Atomic vs SP...yea i know...

[DA Aquamaster]

The mk17 is a fine regulator, I trained on them. However I believe the rational behind people wanting more metal arts over plastic is due to the comparatively high specific heat of plastic and the greater heat capacity of metal. The plastic will cool much faster than metal and promote ice formation. This might be particularly important on say...an inlet tube, which is in direct contact with the expanding air.

Metal is also stronger than plastic, but i think this is a moot point in its application in regulators.

At any rate I don't think the specific heat issue will matter much until you are on the very cusp of what the regulator is capable of. I for one will never dive in water below 45...probably never 50, so i personally don't care.

I agree that more metal improves heat transfer - but that is really a second stage issue, not an internal first stage issue.

For example, you want a second stage with a metal air barrel with the metal ends exposed to open water (like the G250 or G250V with both a metal adjustment knob on one end of the metal air barrel and a splined metal nut on the inlet side of the air barrel.) as opposed to the all plastic G250HP or S600.

But...a plastic part inside the first stage (like the end of the seat carrier or the plastic disc covering the diaphragm pin pad) has nothing to do with heat transfer and if anything helps keep some of the outer parts from getting colder.

So again, metal would do nothing to improve the performance of the reg in those particular parts.

 

[JDMerk]

But...a plastic part inside the first stage (like the end of the seat carrier or the plastic disc covering the diaphragm pin pad) has nothing to do with heat transfer and if anything helps keep some of the outer parts from getting colder.

I think you kindof proved my point in this statement, the whole proposed benefit of metal in a regulator is that it promotes the radiation of cold outward...or more specifically heat inwards. Plastic as an insulator would do just as you say..."it would help keep the outer parts from getting colder"... which thermally isolates the inside parts...which is bad.

In addition i think it is wrong to say that the second stage plays more of a role in preventing ice buildup or that it is more vulnerable to ice. I mean think about it from a physics point of view.

In the first stage you are taking a gas from as much as 3500psi to anywhere between 145 to 125psi...max drop 3375

~vs~

The second stage where you are taking a gas from 145 to 125psi to ambient pressure, on the surface your looking at 14.7...a max drop of 130.3psi


I think its pretty easy to conclude that there is more heat energy being transferred in the first stage (3375psi drop) as opposed to the second stage (130.3 drop), and as such the first stage would be more amenable to ice buildup...all things being equal.

 

[lowridersvt]

I own 4 atomic m1's and a z2 all sealed

I have had my m1's dow to 200ft in 33 deg water with no issues

I also own a mk17/g250v that is not bad i have had it deep it seems to get worse breathing than the atomics past 130ft even with trimix . the hose routing sucks for even a singles rig so now it lives on my 02 bottle . I also have a mk14 that i use as a argon reg

The mk25 are definatly not a cold water reg even on a 70ft bottle they like to freeflow in anything colder than 50 deg

 

[T-race]

This thread caught my attention, because I'm looking at buying gear for the first time, and am considering a well-cared for 2005 Atomic M1. It has a custom clear (small) mouthpiece (female -owned) which is good, but I noticed when I put it in my mouth, the plastic box below hit me in the chin. With the "ATOMIC" logo in raised letters, it was uncomfortable and I could imagine getting chafed. Anyone have this issue? Will I notice it underwater? Any other comments about buying a 2005 M1?

Thanks.

 

[Web Monkey]

This thread caught my attention, because I'm looking at buying gear for the first time, and am considering a well-cared for 2005 Atomic M1. It has a custom clear (small) mouthpiece (female -owned) which is good, but I noticed when I put it in my mouth, the plastic box below hit me in the chin. With the "ATOMIC" logo in raised letters, it was uncomfortable and I could imagine getting chafed. Anyone have this issue? Will I notice it underwater? Any other comments about buying a 2005 M1?Thanks.

You almost certainly have a custom mouthpiece. It's probably a SeaCure, which is excellent, although it won't fit you because it's molded to fit the owner.

The reg should not hit you anywhere. Buy a new mouthpiece. The Atomic mouthpiece is excellent if you have a normal bite, and the SeaCure (a new one) is excellent if you don't.

It's an excellent reg and I'd buy a used M1 in a heartbeat. Unless it was soaked in saltwater and buried in the backyard for years, it's probably in great condition. You'll need to get it serviced anyway (when you buy it and then every 2 years).

Terry

 

[fireflock]

^ I agree. That isn't the regular mouthpiece. Switching the mouthpiece should be $15 or less and it is easy to replace (a zip tie).

 

[Couv]

T-Race,

Welcome to Scuba Board.

I think you can actually re-form a SeaCure mouthpiece.
Seacure - Custom Mouthpiece

couv

 

[Web Monkey]

T-Race,

Welcome to Scuba Board.

I think you can actually re-form a SeaCure mouthpiece.
Seacure - Custom Mouthpiece

couv

It will sort-of re-form, but I've never been able to get mine to do anything impressive. It just softens up and the bumps sort-of flatten out a little. It never seems to recover it's original thickness.

In any case, mouthpieces are cheap. I wouldn't be in a big hurry to use someone else's custom mouthpiece on a regular basis.

Terry

 

[Katamuki]

My wife uses a Mk17 but complains when she goes below 80 ft that the inhalation draw required is a bit noticeable, this is with the S555 2nd stage. This week I switched an Atomic T2 2nd to see if this will fix it. She has done 9 dives so far with this combo and says that it is a little better and the adjustability is a nice feature. I tried to get her to use an Atomic B2 reg I have but the piston makes some serious noise when breathing heavy and this didnt appeal to her. My goal is to switch her into a spare AL Legend reg kit I have on Friday for her final comparison and I believe this will be the reg she ends up with, the AL Legends breath very very well at depth and the draw characteristics are fairly uniform throughout all depths.

Yesteday, Mk17 1st stage, Atomic 2nd stage

 

[Marcin2005]

I recently switched to the MK17/G250V combo (from MR22/Abyss) and must say that from my experience the perceived ease of breathing has more to do with the tuning of the second stage than anything else. It appears that the regs come somewhat de-tuned from the factory. I paired mine with a D400 took it down to about 95 ft in the St Lawrence River and the good old D400 was an easier breather. Mind you due to a very strong current D400 had a tendency to "burp" some air where as G2500V stayed "quiet".