3-3. Maintenance of Oral-Nasal Mask.
This task covers:
Helmet donned IAW paragraph 2-7.
Normally the diver breathes in and out of the demand regulator.
However, the valve in the side of the oral-nasal mask allows the
diver to receive air from the side block.
Test the oral-nasal mask by turning in the dial-a-breath and adjusting the steady flow valve on the
side block to allow the diver to receive air from the side block.
If air can be received through the valve, the oral-nasal mask can continue to be used.
Replace the oral-nasal mask if it fails to meet this test.