Water Vapour Content and Its Effect on CABA Regulator Freeze-Up
DEFENCE AND CIVIL INST OF ENVIRONMENTAL MEDICINE DOWNSVIEW (ONTARIO)
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During the winter months the Canadian Forces CF have experienced problems with high water content levels in divers compressed breathing gases. One problem investigated was the validity of the standard used to specify water content levels. The standard suggests that water is a contaminant in the compressed gas because it might cause freezing of the breathing apparatus regulators. Present thinking disagrees with this suggestion consequently, an experiment was performed in which 4 diving regulators used by the Canadian Forces were tested in -.10 to 0.0 C salt water. Two conditions were tested. The first used compressed air saturated with moisture at 3000 psig. The second used ari at 3000 psig with no more than 5 millilitres per cubic metre mLcubic m by volume water content. The protocol created freeze-up conditions by activating the second stage purge button for 5 s, stopping for 5 s and then repeating this cycle until 1500 psig remained in the supply cylinder. Only one of the regulators did not free-flow in either condition however, no free-flows were attributed to ice. Instead, material performance under cold conditions was blamed. Therefore, it was recommended that the CF standard be revised to remove water vapour as a cause of compressed air breathing apparatus regulator freeze-up.
- Life Support Systems