How do ice kits work?

[SparticleBrane]

I searched for this and couldn't find anything, hopefully this isn't a double post.


I recently bought a DiveRite RG2500 reg system with the ice kit preinstalled. I do some quarry diving locally and sometimes it's quite cold (not to mention silty). I get the idea of having an "environmentally sealed" first stage (ie: Apeks DS4) so that things don't freeze, but I'm curious as to how the ice kit works.

As clarification, I'm not looking for "it keeps ice from forming." I'm looking for a more technical answer...ie does it seal the reg, or what?


Thanks!

 

[DA Aquamaster]

I am not sure on the Dive-rite kit, but in general there are three types of seal kits on diaphragm first stages.

1. The ambient chamber may be filled with silicone oil contained by a diaphragm.
2. The ambient chamber may be filled with alcohol contained by a diaphragm.
3. The ambient chamber may be air filled and sealed with a diaphragm (which requires much more sophisticated engineering).

 

[cmufieldhockey8]

I think I remember being told it seals it for the Dive Rites. I may be mistaken.

 

[utnapistim]

As far as I know diaphragm first stages have a (latex?) diaphragm that has water on one side and the air chamber on the other side;

I'm not familiar with your first stage and environmental seal models, but here is my understanding of what goes on inthere (anyone who knows more, please correct this ):

When the air pressure drops (due to you inhaling) the water pushes the diaphragm which in turn pushes a valve letting more air out of the tank, which will make air pressure raise and cause the diaphragm to drop back in place (and not let more air in until your next breath).

When air comes from the tank to the first stage, it goes through a steep drop from the tank pressure to the first stage pressure (around 10 bar, depending on the model I think); this in turn will cause the air to drop a few degrees in temperature (it's the same principle ice boxes use to keep my food cold);

If you don't have an environmental seal in place, that drop in pressure may be enough to cause any water particles entering the first stage to form crystals which will get you a frozen first stage.

The purpose of the seal would then be to stop water particles from getting into the first stage at all.

I think freeze is also prevented by having a good heat-transfer system in place: this will help transfer heat from the water to the air as fast as possible. The heat transfer takes place even if the water is a few degrees over freezing point, and it may be enough to keep ice from forming.

 

[ProfessorAronnax]

This isn't extremely technical but has some decent info: Zeagle Regulator Environmental Sealing

 

[rescuediver009]

Diaphragm regs all protect the moving components (hp seat & spring). That is why they are the tendency of most coldwater divers.

The balancing of a diaphragm first stage comes from the water pressure exerted on the external side of the diaphragm. All that the environmental seal does is fill the space where the balancing spring is with a liquid that does not freeze at 32 deg. The liquid acts as a load transmitter to transmit the water pressure onto the diaphragm, thus balancing the reg. The dry seal (a la apeks) uses a load transmitter piston to transmit the load onto the primary diaphragm. This dry system is favoured by divers and service techs alike since it is alot let messy and easy to service. I believe that this is also the same system that dive rite uses.

For a better diagram check out the Apeks DST first stage that is very much like the dive rite: http://apeks.co.uk/home_frameset.htm