Chapter 2
Cylinder and Components
32
SAFETY FIRS T
Edition 1 – December 2019
MSA G1 Classic Breathing Apparatus
Sizes
The facemask is available in three sizes: small, medium and large.
Sizes can be identified by looking at the side of the facemask and locating an
S, M, or L.
Another way to identify the facemask size is by the tabs on the facemask buckles.
Small is designated green, medium is black and large is grey
Figure 21–
facemask head harness
The BA set is issued with a medium sized mask as the standard.
A facemask fit test can determine the correct size for the operator. Please contact the
State PPE&C Management Centre for information regarding
Facemask Fitment
Procedure
.
Pressure gauge
The pressure gauge provides the operator with an accurate reading of how much
pressure (in bar) is left in the cylinder.
The glow-in-the-dark pressure gauge is a bourdon tube pressure gauge which works
by having
a curved flattened tube behind the display of the gauge. As the tube is
pressurised it wants to straighten, thus allowing an accurate measurement of the
pressure in the cylinder.
The pressure gauge incorporates an egress flap on the rear of the gauge. This egress
flap is a small rubber disk that is glued onto the rear of the gauge and designed to
release if the pressure becomes slightly elevated within the gauge casing. As there is
little to no resistance from this egress flap, it will release before any additional damage
is done to the gauge.
