Regulator Roundtable Q&A

[Dive Right In Scuba 2]

Wondering about regulators? Wanna understand what makes them "tick"? Let's hear your questions!

Not only do we sell most major brands of regulators, we also service quite a few too! So use our experience to help you with those burning regulator questions.

The "phone lines" are now open...so ask away!

 

[Shaun_Mc]

What are the practical differences for a regular rec diver between piston and diaphragm first stages?

 

[buddhasummer]

I believe Unless diving really cold water, generally recommended as under 50f or dirty water in which case a sealed diaphragm reg is probably a better option, nothing really. I dive both functionally I notice no difference. I do take more care in rinsing the piston reg though as the ambient chamber is exposed to the elements as opposed to an environmentally sealed diaphragm 1st.

 

[Agility]

What are the practical differences for a regular rec diver between piston and diaphragm first stages?

With the exception of warm water regs (e.g. the Apeks flight) practically none.
Any new regulator will provide a recreational diver with all the gas he or she needs if it is maintained properly.

Most regulator choices are a question of taste.
I love my Poseidon and Apeks regs and many of my buddies would never swap their Scubapro Pistons for mine.

 

[Dive Right In Scuba]

Great answers guys!!

Another quick bit:

Diaphragms are best for cold water, they easily just fully seal out the water or contaminates. I believe they are great for all waters as they also keep out salt and everything else.

Piston pushes more air, so they do tend to breath better. This is changing, and they are getting closer and closer together as the manufacturers keep working on the breathing effort. You can pack these with Christolube to make them sealed. It's expensive, but does do the job.

I dive Atomic ST1s and love them. I also have some Hollis 500's that are diaphragm that I love too. They don't breath the same, but I like them for different reasons.

As a rec diver, I wouldn't worry about that yet. The questions I would worry about are, what is your dive environment? What temps will you be diving?

 

[Shaun_Mc]

I'll be diving northeast mostly with some tropical thrown in when I can afford to

 

[CptTightPants21]

I'll be diving northeast mostly with some tropical thrown in when I can afford to

You are going to want to get either a sealed piston with christolube or a diaphragm if you plan on diving deep and/or in April and May. I would go with the diaphragm, but plenty of people up here go with the hassle of christolube and the piston reg.

I have a buddy whose piston reg free flowed in April at 85ft. Lucky he had a buddy and they just went up the line, but it was a rude awakening for who was, at the time, a new diver.

Dutch Springs was between 38-40 degrees first week of May of this year, never had a problem with a free flow using my Apeks.

 

[herman]

Great answers guys!!

Another quick bit:

Diaphragms are best for cold water, they easily just fully seal out the water or contaminates. I believe they are great for all waters as they also keep out salt and everything else.

Piston pushes more air, so they do tend to breath better. This is changing, and they are getting closer and closer together as the manufacturers keep working on the breathing effort. You can pack these with Christolube to make them sealed. It's expensive, but does do the job.

I dive Atomic ST1s and love them. I also have some Hollis 500's that are diaphragm that I love too. They don't breath the same, but I like them for different reasons.

As a rec diver, I wouldn't worry about that yet. The questions I would worry about are, what is your dive environment? What temps will you be diving?

You are a little off base here. Some pistons (flow through design) are capable of FLOWING more volume of gas than a diaphragm reg however this is irrelevant because any modern first stage regardless of design can flow more gas than a diver can use or a second stage can flow. Work of breathing and cracking pressure are a function of IP ( intermediate pressure) and the design of the second stage. Assuming the first stage is balanced (all modern diaphragm and flow through piston are) the IP stays constant (more or less) so the work of breathing and cracking pressure are solely determined by the second stage. In addition, many mid to upper price second stages are also balanced, which takes IP changes (within reason) out of the picture and work of breathing and cracking pressure are determined by just the second stage. Any balanced modern first stage will not make any difference in performance when paired with a modern second stage and if the second stage is balanced, even pairing it with an unbalanced first will have no impact on how the second stage performs. In short, the first stage does not matter, what does is the design and quality of the second stage.

 

[halocline]

Piston pushes more air, so they do tend to breath better. This is changing, and they are getting closer and closer together as the manufacturers keep working on the breathing effort. You can pack these with Christolube to make them sealed. It's expensive, but does do the job.

One of the nice things about this forum is divers can get unbiased, in depth information from other divers who know quite a bit about regulator function. This is very different from the sales-driven dive shop B.S. that seems to pollute scuba publications.

If you're going to invite divers to ask you questions about regulator function on this forum, especially as a dive shop, please try to provide accurate answers instead of the usual drivel, ok?

1. Piston regulators do not breathe better because the "push more air". All decent first stages provide far higher air flow than either 2nd stages can handle or tank valves can flow. First stage performance is about IP recovery and stability. There is no practical difference between high quality diaphragm and high quality piston designs in this area. Further, there are two very different kinds of piston designs with very different flow rates.

2. Regulators are not really changing. There have been no significant performance upgrades in regulator design in decades. The tried and true US divers balanced diaphragm (a la conshelf) and the tried and true SP balanced piston (MK5) basically set the standard 30 years ago (or more) and have yet to be surpassed in terms of real-world dive performance.


Regulators have gotten a lot more plastic, a lot more gizmos, and a lot more hype in recent years, I'll give you that. But they all basically do the same thing; step down tank pressure to ambient so that it is breathable. The 2nd stage (as Herman mentioned) is really what determines the feel and effort required to breathe.

 

[buddhasummer]

I own a M25/G260 and various Apeks, to me all breathe equally well. I've never thought wow this MK25 is giving me more air. YMMV. Cheers.