1st Stage Freeze Up Prevention

[WarmWaterDiver]

Puffer,

One thing to consider is if folks are going to use elevated tank pressures, a breathing gas mosture dew point adjustment to an even lower maximum level / max dew point temperature would be in order - we've both seen posters here on 300 bar, and even 4600+ PSIG fill pressures being used. And a degree of conservatism be employed on top of that.

We're all aware of how each diver is responsible for analyzing their own gas mixtures for gas composition for the "gross" componets. The "small stuff" is apparently overlooked, even in the tech diving community largely apparently, but the devil's in the details. Water vapor is only one of the ppm level contaminants of concern after all.

Perhaps cold and / or tech water divers should consider testing their own tanks for contaminants with their own apparatus But, your fill station should be able to assist and have a vested interest in doing so I would think. We vote with our wallets for things like gasoline, motor oil, home heating, etc. so my opinion is in a free market economy life support breathing gas supply quality shouldn't be different. Maybe the fill station the SCBA cold climate folks use has a different perspective on customer complaints and customer satisfaction . . . would such a station survive a surfeit of rescue workers whose first stages froze up on the job? Are you any less of an important customer?

 

[pufferfish]

Warmwater,
Yes there are other 'details' in the ppm range in one's air but I find these are fairly well understood by divers and the folks who set the various standards. Most people can agree that no CO is best but maybe a little is ok up to a certain point.

The problem with dewpoint is there is no consensus on what is an acceptable dewpoint, and what may be acceptable and safe in Florida is not so up here with water at the freezing point. Throw on top of that atmospheric vs. pressure dewpoints, high pressure vs. low pressure tanks, etc. and all of a sudden we have many divers where the 'eyes can't see what the brain doesn't know'. We both were in that category until researching this topic further, and unfortunately most divers and fill station managers still remain in the dewpoint challenged category! This is not surprising when the people setting the standards who are supposed experts are all over the map as well. NAUI says -40F is ok, PADI mentions -50F, and the Navy -65F when in fact the science suggests that with standard high pressure tanks in water at the freezing point - 75 F or colder is where the dewpoint should be. No wonder there is so much confusion among the ranks.

Your point about SCBA, free markets, and fill station air quality is an interesting one. Freeze failures are always a safety concern amongst rescue workers especially in the northern latitudes during the winter. I know up here there have been problems with air quality from the local dive shops especially with respect to moisture levels such that most fire stations have gone 'homegrown' (different from the usual Canadian use of this term :54. In one large city there used to be a dozen or so fill stations (many were the dive shops) where the fire station SCBA guys would fill their tanks up. After concerns not only about dewpoint, but the other 'small stuff' you mention for quality control purposes they went to only four in-house megafill stations which then ship bottles out to the other fire stations. Quality control is easier with four big fill stations and the air quality is in the hands of the guys that use the air regularly. Once economy of scale is achieved one can afford to install things like inline dewpoint monitors where when the outdoor temp is -30 C it is nice to see in realtime the air you are pumping into the tank has a moisture level of -80 C. Many large cities are looking at this fill station model where bigger in-house fill stations supply a network of other stations, and which equals better air quality and fewer equipment and heath problems for the rescue workers.

 

[WarmWaterDiver]

Puffer,

I don't agree that the effects of these "other" contaminants are evidently well recognized in the scuba community. Water dew point, and its correlation with "cold" water diving, we have definitively proven and thoroughly demonstrated, has not widely been so. Even through all the certification agencies and military forces, including the "tech" agencies. I must admit I expected a bit better from ANDI as Ed Betts had an engineeering background, but it was in mechanical engineering, while mine is in chemical engineering, and I hadn't really looked at '"cold" water diving before I moved from the Gulf Coast to the Great Lakes area. The coldest water I've dove in was 58 degrees F in Canyon Lake in Texas doing my AOW in March some years ago.

Now, in the hydrocarbon processing industry (especially light hydrocarbon and natural gas processing), there are well documented and empirically demonstrated effects of forming "ice balls" in equipment above 32 degrees F due to hydrate formation - a complex of hydrocarbon, CO or CO2, and water (and if cyanides are present one gets the funky "blue ice" phenomenon). Do these constituents (other than cyanide) sound familiar ???? Is "just a little" hydrate or ice in the regulator first stage something like being a "little" pregnant, or a "little" out of breathing gas, or a "little" bent?

However, we can usually intermittently (or continuoulsy) give the hydrocarbon systems a "drink" of methanol, or selectively remove the CO/CO2 upstream of the cryogenic equipment, etc. - not options practicable for the recreational or tech scuba diver! If one examines "Grade J" air, which I have received from some fill stations (one in St. Croix - far from cold water!) one can see the differences across the board. The few such stations I have encountered all employed electric driven oil-less air compressors. Rest assured, I WILL have means of testing my own tanks for LOTS of components before I ever go "cold" water diving, but this is purely my personal decision.

Since use of compressed breathing gas systems while in an air environment MUST far more closly approach an adiabatic system than in a liquid environment (even basic OW texts talk about the magnitude of heat loss from one's body in water versus air), my thinking was the "cold climate crowd" might want to chat with their community rescue workers about synergies in objectives and common difficulties. I wonder what such workers would comment on "piston vs. diaphragm" or one brand vs. another in regulator freeze-ups in their line of work. My engineering judgement (sounds more impressive than wild-a** guess) leads me to believe it is probable the fundamentals of dry compressed breathing gas is the single most significant factor for their applications.

DA Aquamaster - since you have had Doppler come up with an appropriate quote for your tag line (which I find exceptionally fitting), could you contact Messrs. Joule and Thompson on my behalf to describe one for me to use? These fundamental laws also do not care about certifying agency, brand name, or certification level.

BTW Puffer, you were absolutely correct to hijack my post from the other thread - the posts there since mine have all missed my point(s).

Methinks we have given the diving community enough to chew on & try to digest in this thread (myself several times over - I backslid from my earlier efforts) - but feel free to PM me for further discussion!

My next diving will be in Bonaire . . .

 

[pufferfish]

Warmwater (you can call yourself honorary coldwaterdiver now)

I can't believe I actually typed a 'little bit of CO is OK'. Those who know me and the big debates we had on this issue last summer here on the board would be rolling over in their graves. Let me qualify that CO level at less than 2 ppm in coldwater and maybe 5 ppm in Cozumel in a pinch

I do carry a CO monitor but probably should get some Drager dewpoint tubes for cold water diving when I am on the road away from known sources of high quality dry air and the most recent air certificate on the wall is a year old,..ha,ha.

Other than that a good sniff test and a blast through a white teeshirt will have to be my portable analytical field lab tests.

You are right though in that it would make very good sense to get to know people in the right places at the SCBA megafill stations.

My next dives will likely be Cozumel so I can relax about the moisture levels down there with water at 80 F,..ahhhh.

 

[WarmWaterDiver]

OK, one more thing worthy of note - BTW, Draeger and their competitor Sensidyne (www.sensidyne.com) both make tubes for measuring lots more things than water vapor . . . we were just discussing a number of them. And having the correct min-max range detection tube (or more than one range handy if expected range is unknown) is quite important for accuracy of reading, especially at the lowest levels. Approriate sampling chambers can readily be made - a nifty field-expedient can be done using an empty and DRY plastic sports drink bottle whose neck fits over the tank valve top, with a small hole cut in its side, with cylinder gas valve cracked and gas slowly flowing while inserting the broken end of the tube in the hole, and can even be used by folks as over-educated as myself (the hourly workers at the petroleum refinery I started work at in Texas showed me this technique with 16 ounce soft drink bottles for things checked there when I was a newbie, but caffiene is not the friend of the diver who still has dives to do that day, so sports drink it is!).

Draeger tubes are only made to be used with Draeger sample pumps, and Sensidyne tubes can only be used with sensidyne pumps (different tube diameters, sample pump volumes, etc.). The fire & safety supply distributors are usually the channel purchases are made through in my industrial experience (maybe another good reason to get more chummy with your community rescue workers - larger volumes of anything always cost less per unit). But, with the Internet these days, you can probably just order what you want on-line for delivery to your doorstep too, but I don't know that for sure. The tubes do have expiration dates to monitor also.

Puffer, I'll keep my coldwater diving "honorary" and a "maybe before I move away from the Great Lakes" thing for now, but I appreciate your nod.

 

[Norm]

Over 90 % of my dives are in coldwater. I have seen lots of second stages freeze and a couple of first stages.
There is no such thing as a freeze-proof regulator, although many come close. A sealed piston first stage, (Sherwood or Genesis), a first stage piston or diaphragm with an environmental kit installed, (many different brands), or double-sealed diaphragm first stages, (all current Zeagles except Envoy), are all good quality, close to freeze proof, first stages. It's easy to freeze many second stages. Hit your LP inflator for about 8 seconds, bump your second stage purge for about 10 seconds, (mouthpiece upward), and you may
have a frozen second stage. (This can even happen out of the water if the air temperature is cold enough!) There are environmental second stages with different tricks going for them to help prevent freeze up: Metal second stages, plastic housings with metal inserts, Teflon coated valve parts, silicone parts, heat sinks, and heat absorbing fins, to name a few. Damp compressed air can be a culprit. High I.P. can help lead to a freeze up. Overworking a reg can lead to freeze up. There are alot flaws in alot of models out there, but the primary reason for regulator freeze up is the way the owner treats their gear before and during the dive! Some of my personal hints: Turn the valve on very slowly. Don't purge the regulator. Test breathe the reg when it's submerged, don't go crazy using your inflator (BC or drysuit). Avoid, at all costs, any unwanted freeflows - and stop them immediately if they do start! (Often immediately is too late!) These are just some things to work with. An ice diving course is an excellent way to learn about diving in a cold environment. Just doing it, (school of hard knocks), is another way. The rules of cave diving are excellent guidelines for coldwater diving, especially the one of redundancy! It's worked for me for many, many years. Just my opinons,
Norm

 

[mikerault]

All of this is great stuff! I plan on my first cold water (at least to me) within the next few months (before the algae blooms of spring reduce viz) so the water will be between freezing and 50 degrees depending on location. With a straight sherwood setup (brut or magnum second with sherwood first) how much do I need to worry about freeze up if I avoid over use of the inflator(s), free flows and try not to breeth hard? I may not be able to control the exact dew point of the air in the tank, but since these will be cold water dive locations, I can hope the dive shop will be aware of this.

Also I had some thoughts about a free flowing frozen second. I realize it isn't good for the hose but what about crimping it and breathing from your octo until the main thaws? Why don't they provide a cutoff ball valve for this type of thing in the main line hose? A quick turn and the air would be cut off then just breath through the octo until it thaws. Same thing for all that "sipping" you learn in quals for a free flowing reg, with a cutoff it would be just shut it off and use the octo.

Mike

 

[Bobby]

Most cold water freeze ups are in the first stage, if you cut off the free flow through your second stage you will either have it flow through your octo or if you blocked that off you would blow your low preassure hose. The best action in the event is to sip off the reg that is flowing and work your way back to the surface. Second stage freeze ups are very rare, get an enviorenmental seal for your first stage and that will cover 90% of cold water issues.

Bobby

 

[sandroso]

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[Norm]

IMO: There is a lot of confusion on reg freeze up, (although most of the posts here are great posts made by people I know and/or respect). Predive behavior, (and storage of equipment), has alot to do with regulator freeze up tendancies u/w. Demanding higher quantities of air from your regulator, (ie:buddy breathing, deep diving, free flow, or BC inflation while inhaling), is a major cause of freeze up due to supercooling. I have seen first and second stages freeze up, though I must say that the vast majority of regulator freezing takes place within the second stage.
Using a sealed piston first stage is a big plus. (Sherwood regs, as well as many others, are of this type)
Using a double-sealed diaphragm first stage is a big plus. (Most Zeagle regs, as well as many others are of this type)
Using second stages that are made of metal or have metal heat sinks are an excellent route to go. (Nearly all manufacturers offer something in this catagory)
Using second stages with Teflon coated parts or extensive use of silicone parts is also a plus. (Utilization of Teflon coatings are not as widely used as it once was, though most manufacturers now utilize silicone wherever possible because of increased reliablity)
Using a servo operated second stage, ("pilot valve"), second stage is a plus in the prevention of freeze up. Most of the sensitive valve is isolated from direct contact with water and is closer to the diver's (warm) breath. (Poseidon is an excellent example of this design, and there are/have been others)
Hope this helps someone,
Norm