Posted by Bob3 on February 22, 2002 at 10:50:26:
In Reply to: Why do regs freeze posted by maxell on February 22, 2002 at 10:39:29:
Here's the text on a little write-up I did on regulator freeze:
There's no set temperature where regulator freezes occur; the colder the water, the more likely it is to
happen. Some manufacturers use 40º F (4½º C) as an arbitrary number to define conditions where icing
may possibly commence.
Both saltwater AND freshwater can get down to 28º F (-2.2º C) and not turn solid if kept moving, such
as in a heavy surge or current.
The most common type of regulator freeze-up is the first stage. Unless you're using an environmentally
sealed reg, there is water inside your first stage. That water freezes from the air absorbing heat upon
expanding (compliments of the same set of physical laws that make your referigerator work).
The result is overpressurization of the second stage, resulting in a free flow. Most folks THINK their
second stage is frozen up, but it's actually the first stage that causes the second to malfunction.
Second stages do freeze up, tho mostly on the surface from breathing in them when air temp, wind chill,
etc is below freezing. Simple solution: Don't stick the reg in your mouth until you're underwater.
The other type of second stage freeze is much more rare, in that the water temp almost always has to
be below freezing & you have ice build up inside the regulator from breath condensation.
This can happen to even the BEST freeze-proof regulator if the conditions are right.
Hint... double hose regulators don't have this problem. To date, the most all-around freeze-proof reg is
still the double hose.
Tip for folks using a separate bottle for drysuit inflation: Install a pop off (overpressure) valve on an LP
port of the regulator. In the event of freezing, you won't have to worry about having a hose blow (or the
valve on your suit explode).
Out here in CA the water temps aren't cold enough to make freezups much of a problem at all.