Mailing List Archive Mailing List Archive
> > With the Poseidon Odin pilot valve gas is not expanding inside a closed or > confined space within the second stage as it is in the typical down stream > design. Any ice that forms is, therefore, outside the mechanism so that it > "throws" ice slivers but does not "jam" the mechanism. With the down stream > design ice is able to form and build within the chamber around the popet > spring and hold it open. Until this basic design "flaw" is changed all > typical down stream designs will be inferior for ice diving where the > potential for free flow is concerned and attempts at changes in materials > to solve or reduce the problem are half assed corrections of a basic design > problem at best. Look at all the so called "cold water" regulators that > reportedly > don't work reliably. > The above paragraph is correct. The lower half of the email is also correct. By design, the Odin should have a nearly impossible chance of freezing during a dive. The exceptions are: #1. Water in the tanks or first stage. The supply air should be dry, and all parts of the regulator dry before using. ANY regulator can fail if water is left in the hoses and freezes while on the surface pre dive. #2. Regulators that are soaked pre-dive. The Odin should be able to handle this, but ALL regulators really need to be above freezing, or fully dry before operation. If you freeze the Odin's 2nd stage "balloon" because it's wet and frozen, that's the operators fault. ANY regulator should not be wet and frozen pre-dive. #3. It is a good idea to have the alcohol/silicone cap installed if at all possible. This is simply so that on the surface Ice doesn't form by the mainspring. Only under the most extreme flows would ice form underwater, but if you have the cap on, it should be impossible. #4. The Odin requires that the "balloon" in the 2nd stage be in good condition. If it has a leak, it will not work properly. #5. The pilot valve needs to be kept in good condition. It also needs to be ice free pre-dive. #6. Your first stage seat and seals need to be in good shape and not leaking. If you follow these items, you will NEVER have problems with your Odin freezing. If you also take note, most of those tips should be used with EVERY regulator for cold water diving. Either way, Odin's have a far far smaller chance of free-flowing, independent of intermediate pressure differences. We dived many different regulators over the years, and not one single one performed under the ice without freezing at one time or another...except the Odin. The only time I had a problem with an Odin is on a dive when it was -10F, on the SECOND dive of the day, AFTER it had been soaked and sitting on top of the ice for 30 minutes. That was because the first stage spring cavity was full of water (we weren't using the "cap" with alcohol). I know that for everyone the Odin isn't the favorite and do-all regulator...it has some differences, but for those who dive the Great Lakes and who Ice dive, it is probably the best regulator made for the purpose. The Aga is also good, but that is very finicky when it comes to being wet internally. Very good on the first dive of the day, but after that I don't trust them deep if they're wet inside. Freeflows are probably the #1 danger for divers in our area. I've dealt with literally dozens and dozens in the past decade. It all depends on how well a person keeps his cool, and how well they planned their contingencies. At any rate....from what I read here, Chuck Boone knows what he's talking about when it comes to the Odins. Tim > > >...In fact, a buddy of mine had a poseidon second stage blow > >right off of the end of his hose due to icing. This occurred at Lake Geneva > >Wisconsin this last December on a day when the air temperature was somewhat > >below freezing. Following his dive, he left his equipment laying on the > >ground while he changed into warm clothes. When he went back to pick up his > >gear he turned his air back on. There was a bang that sounded like a gunshot > >and the regulator second stage shot off the end of the hose. It flew 30 feet > >through the air. It had been attached to a 7 foot hose that was now whipping > >around wildly. Another dive buddy was struck smartly with the hose and > >stumbled into the lake. When we sorted everything out it became apparent > what > >had happened - The regulator first stage had frozen to free flow and the > second > >stage had frozen closed. This caused the intermediate pressure in the hose > to > >rise to tank pressure, resulting in hose rupture. > > This must have been one of the pre relief valve Poseidons or > ice formed in the relief valve mechanism while sitting on the surface > after the dive just as it obviously did around the first stage spring > when he bled the second stage after shutting the gas off (I am assuming > that this was an Odin regulator - the shower head). This is an upstream > valve, always closed against IP, and only the relief valve provides > protection against the dangers of IP overpressure, as you obviously know. > When you bleed off the second stage after turning off the tank > valve you also bleed the tank pressure from the HP chamber of > the first stage into the IP chamber and hose so that you have > opened the spring loaded seat between the two. Apparently the > spring froze into this open position instantly upon the expansion of > gas from the HP chamber of the first stage while on the surface > with some water still in the spring chamber. Don't know how this could > happen if the first stage was protected with alcohol or silicone - > perhaps it was breached somehow or the first stage failed in some other > way. > I suppose one would want to clear any water from any regulator or > BCD valves and mechanisms as soon as they exit the water on ice > dives. > > I suggested that if you could move the same volume of gas with a lesser > change in pressure the chance of icing by adiabatics in the second stage > would be reduced. Though this is true, de-tuning a regulator to reduce the > intermediate pressure will be no help to an ice diver because you will also > reduce the temperature of the gas reaching the second stage by virtue of > having dropped the pressure more through the first stage. No net gain ! > > In the final analysis you are expanding gas from tank pressure to > ambient pressure with a specific and unavoidable change in temperature > of the expanding gas. You can alter the degree to which temperature > changes at certain points in the process by controlling the location and > amount of expansion but at the rates that it must be moved the gas will > carry the net effect of these temperature drops throughout the system as > a whole before there is time for the gas to absorb enough heat from the > ambient environment to make an effective and useful difference to the > diver. > > The pilot valve of the Poseidon Odin, designed by Sweeds diving in > ice water as a matter of course, strikes me as a good solution to > second stage icing problems - let it ice all it wants just so it stays > out of the mechanism of delivery. Instead of trying to deal with ice > they rendered ice a non-problem by keeping it away from the delivery > mechanism. > > > PS Just read your post that identifies the first stage as a Sherwood but I'm > posting this as is anyway. > > > Chuck Boone > > -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
Navigate by Author:
[Previous]
[Next]
[Author Search Index]
Navigate by Subject:
[Previous]
[Next]
[Subject Search Index]
[Send Reply] [Send Message with New Topic]
[Search Selection] [Mailing List Home] [Home]