The Navy’s Extreme Cold Water Regulator Tests

During the past couple of years, the U.S. Navy has evaluated several commercially available regulators in 28 degree F seawater, down to depths to 198 feet. Here’s what they found:

Poseidon Odin Jetstream: Under these rigorous conditions, the probability of failure was very low and there were no high breathing pressure incidents with a 1500 psi supply pressure. It is recommended for Navy use in sea water down to 28 deg F and depths to 190 fsw.

Scubapro MKlO and MK2O: The probability of failure for the Scubapro MK2O was relatively high, but was lower than in the MKlO. There were several high breathing pressure events in both regulators at a 1500 psi supply pressure. Performance was improved at 500 psi supply pressures. Neither the Scubapro MKlO nor the MK2O is recommended for Navy use in seawater down to 28 deg F and depths to 190 fsw.

Sherwood Blizzard and Sherwood Maximus: The probability of failure for the Sherwood Blizzard was approximately half that of the Maximus. Furthermore, the Blizzard’s breathing effort was consistently lower than the Maximus, especially at low supply pressures. The Sherwood Blizzard should be adequate for dives of up to 40 minutes in sea water temperature to 28F. Deeper than 100 few, only moderate work should be accomplished.

U.S. Divers Nordic: There were no freeze-ups of the first or second stages, however resistive effort was remarkably high, especially at low tank pressures. The first stage regulator frequently malfunctioned due to the loss of silicon oil. It is not recommended for Navy use in cold water down to 28F at any depth.