balanced diaphragm vs. balanced piston

[DocVikingo]

Hi DivingDoc,

From my "Ask RSD" column in the Nov/Dec '99 issue of "Rodale's Scuba Diving" magazine:

"Which first stage regulator design is better -- piston or diaphragm?

In considering the piston v diaphragm issue, remember that the quality of design, material and workmanship is more important than the type of first stage. If you experiment with the best examples of piston and diaphragm models under recreational conditions (and somewhat beyond), you are not likely to notice any appreciable difference in terms of breathability, reliability or durability.

Divers who do very cold and/or dirty water sometimes prefer the diaphragm type as it may offer some extra protection against freeze up and contamination since it does not allow water into sections of the first stage, but piston types can be protected as well, such as by factory or after market environmental sealing and dry bleed systems that keep water from first stage moving parts (e.g, Sherwood regs). However, freeze up in modern piston-type first stages is quite rare even without special precautions.

Piston models are, on average, mechanically simpler, making them easier, although not necessarily cheaper, to service than diaphragm regs.

A number of major manufacturers produce both piston & diaphragm designs, and there is a wide choice of excellent models of both designs. Before buying, read reviews, ask other divers and try out those you are seriously interested in whenever possible."

Hope you found this helpful.

DocVikingo

 

[SDAnderson]

In my experience, this isn't an issue that the average recreational diver needs to spend a lot of time fretting about. Most regulators today (including most of the low-end stuff) are reliable enough that you don't need to worry about a failure - so long as they are well maintained. If you're diving in sub-40F water or diving in sub-130ft water, you aren't an average recreational diver and you probably should consider such arcane matters in greater detail.

I dive both regularly. Most of the failures that I've seen have been the result of sloppy service technicians - a much more important issue.

Steven

 

[DivingDoc]

Just because you two are so knowledgable and because I have your attention, I am currently trying to decide between a Mares Abyss and a ScubaPro S600/MK25.

As far as a reg is concerned, I want most of all easy breathability then reliability, then dry breathing (doesn't let water in in different positions). Since this is probably going to be my first and last reg purchase, I don't care about a $200.00 difference between the two regs.

I tried a Scubapro S600/MK20 when I went diving in Coz in Jan and loved the way it breathed. It has a lifetime guarantee, including parts.

The Mares claims to add some warmth and moisture to the air because of the metal parts (which might increase comfort), is a diaphragm (so will keep contaminants out), but is heavy and has a stiff hose (not so good for my TMJ). I have never tried it in the water. It does not have a lifetime warranty and costs $100.00 for an overhall.

I am also considering a the Zeagle Escape BC vs. the LadyHawk. The former is cheaper, and I think fits me better, but is at a different LDS than the ScubaPro reg. Is it a problem buying a BC from one shop and a reg from antoher, with the integrated Octo-plus or Air2 or whatever?

Also considering a Suuto Vytek vs. an Aeris Atmos Pro with gauges.

What advise would you give me on these choices? I am leaving for Coz on the 19th of June.

ET

 

[SDAnderson]

Hey, easy on the butter. The other guy knows something. I just stay at a Holiday Inns occasionally, that's all.

As far as regs go, you've decided what your priorities are and that's half the battle. For recreational divers I'd suggest considering these factors: reliability, breathability, servicability and weight. Price and a studly design are optional issues.

I like SP regs and have a couple in my collection. The whole line is workhorse reliable and can be serviced almost anywhere in the world without waiting for parts, should the need arise. I don't have first-hand experience (too poor) with the S600, but I've seen them and they're excellent regulators.

I'm not nuts about aluminium and titanium in regulators. Great for weight considerations, but there are metal fatigue issues and flamability issues that make me nervous. That said, Mares has a pretty decent reputation and I don't think you'll regret buying one.

Skip the Air2 and buy a second second stage to use as an alternate. Although the Air2 makes sense in some respects, in the long they create as many problems as they resolve. Especially for those with less experience, go for the full-blown alternate. Nonetheless, if your LDS tells you that you have to buy your regulator from the same shop as your BC, make certain your wallet's in your pocket and head for the door.

You seem to be reaching what I call the "Skywalker" stage of equipment purchasing: you've done your research, you know what you want and why you want it, but you don't trust yourself enough yet to be comfortable making a decision. My advice in situations like this is simple: Trust the Force, young Jedi. Let your feelings guide your decision. Besides, why should you be any different than the rest of the world? Half the nightmare of this sport is replacing gear every few years as the technology leaves you in the dust...in the meantime, get wet.

Steven

 

[DivingDoc]

Originally posted by reefraff
Hey, easy on the butter. The other guy knows something. I just stay at a Holiday Inns occasionally, that's all.

As far as regs go, you've decided what your priorities are and that's half the battle. For recreational divers I'd suggest considering these factors: reliability, breathability, servicability and weight. Price and a studly design are optional issues.

I like SP regs and have a couple in my collection. The whole line is workhorse reliable and can be serviced almost anywhere in the world without waiting for parts, should the need arise. I don't have first-hand experience (too poor) with the S600, but I've seen them and they're excellent regulators.

The guy that wants to sell me the Mares says that piston regs are bad for ocean diving because the water gets in and corrodes the parts, so unless you thoroughly clean them after each use, like soak them overnight, the reg may not work -- is this correct about pistons?

Originally posted by reefraff
Skip the Air2 and buy a second second stage to use as an alternate. Although the Air2 makes sense in some respects, in the long they create as many problems as they resolve. Especially for those with less experience, go for the full-blown alternate. Nonetheless, if your LDS tells you that you have to buy your regulator from the same shop as your BC, make certain your wallet's in your pocket and head for the door.

OK --what problems do they create? All the LSD's seem to want to sell you the alternate that's integrated with the BC -- must be an incentive there somewhere.

While I've got your attention -- what do you think of Aeris vs Suunto dive computers??

Thanks again for your expert advice.

 

[hannesv]

First, thanks for all the incredible info on this. My 0.02c worth (which incidently is about $0.0002)- Scubapro Mk25 with S600 is probably one the best there is right now. Total overkill for rec diving. But to muddle the waters a bit, when on a tech dive with Mk25 and S600, my backups are on a ScubaPro Mk2+ and R380. So the Mk 25 piston, and the Mk2+, a diaphragm. So to choose or not to choose. if you have the bucks go for the Mk25 and S600, you will never be sorry. Which ever you choose, for rec diving both is more you will ever need.

 

[Max]

About six weeks ago I received my Sp S600/MK25 ($306 from Diveinn) and a few days later Mares abyss (from Leisurepro). Strictly speaking about comfort (after 15 ocean dives) for me the Scubapro is a pure delight. As far as air flow, both seem to do a great job. The only advantage to the Mares abyss is that it can double as a self defense weapon, sturdy as can be.
max

 

[SDAnderson]

Originally posted by DivingDoc

The guy that wants to sell me the Mares says that piston regs are bad for ocean diving because the water gets in and corrodes the parts, so unless you thoroughly clean them after each use, like soak them overnight, the reg may not work -- is this correct about pistons?

Location dictates that most of my dives are freshwater, with only 40 - 50 saltwater dives a year I don't know that I'm qualified to speak to this from experience. I can say that salt water seems to eat everything it touches but that I've never had a problem with unsealed regulators being substantially more susceptible than their breathren. Rinse thoroughly (I've never rinsed a regulator overnight in my life) and service annually and you should be fine with whatever you choose.

OK --what problems do they create? All the LSD's seem to want to sell you the alternate that's integrated with the BC -- must be an incentive there somewhere.

Next time you're in the water, try this drill. Or at least imagine it: Your buddy is experiencing a sudden out of air emergency, typically from a blown hose or burst disk. It happens. He's scared and maybe half-drowned and flailing around like a tuna with a hook in it's mouth. You've donated your primary and are trying to maintain control of the situation while breathing from your alternate. Your alternate, being an Air2, is also your inflator control, so you have to continously remove your regulator from your mouth as you ascend in order to vent air from your bc. Add to that, the hose on the Air2 is very short, so your head has a severely limited range of motion - basically you can't look to the right or up with the regulator in your mouth. I've never seen anyone practice this drill with a buddy that didn't get out of the water with their confidence in their Air2 seriously shaken - this is serious task loading. Streamlining is a good thing, but this is a high price to pay for it.

The lesson:

• Put your primary on a long hose and plan on donating it in an OOA emergency. A panicked diver is going to decide which regulator he wants, and it's most likely going to be the one he sees in your mouth with air coming out of it.
• Put your alternate on a bungee around your neck. Forget the scumball in the Golden Triangle stuff.
• Practice switching regulators at the start of every dive during your 15' bubble check. You'll know that they both work and where the alternate is.

Can't speak to your computer question.

Steven

 

[DivingDoc]

Originally posted by max
About six weeks ago I received my Sp S600/MK25 ($306 from Diveinn) and a few days later Mares abyss (from Leisurepro). Strictly speaking about comfort (after 15 ocean dives) for me the Scubapro is a pure delight. As far as air flow, both seem to do a great job. The only advantage to the Mares abyss is that it can double as a self defense weapon, sturdy as can be.
max

That's an amazing price. My LSD has the SP S600/MK25 for $675.00. When you order from DiveInn, does the lifetime warrenty still hold? Where do you get it serviced?

Did you notice any difference in comfort between the Mares Abyss and the SP? Mares claims to have some advantages as far as warmth and moisture of the air you get from it because of condensation on the metal surface. On the other hand, the Abyss has a stiff hose (so I'm told) and is mucho negatively boyant -- so those could aggravate one's TMJ. What's your opinion there?

Thanks alot,
ET

 

[wch]

I was at my LDS on Friday and the owner showed me a bulletin from SP asking that their dealers not service SP products bought online. So you could run into problems on the warranty. The whole thing is bogus, as SP is selling their product to DiveInn. What if I was on vacation in Spain, England, or anywhere else that sells SP products for half the price as in the US and bought their product? Still all in all I really like SP products.

A note on the Air2:
If you were to get the Ladyhawk it has a right shoulder dump so you would not have to take the Air2 out of your mouth to vent. Also if you tear open the Velcro tab it will allow a greater range of head movement, not as much as the bunged octo, but you will have no problem looking at your buddy and looking up.