Someone's Article on Environmental Sealing

[Luis H]

Hint... double hose regulators don't have this problem. To date, the most all-around freeze-proof reg is still the double hose.

That should not be a surprise since double hose regulators are the only regulators that both the first and second stage are environmentally sealed. This is accomplished with out any complicated liquid filled chambers or mechanical pressure transferring devices. Actually there mechanism are so simple and reliable that in the case of the Royal Aqua Master several single hose regulators have copied its internal components (Conshelf, Titan, etc.).

The mechanisms from both the first and second stages are always dry, never directly exposed to water, particles suspended in the water, or even the moisture from you exhaled air.

GUE did a bunch of dives on the Britannic in 1999 and knowing how anal they are about equipment I would almost bet money that they used sealed apex or scubapro first stages to 400fsw+ without a problem.

Oh and just an interesting observation, long before the GUE divers decided to dive the Britannic, Cousteau and his team dove it a number of times and did one of his TV specials on it. They were all using double hose regulators; I believe they were Spirotechnique Royal Mistral.



What the article mentions about the overpressure first stage could cause a free-flow at extreme depths is probably true, unless the design of second stages are pneumatically balanced.