scubapro mk 18 for cold water
- Thread starter richies
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I dive with the MK18UL (Aluminum) reg in both cold and warm water. I've had no problems in 40 F degree water on a 30 minute dive. I probably wouldn't take it any colder though.
The Mk 18 is a Mk 16 with a swivel cap for the LP ports. The MK 16 draws the air for the LP ports directly off the IP chamber in the body while the MK 18 uses 3 holes in the body to route the air forward to the swivel cap. But for all intents and purposes they are functionally identical. The MK 18 is not marketed in the US for what ever reason.
The maximum flow rate of the MK 16/18 is 170 cu ft/minute compared to 300 for the MK 25, so the MK 16/18 has far less demand placed on it in terms of adibatic cooling. However the lower flow rate still good and is comparable to the flow rate of the older Mk 10 and will offer more than enough air for a diver at depth. The root cause of the MK 25's difficulty in cold water is its very high 300 cu ft/min flow rate which can potentially exceed the regs ability to deal with the adibatic cooling load under some circumstances.
Mk 16/18 also has only the teflon coated mainspring exposed to the water and has a very open ambient pressure chamber that offers a lot of relatively warm water flow to the spring. A first stage freeze up is very unlikely and the Mk 16 or 18 is a very good choice for cold water diving.
The maximum flow rate of the MK 16/18 is 170 cu ft/minute compared to 300 for the MK 25, so the MK 16/18 has far less demand placed on it in terms of adibatic cooling. However the lower flow rate still good and is comparable to the flow rate of the older Mk 10 and will offer more than enough air for a diver at depth. The root cause of the MK 25's difficulty in cold water is its very high 300 cu ft/min flow rate which can potentially exceed the regs ability to deal with the adibatic cooling load under some circumstances.
Mk 16/18 also has only the teflon coated mainspring exposed to the water and has a very open ambient pressure chamber that offers a lot of relatively warm water flow to the spring. A first stage freeze up is very unlikely and the Mk 16 or 18 is a very good choice for cold water diving.
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