.NetDoc:
As to the complexity of one versus the other, I plead guilty to being half-asleep at 5:00 this morning and doing a bad job of editing (thinking, probably) what I was writing. Pistons = complex and harder to tune. Diaphragm = simple, easier to tune. Mea culpa.
Part of the problem is variations in designs, you can't really make generalizations. There are great designs from both. The best generalization I have seen is:
For people who are anal retentive about cleaning and rinsing their gear a Piston *might* be a better choice.
For people who are often lazy at cleaning gear a Diaphragm is usally a better choice.
Hmmm....maybe that's why I bought a dry sealed diaphragm reg...
For people who are anal retentive about cleaning and rinsing their gear a Piston *might* be a better choice.
For people who are often lazy at cleaning gear a Diaphragm is usally a better choice.
Hmmm....maybe that's why I bought a dry sealed diaphragm reg...
A dry sealed diaphragm reg does work well for people who are too lazy to rinse. However failing to rinse an unsealed diaphragm reg will result in corrosion in and around the ambient chamber, spring and spring adjustment pad. It can get really nasty in there.
If you ever use a reg for high O2 percentage deco mixes, one thing to consider is that the diaphragm itself is one great big fuel source.
If you ever use a reg for high O2 percentage deco mixes, one thing to consider is that the diaphragm itself is one great big fuel source.
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Saeed Al-Azom
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Thanks guys for the great information, I would like to add some important information:
I dive almost every day.
I dive in a worm water.
I do spearfishing.
Is that can make the choice?
I dive almost every day.
I dive in a worm water.
I do spearfishing.
Is that can make the choice?
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