Sealed vs unsealed

[207diver]

I personally prefer a sealed diaphragm over a sealed piston if you are going the sealed route. From a service standpoint it is a much easier process. Unless you can get your hands on an older Sherwood those are bulletproof and cheap to maintain.
A unsealed diaphragm my require a couple extra dunks in fresh water to unsure the ambient chamber is clean but that is all. if you have the extra cash go for a sealed reg. My personal preference is the mk17 or some variation of it e.g. Tusa r700 or halcyon's version. I dive the tusa rs790 combo I s a solid reg at an affordable price and can be service with Scubapro kits which are available anywhere.
If your staying in warm water or shopping on a budget go with a cheaper unsealed diaphragm there are tons of choices. A mk11 has the same proformance as a mk17 just not sealed and at a great price point.

 

[rhwestfall]

Here is a problem with sealing piston regs:

if done incorrectly, salt water gets trapped, and it's bad from there....

A sealed diaphragm, like the aforementioned MK-17 is a much better solution....

 

[tbone1004]

people recommend against sealed regs for multiple reasons

for sealed diaphragms it's an initial cost thing and they are going on the premise of if you don't need it, don't pay for it. that said, it really does help if you're diving in salt water from a maintenance standpoint and they aren't that much more expensive

for sealed pistons, I don't believe in sealing them because of the insane cost of doing it, and the picture that bob posted above. Too much risk, not enough reward. If you need a sealed regulator, you should buy a diaphragm because it seals easily.

This day in age, there is a reason that all except essentially one manufacturer has abandoned pistons for their top regulators. Atomic and Scubapro are essentially one mfg since Atomic was founded by p!ssed off Scubapro engineers. Aside from those two, TUSA *which is basically Scubapro since they are licensed to manufacture their designs so they don't actually count*, and Genesis/Sherwood are the only company I can think of that have high end piston regulators.
Apeks, Aqualung, Poseidon, AUP/Oceanic, Zeagle, Dive Rite, Deep6, OMS, HOG, Cressi, Mares, and I'm sure I'm missing a couple are all firmly in the diaphragm game for their top end regulators. Many will have a piston for various reasons, rental/inflation regs *they are much cheaper to make*, O2 *they do handle pure O2 better, but if you service at proper intervals it's a nonissue*, and that's about the only two reasons I can see to use pistons. People talk about their flow rates, but the regs are limited by the flow rate of the valve and the good diaphragms can all beat a valve, so there really isn't a justification for it.
This does NOT mean that pistons are bad, they are damned good regulators, especially the MK25 and the Atomics, but if I had the choice between an Atomic and a Deep6? I'll take the Deep6 every time, and the vast majority of people that I know and dive with would do the same.

 

[Lorenzoid]

people recommend against sealed regs for multiple reasons

for sealed diaphragms it's an initial cost thing and they are going on the premise of if you don't need it, don't pay for it. that said, it really does help if you're diving in salt water from a maintenance standpoint and they aren't that much more expensive

DRIS advertises the HOG D1 sealed version at a $20 premium over the unsealed. (I wasn't even aware HOG still made the unsealed version.) Unless one is buying a lot of regulators, it seems to me that $20 is a trivial cost.

 

[tbone1004]

DRIS advertises the HOG D1 sealed version at a $20 premium over the unsealed. (I wasn't even aware HOG still made the unsealed version.) Unless one is buying a lot of regulators, it seems to me that $20 is a trivial cost.

those are probably overstock. People like Mike at DRiS, Edd at Cave Adventurers, and John at Northeast Scuba Supply like to buy almost pallet quantities of stuck to get some great pricing, so it's likely that Mike still has some left over from when they stopped selling them.
The bigger argument is usually when looking at a manufacturers unsealed option vs. it's sealed options, but it usually is a completely new regulator vs. an unsealed version of another. I.e. with Apeks you don't get the option of the DST, FSR, or FST in an unsealed version. You can only get the DS4 unsealed which is the US4. It's a $70 difference between the XTX20 and XTX40 which are the same aside from the diaphragm on the first stage. It's a worthwhile cost in my opinion and the only unsealed diaphragm I would buy is the Poseidon MK3 because it was designed to not need one for cold water, but more importantly the size of the openings are large enough that cleaning it out is easy. Cleaning the chamber of an unsealed diaphragm is basically impossible without removing the cap, so you have to be extremely diligent about that. At least the unsealed pistons allow water to move through their chamber. If you go unsealed, go piston for that reason alone, but if you are choosing between a similar sealed diaphragm and piston, I really can't see any rational argument for piston.

 

[redacted]

Here is a problem with sealing piston regs:
View attachment 395393

if done incorrectly, salt water gets trapped, and it's bad from there....

A sealed diaphragm, like the aforementioned MK-17 is a much better solution....

Or not done at all. Do you know the history of that damaged Mk10? I would conclude it was put away without being cleaned resulting in the verdgris. In fact, it looks like that had happened a number of times in the past resulting in the loss of chrome plating on the piston head o-ring sealing surface in the Mk10 body. Once the chrome is compromised like that, continued episodes of inadequate cleaning cause the damage to snowball.

I have nevr tried to seal a piston 1st. I have bought a couple that were sealed and it was quite a job cleaning out the packing but they were like new once cleaned.

 

[rhwestfall]

Do you know the history of that damaged Mk10?

The one that was claimed by the POS seller, or the reality? Needless to say, I was not happy. I will say though, some Flitz and a dremel, and it is purring along fine. It will never see salt water again, and will never be sealed.....

 

[redacted]

The one that was claimed by the POS seller, or the reality? Needless to say, I was not happy. I will say though, some Flitz and a dremel, and it is purring along fine. It will never see salt water again, and will never be sealed.....

What makes you think that damage is related to the reg having been previously been packed. It looks like it was not packed when you received it.

 

[rhwestfall]

because that is what it looked like after I got the grease (silicone) out of it... this was after a scrub and an ultrasonic bath....

 

[Centrals]

I have asked about a lot of regs here, and when I ask about one that is sealed someone comes along and says I don't need a sealed first stage.
I was wondering why I would be discouraged from buying one.

We are all entitled to our own opinion.
I have used non-sealed and sealed Apeks regs in the past but had since replaced all the non-sealed version with sealed one.