VISION 3
7
2.
Tighten harness side straps. DO
NOT over-tighten.
4.2.3
All Facemasks
Inhale deeply to activate the DV and then
breathe normally.
4.3 POSITIVE PRESSURE
TEST
With the cylinder valve open, insert a
finger under faceseal and check for a
steady outward flow of air. Remove finger
and allow mask to re-seal.
4.4 FACEMASK SEAL TEST
1.
Close the cylinder valve and keep
hold of the handwheel. Hold breath for 10
seconds and listen carefully for leaks. A
leak will cause the pressure gauge
reading to fall.
2.
If the facemask fails the leak test:
open the cylinder valve, loosen the head-
harness, adjust the facemask and repeat
the test.
4.5 BYPASS TEST
Turn on the DV bypass knob and check
for a steady flow of air into the mask,
then close the bypass.
