Balanced Diaphragm or Piston ?

[impulse]

Hello,

Now a days I try to decide on a reg. But there are too many brands and too many models under each brand. That's why everytime I decide to buy a reg I find something new and decide to buy that.

Today at a LDS, I figured out that atomic regs have a piston system on their first stage. And I also learend that piston system is better than the balanced diaphragm system which apeks regs have on their first stage. So is this really right?

I think in a balanced diaphragm system there are too many pices working togather (I think 7 pices) but in a piston system there are just two pices, the piston itself and a spring. So the more simple a system is it the more effective and durable ? Piston system looks more simple than the diaphragm system.

I really need some technical information here.

Thank you.

 

[OldNSalty]

I predict a lot of conflicting information with no resolution found.

 

[msg]

 

[rstofer]

As I am unfamiliar with diving on Mars, I'm not sure what to say.

If you actually dive in warm water, it doesn't matter much what you buy. But, if you dive in cold water, less than 50 deg F, then you might want to consider an environmentally sealed diaphragm regulator.

Oceanic, among others, clearly states in their User Manual that their piston regulators are not to be used below 50 deg F.

There are some unbalanced piston regulators around but most anything you will actually want to buy will be balanced. Either piston or diaphragm.

Here's an article that states that the diaphragm regulators have fewer moving parts: Scuba Regulators

Somehow, I think you are going to have to narrow down the set of regulators you are considering and then reposting.

Otherwise, just buy the ScubaPro Mk 17/G250V and call it a day. Oh, wait, maybe the Oceanic Delta4/FDX10 as it is the cold water regulator of choice by the US Navy, US Coast Guard and NOAA. Either of these regs will work very well in cold water.

More important might be which regulator you can get serviced in the area where you expect it to be serviced. You probably should go for a regulator with free parts if you plan to dive on Mars.

Richard

 

[LeadTurn_SD]

Hello,

Now a days I try to decide on a reg. But there are too many brands and too many models under each brand. That's why everytime I decide to buy a reg I find something new and decide to buy that.

Today at a LDS, I figured out that atomic regs have a piston system on their first stage. And I also learend that piston system is better than the balanced diaphragm system which apeks regs have on their first stage. So is this really right?

I think in a balanced diaphragm system there are too many pices working togather (I think 7 pices) but in a piston system there are just two pices, the piston itself and a spring. So the more simple a system is it the more effective and durable ? Piston system looks more simple than the diaphragm system.

I really need some technical information here.

Thank you.

I'll keep that in mind the next time I service one of my balanced diaphragm regs.... maybe I'll just throw out a few of those "too many pieces" so it will be more effective and durable

Serious Answer: For most folks, either a good quality balanced diaphragm or balanced piston design will make them perfectly happy.

The balanced piston designs have the potential to provide greater airflow than the balanced diaphragm.... but this is in most cases "wasted" since both diaphragm and piston designs produce more flow than the best 2nd stages can use.

Piston designs are mechanically simpler than diaphragms, but diaphragms are far from being "complex", and are not less reliable than pistons. Some feel than in certain instances the opposite is true (that diaphragms are more durable) because there is less water intrusion into the 1st stage (because of the diaphragm).

Diaphragms are also in general less likely to "freeze" flow in extreme cold conditions.

For most recreational dives, either design will make you very happy. So just pick the regulator your want, and have fun.

Best wishes.

 

[herman]

What you have actually learned is some LDSs will feed you a line in a second to make a sale....Diaphrams are bad...wonder why USD/Aqualung has been making them of over 40 years and Apex diaphrams are well respected in the tech diving community...they work and work well. Not there is nothing wrong with a good piston reg, some of the simple piston regs like the Scubapro Mk2 and any of the Sherwoods are super dependable and easy to service. Leadturn has it right, fact is pretty much any reg will do 90% of rec divers. Get a mid range model of any of the major brands and go dive.

 

[halocline]

I can almost hear the salesman talking from your post. If you have an ipod, you might want to bring it next time you visit that store.

Some piston regs are very simple, some are more complicated. Some diaphragm regs are very simple, some are more complicated.

The guy wanted to sell you an atomic. I don't suppose that anything to do with the fact that they're pretty pricey, did it? They are excellent regs, but almost certainly much more than you would ever need.

 

[scubafanatic]

I can almost hear the salesman talking from your post. If you have an ipod, you might want to bring it next time you visit that store.

Some piston regs are very simple, some are more complicated. Some diaphragm regs are very simple, some are more complicated.

The guy wanted to sell you an atomic. I don't suppose that anything to do with the fact that they're pretty pricey, did it? They are excellent regs, but almost certainly much more than you would ever need.

...while Atomics CAN be expensive, they don't have to be expensive...take a look at the 'Z' series ones. I'm diving both 'piston' regs (Atomic M1 + T2) as well as diaphragm ones (Apex XTX 200 (2) ....Aqualung Titan LX (1).....plus half a dozen Poseidon Jetstreams....and several Mares regs) ......and honestly, they all work just fine. I really woundn't spend too much time worring about piston versus diaphragm...other than to say, if you dive in a cold/silty environment...AND choose a piston reg, make sure to get the environmental sealed 1st-stage kit installed.....sometimes that 'kit' already comes as 'standard' on a piston reg anyway. Also, Atomics use Christolube-filled 1st-stages when they are environmentally sealed, which is cleaned out/replaced when serviced....which may add an extra $ 30 - $ 40 to the service cost.

 

[deadly_risk]

Having really no knowledge one way or the other, from this video, it looks like the Mk17 (balanced diaphragm) has fewer parts, and is simpler than the Mk25 (balanced piston).

YouTube - SCUBAPRO MK25 and MK17 First Stages in 3D

 

[Gerbs]

Hiya,

The most obvious answer to the question of which regulator to buy:

The same as the guys you dive with!

If they are still alive, the regulator is suited to the diving they are doing, and the LDS is likely to be set up for servicing.

My knowledge of regulator technology is as follows:

Piston Regulators:

Small Metal Bit with the gas expansion (endothermic) at one end with the water (that sets up the regulator to provide to ambient + IP (Surface) at actual depth) at other end.

Diaphragm Regulators:

Metal near gas expansion pushes on rubber disk, where water pushes on other side.

Expanding gas from Tank Pressure to Intermediate Pressure takes energy away from the surroundings. This makes the 1st stage get cold while working... Now, the basic idea is: don't get water cold enough near moving parts to freeze, cause bad things happen.

There are the following schools:
Keep the moving bits in air, so no ice can form near the piston (Sherwood)
Keep the water isolated from the cold (Membrane - Apeks, Mares et al)
Sod it and get the warmth from the water around to melt the ice (Piston designs)

Some take it to extremes - Diaphragm + keep the water away from even that through a non-freezing fluid + get as much heat from the surrounding water to the part that does the expansion. This would be Apeks + Mares (with Ice Kit).

From experience in diving in cold water (4°C/39°F territory) with others, Mares MR12/MR22/V32/MR42 (no ice kit, with Abyss or Proton Ice first stages!) as well as any Apeks work very well.

I'd like to second rstofer in getting a regulator that you can get serviced locally (Apeks tolerate irregular servicing better than Mares, btw).

If you are diving in sub 10°C (50°F) water, also look for "Certified Cold Water EN250". This is a euro standard for cold water regulators. For a more stringent test criteria, see what the US Navy has to say on regulator testing.

In either case,

1. What can be serviced locally
2. Which is certified EN250 or US Navy
3. .. and used by the others you dive with for similar diving

will be something that most likely works for you.

I own a Mares Abyss MR22 (~2004) and a similar vintage Proton Ice V32. Neither has let me down (if I service them occasionally). Most of the people I dive with use either similar or Apeks, with a few using Beuchat or Poseidon.

Other criteria to consider is hose routing (where are the HP and IP ports to put regulators, inflators and gauges on), as well as size (do I want to lug 2 kg /4,4lb of regulators around every time I fly to go diving?).

For cold water use two first stages and ditch this "octopus" malarky pronto. Don't put primary buoyancy and primary breathing on the same first stage.

You want a regulator that breathes easily, sits comfortably in your mouth that can be serviced reasonably. Now go and bother your LDS, try several brands, and consider paying 20% over internet best price for their help. If it's only Atomic you are being sold, consider getting a second opinion from a different dive centre.

Gerbs