Your Questions about Closed Circuit Rebreather (CCR) diving answered.

[rjack321]

Disagree, but mainly just a semantic thing.

Saying that you have been doing something for 20 years without incident, especially a senior person saying that in a public form, has implications for new divers, who may take home the message that it's safe.

Nobody said diving with active heat was 100% safe. It took ten years after some of us early adopters started playing with heat (my first vest circa 2007-8 was homemade from 'waterproof' snowmobile seat pads) before we learned that warm at the beginning and cold at the end (due to heat failing or battery depletion) is definitively associated with DCS. We have also since learned that the iron based hand warmers are a terrible idea with nitrox due to the elevated ppO2s. And that its at least possible (although exceptionally rare) to have electric heat combust enough to actually melt a drysuit. These are knowledge gaps which are being filled over time.

 

[doctormike]

Nobody said diving with active heat was 100% safe.

Agree. Nobody said that.

 

[wedivebc]

Disagree, but mainly just a semantic thing.

Saying that you have been doing something for 20 years without incident, especially a senior person saying that in a public form, has implications for new divers, who may take home the message that it's safe.

As I said earlier fire requires three components. Using a high oxygen mixture in a suit has no risk if there is no heat source. For combustion to occur the fuel must be raised to it's flash point which is a temperature at which it releases flammable vapour then that mixture needs to be exposed to it's ignition temperature. No amount of static electricity inside a suit will meet these requirement. The previous analogy with acetylene is not relevant because there is no flammable gas present inside a drysuit. I stated that I had not heard of any accidents involving high O2 inflation gas and not withstanding those caused by an outside source I still believe there is no risk of autoignition in a drysuit.

 

[Dusty123]

i mean what if you ate a ribeye last night with a few beers

 

[Dusty123]

jalapeno poppers for appetizer?

 

[rjack321]

As I said earlier fire requires three components. Using a high oxygen mixture in a suit has no risk if there is no heat source. For combustion to occur the fuel must be raised to it's flash point which is a temperature at which it releases flammable vapour then that mixture needs to be exposed to it's ignition temperature. No amount of static electricity inside a suit will meet these requirement. The previous analogy with acetylene is not relevant because there is no flammable gas present inside a drysuit. I stated that I had not heard of any accidents involving high O2 inflation gas and not withstanding those caused by an outside source I still believe there is no risk of autoignition in a drysuit.

Agree, but there are a lot of people diving heated vests nowadays - and its the worst idea to have batteries inside the suit and inflate with a high ppO2 gas