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Discussion of diving methods and equipment available prior to the development of BCDs beyond the horse collar. This forum is dedicated to the pre-1970 diving.
Eric S
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Nitrox and double hoses

Mon Dec 28, 2009 7:48 pm

Any problem running 32% or 36% through a DA?
I can't think of any, but I just want to make sure.

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Bryan
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Re: Nitrox and double hoses

Mon Dec 28, 2009 8:04 pm

Not even remotely...
Doing it right should include some common sense, not just blindly following specs and instructions. .Gary D, AWAP on SB

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Ron
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Re: Nitrox and double hoses

Mon Dec 28, 2009 8:34 pm

PTFE, or polytetrafluoroethylene, sold by the trade name Teflon, does not react with oxygen. DA seats are either PTFE or plain old nylon, neither of which react with oxygen. There are no rubber o-rings in the high pressure side of a DA, and only one in the HP side of a RAM (which you can replace with a Viton one if you feel so inclined). Rubber is perfectly safe in the low pressure sides of virtually all regulators, as that side only sees intermediate pressures. The Atomic rebuild kits that I used to install only had Viton in the "wet" or HP side, the rest were all regular old 70 durometer buna rubber.

Let me know if you need any Viton o-rings before you run out and place a minimum order. I have enough to last me until I die, and I'm only 30 so you can have a few if you need some should you decide you want them for a RAM or future projects. The DA series is fine as is though. I don't know that I personally would cover your gear in non-oxygen compatible grease and then crank 40% nitrox through it, but I just use tribolube on everything anyway because I think it is a cleaner build.

YMMV, but I guess the short answer is what Bryan just said. I've had a lot of caffeine today so my ADD and PTSD are competing :lol: :shock:
The impossible missions are the only ones which succeed. -JYC

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Gilldiver
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Re: Nitrox and double hoses

Tue Dec 29, 2009 9:37 am

All of my double hoses can see NITROX at any time. A few of them have seen 21/25-21/35 tri-mix at times, I'm still here.

In other words, what Bryan said.

Pete
Double Hose Regulators, It not just a Hobby, it’s a Disease

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Bryan
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Re: Nitrox and double hoses

Tue Dec 29, 2009 9:52 am

I took my Oxygen / Acetylene regulator and hoses off my torch set from the shop to my LDS for proper cleaning :roll:
Doing it right should include some common sense, not just blindly following specs and instructions. .Gary D, AWAP on SB

swimjim
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Re: Nitrox and double hoses

Tue Dec 29, 2009 11:28 am

Bryan wrote:I took my Oxygen / Acetylene regulator and hoses off my torch set from the shop to my LDS for proper cleaning :roll:
Or did the static electricity from that bread bag you were inflating touch it off and clear your sinuses? LOL Oxy/Acetylene, great fun. I hear you can even use it for welding :shock:

Tahoeguy
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Re: Nitrox and double hoses

Tue Dec 29, 2009 9:38 pm

No problem, I do it all the time. Here in Lake Tahoe and in the Ocean, however, nothing richer than 40%. None of my DH's are O2 clean.

Eric S
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Re: Nitrox and double hoses

Tue Dec 29, 2009 11:28 pm

I just didn't know if any higher levels of O2 would expedite the breakdown of rubber hoses etc. I've replaced all the other stuff with silicone parts so I know they're fine. On the labels it says "Use compressed air only" but I figured back in the day there was no nitrox (or at least none to the general diving public) so they must have been refering to pure O2.

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Ron
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Re: Nitrox and double hoses

Tue Dec 29, 2009 11:44 pm

If you want to get technical, supposedly buna rubber o-rings degrade at an accelerated rate when exposed to higher concentrations of oxygen at high pressures. If you want piece of mind you can run Viton o-rings, but a DA doesn't have any in the HP side so that would leave Viton o-rings for a RAM/PRAM, etc.
The impossible missions are the only ones which succeed. -JYC

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luis
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Re: Nitrox and double hoses

Wed Dec 30, 2009 7:05 am

Eric S wrote:I just didn't know if any higher levels of O2 would expedite the breakdown of rubber hoses etc. I've replaced all the other stuff with silicone parts so I know they're fine. On the labels it says "Use compressed air only" but I figured back in the day there was no nitrox (or at least none to the general diving public) so they must have been refering to pure O2.

The reason for the label was because at one time it was easier to obtain compressed O2 than compressed air. The concern was not with the regulator, but with oxygen toxicity for the diver.

All regulators can handle Nitrox up to 40%. For higher O2 is when any regulator needs to be O2 cleaned and properly lubed.

A properly service Aqua Master, RAM or PRAM can handle Nitrox. Again if you are using high O2 (> 40%), it should be O2 cleaned.

I have many dives on my PRAM with Nitrox.


Slonda
The issue with using Viton instead of Buna-N is more of an issue for tank O-rings that are exposed to the compressed gas for 24 hours a day. A regulator that is only used for a few hours a week can use Buna-N with high O2 concentrations and the O-rings should still last years.

Pure oxygen is just too new to the dive industry and IMHO they are too conservative... which I guess is better to be conservative than not, in this situation.
Luis

Buceador con escafandra autónoma clásica.

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Ron
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Re: Nitrox and double hoses

Wed Dec 30, 2009 7:22 am

Well said Luis, thanks for the heads up!
The impossible missions are the only ones which succeed. -JYC

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eskimo3883
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o-rings and ice diving?

Wed Dec 30, 2009 7:14 pm

Since some of you lake divers end up in near freezing conditions is there a temperature issue that comes into play with the choice of Viton Vs. buna-N?
“A skin diver is a fellow who pulls on a pair of fancy swimming trunks, some rubber fins, a diving mask and canvas gloves, then fills his lungs with air and noses down into the ocean looking for two fisted trouble.”

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Ron
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Re: Nitrox and double hoses

Wed Dec 30, 2009 9:40 pm

Eskimo, what do you mean? All my Viton rings are the same durometer and similar temperature ranges as their buna rubber counterparts.
The impossible missions are the only ones which succeed. -JYC

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luis
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Re: Nitrox and double hoses

Wed Dec 30, 2009 10:48 pm

Both of those rubbers can operate at colder temperatures that you will ever see while ice diving. The water obviously never get too cold (normally about 34 F or a bit lower for salt water), but the air temperature could be much colder.

The normal issues is any moisture freezing, not the O-rings properties on these kind of temperatures.

According to the Parker O-ring manual:
Nitrile (Buna-N) is good to about -58F
Fluorocarbon Rubber (Viton) is only good to about -9F

I don't think I am going to be diving at either of those air temperatures.

At -9F the least of your concerns are the O-rings.
Luis

Buceador con escafandra autónoma clásica.

Scuba Cowboy
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Re: Nitrox and double hoses

Thu Dec 31, 2009 1:03 am

"At -9F the least of your concerns are the O-rings."

Now there's a quote to live by!
Dale Swift

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