Pre-Use And Monthly Checks; General; Pneumatics; Demand Valve - Scott Sigma 2 User Manual

SIGMA 2
3. PRE-USE AND
MONTHLY CHECKS
3.1

GENERAL

1. Check that all parts are clean and
undamaged.
2. Ensure that the shoulder harness is
fully slackened and that a fully charged
cylinder is securely attached to the back-
plate. Replace discharged cylinders.
3. Check that the harness slides freely
through buckles.
4. Check that the facemask visor is
clear and free from marks and damage that
might impair vision. Fully slacken head-
harness straps.
5. Apparatus that fails any of these
checks must be serviced in accordance
with the SIGMA 2 Service Manual.
3.2

PNEUMATICS

1. Check cylinder connector O-ring is
clean and undamaged.
2. Screw hand-wheel connector firmly
into the cylinder valve outlet.
3. Check that pressure gauge, whistle
and hoses are in good condition and are
not kinked or stretched.
3.3

DEMAND VALVE

1. Check that the DV O-ring is clean and
undamaged.
2. Fit the DV to the facemask and check
that the locking catch clicks into place.
Gently twist the DV to ensure that it is
securely fitted.
3. Check that the bypass valve is closed
(flat area on knob is toward the face-piece).
4. On first breath DVs only, press the
black reset button.
3.4

CHECK FACEMASK

1. Don the facemask (see Section 4.2).
2. Open the cylinder valve and check
that the cylinder is full.
3. Check that the facemask pressurises.
If necessary adjust the mask to obtain a
leak tight fit. DO NOT over-tighten the
harness as this distorts the mask.
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