Sealed vs unsealed

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Likely they don't want to put out the extra cash at service.
 
Never had an issue with a piston and any conditions I dive, MK 25 is a great reg, EVO is supposed to be better in the cold, any colder than what a MK 25 can handle I'm just not into it. That being said I'm diving deep6 Regs which are sealed diaphragms lately but if you are really concerned with a name brand the MK25/s620 ti listed is a great deal it seems.
 
So there is a difference between sealing a piston reg and a diaphragm reg that is sealed.

In a sealed piston, you have to pay extra because you need to fill it with lube.

In a sealed diaphragm, the design itself makes it sealed without using extra lube.

The point of sealing is to keep water from contacting the internal parts. If it's cold enough the water can freeze on the internal parts, which can lock it up and ruin your dive.

The sealing shouldn't have any impact on the performance nor any negative effects.
 
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Cold water aside, with proper post care unsealed should present no problem. I use an unsealed when traveling because it's smaller and lighter. MK17 vs MK11. On a side note I'm changing all MK11 parts to MK17 parts, save enviro sealing, which from what I've read, should then get me same performance as a MK17. Why? Because I'm bored, can easily get the parts, like a project and have more money than sense, well actually not much of either.
 
You're a warm water diver so.....sealing....to avoid freezing is not part of the equation.
That said, a sealed reg is just that.....sealed. Saltwater doesn't get IN to it. But it STILL gets into a lot of other parts, so the same care in soaking and rinsing is advisable.

After that it becomes kind of opinion. I have a Scubapro MK14/G250-a sealed diaphragm. It works fine. Been diving it in cold (42*-51*) water for years, and in warm water. It's a fine reg.
My wife has a ScubaPro MK20/G250HP (remember, I told you to take halocline up on his offer, much like this one?). It's an unsealed piston. It does exactly the same duty as mine. Probably, technically, if we both went to 200 feet and swam like hell hers might do better...maybe. We don't. In practice (regular diving), there's no functional difference.

IMO, hers needs a bit more extended soaking than mine since saltwater gets into the ambient chamber. Otherwise there really is not functional difference.

My thought is that you are badgering this issue to death. Pick a decent reg and go dive it.
 
I probably will get that reg from halocline after my trip. I had just about made my mind up when another reg came up for sale. I hate to pass up something better for the same money.
What has me confused, I guess, is I have had several people tell me to get an unsealed reg instead of one I was asking about.
I was wondering if there was a trade-off in performance with a sealed reg that was just necessary when diving cold. Since a sealed reg prevents a lot of problems I don't understand why all regs aren't sealed.
I know in my diving it doesn't make any practical difference, but questions like this bug me until I figure it out.
 
I probably will get that reg from halocline after my trip. I had just about made my mind up when another reg came up for sale. I hate to pass up something better for the same money.
What has me confused, I guess, is I have had several people tell me to get an unsealed reg instead of one I was asking about.
I was wondering if there was a trade-off in performance with a sealed reg that was just necessary when diving cold. Since a sealed reg prevents a lot of problems I don't understand why all regs aren't sealed.
I know in my diving it doesn't make any practical difference, but questions like this bug me until I figure it out.
There is no practical performance difference between modern sealed and unsealed regs. Why choose a design that requires careful cleaning to preserver its performance over a sealed diaphragm that is virtually bulletproof?
 
all modern regs will do the job for recreational diving in mild conditions. Just don't give any of them a ring.
 
There is no practical performance difference between modern sealed and unsealed regs. Why choose a design that requires careful cleaning to preserver its performance over a sealed diaphragm that is virtually bulletproof?

routine cleaning requirements are uneffected by the design of the 1st stage. In all cases, the challenge is drawing the salt water from unprotected threaded connections. The unprotected ambient chamber on a piston 1st is easily cleaned with 2 or 3 dunkings in FW which might take a minute or two.
 
OP, there is absolutely no disadvantage in choosing a "better" regulator than you actually need.
People are making too much of a fuzz about regulators.
I dove my Aqualung Calypso (low end) in water of 12°C/53°F and it worked just fine.
The closer you get towards freezing point, the more important the the regulator technology gets.
If you want to spend the money for the best reg you can think of, just buy it!
No downside, buy whatever you want!
 
https://www.shearwater.com/products/swift/

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