Hey all working on setting up a seperate set of doubles for eventually going tech. Here is my question Balanced piston or Diaphram. which is better for going tech. Now I just want to put this out I am not looking for what you have I am looking for the pros and cons for each and is there is a preferred type of first stage.
Piston or Diaphragm
- Thread starter dashthrash
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This is one of those Ford vs Chevy type questions.
Both will do the job. Either have the features and durability to withstand tech use, hose routing is more improtant than style. The one area that diaphgarms do have an advantage is they are easier/cheaper to enviromentally seal for cold water use, otherwise the differences are just that differences.
Both will do the job. Either have the features and durability to withstand tech use, hose routing is more improtant than style. The one area that diaphgarms do have an advantage is they are easier/cheaper to enviromentally seal for cold water use, otherwise the differences are just that differences.
HenrikBP
Contributor
I dive a set of Apeks Tek3 regs - they're really just "dolled up" DS4 regs 
- and they route the hoses neat and tight. But if I gotta be honest - the way Scubapro piston regs route with the inflator and back-up hose coming out of the bottom port is pretty slick as the hoses route without the sharper bends my Tek3 regs cause ... and I am mentioning my regs just as a reference to how hose routing differs but is important when you're setting up doubles. The SP piston regs *may* also give you a fraction more room to get your head back when you're in horizontal trim.
I went with diaphragm for my doubles because of the environmental sealing - as Herman mentioned.
- and they route the hoses neat and tight. But if I gotta be honest - the way Scubapro piston regs route with the inflator and back-up hose coming out of the bottom port is pretty slick as the hoses route without the sharper bends my Tek3 regs cause ... and I am mentioning my regs just as a reference to how hose routing differs but is important when you're setting up doubles. The SP piston regs *may* also give you a fraction more room to get your head back when you're in horizontal trim.I went with diaphragm for my doubles because of the environmental sealing - as Herman mentioned.
Karl_H
Contributor
Generally, most people agree the hose routing on the piston regs is better than the diaphragm equivalents, sealed diaphragms are more appropriate for cold water diving (although many people are using unsealed pistons such as the Mk25AF with no problems).
The piston first stages will generally give more flow but realistically that makes no difference unless you plan on setting a new world record for the number of people breathing from a first stage, or diving without a second stage so as not to limit the overall flow.
The new Hog D3 sealed diaphragm regs are very interesting, sealed diaphragm regs with almost the same routing as pistons – given the comments above I’d say they are may be worth a closer look?
The piston first stages will generally give more flow but realistically that makes no difference unless you plan on setting a new world record for the number of people breathing from a first stage, or diving without a second stage so as not to limit the overall flow.
The new Hog D3 sealed diaphragm regs are very interesting, sealed diaphragm regs with almost the same routing as pistons – given the comments above I’d say they are may be worth a closer look?
ajduplessis
Contributor
Maybe you can give us a bit more info what type of tech diving you plan to do (ice diving, cave diving, deep open water etc). With regards to hose routing the 2 best options IMO are: Scubapro MK25 (piston) and Apeks Tec3 (diaphragm). Both are fantastic, I use both, Tec3 for cave, MK25 for deep (300ft+) OW dives.
OP
The type of diving that I am interested in is going to be deep openwater
ajduplessis
Contributor
Then either will do fine. SP MK5 is a great 1st and I prefer it for all deep openwater diver (300ft+)
Most of my diving is technical (deep wreck on Trimix or Heliox). When using open-circuit, I prefer Apeks Regulators (Diaphragm first stages). I've found that they offer superb gas flow, easy maintenance, simple adjustment of intermediate pressure and a sealed mechanism that affords protection from all types of contamination and freezing.
The over-balanced diaphragm design of this Reg, provides increased intermediate pressure to the second stage (more than traditional balanced models), as the diver descends to greater depths. This increased intermediate pressure compensates for the increased density of the breathing gas by allowing a larger volume of gas to flow through the system on demand. This results in excellent performance regardless of depth.
The over-balanced diaphragm design of this Reg, provides increased intermediate pressure to the second stage (more than traditional balanced models), as the diver descends to greater depths. This increased intermediate pressure compensates for the increased density of the breathing gas by allowing a larger volume of gas to flow through the system on demand. This results in excellent performance regardless of depth.
It's not a Ford Vs. Chevy argument. And no, they both won't do for any spot on your rig. Here's why...
Two weeks ago I did a dive to 287'. In my gearing up, I mistakenly grabbed my Piston reg for my drysuit INSTEAD of the proper regulator. Guess what. A Piston reg will not inflate a drysuit at 287'. It's only putting out 140psi. At 287' you are looking at about 127psi pushing back. It took FOREVER to get the squeeze off.
Now, imagine if I had mistakenly used that 1st stage for bailout instead of drysuit inflation. I'd have been screwed.
Fact of the matter is... to answer which regs? Piston or Diaphragm: Both.
Piston regs are bullet proof. They just work just about forever, usually without fail. So, we use them for 100' and shallower like on deco bottles and stage bottles. We use Diaphragm regs on deeper dives because regardless of depth they always put out 140psi.
Edit*
Truth be told, I was assuming we were talking about unbalanced regs. As I have a buttload of them and use them for rental and training and stage and deco bottles. Upon further reading, realized you MIGHT be talking about balanced piston regs, which changes my story completely.
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Superlyte, doesn't a balanced piston solve that problem of output varying with depth?
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