Chapter 2
Cylinder and Components
56 SAFETY FIRST Edition 1 – December 2019
MSA G1 Electronic Breathing Apparatus
Demand valve
The demand valve connects to the facemask via a fixed position push-to-connect
connection and supplies air on demand, via a first breath mechanism. It maintains a
positive pressure in the facemask while the BA is in use.
The demand valve:
is connected to the facemask via a fixed position push-to-connect (PTC) connection;
is disconnected from the facemask by simultaneously pressing the top and bottom
buttons;
has light ports that provide the light to the face mask HUD.
The demand valve provides breathable air to the operator. It reduces the medium
pressure to 4.2 millibar above atmospheric pressure.
The PURGE button, located on the front of the demand valve, allows operators to
activate the demand valve manually to provide a quick burst of air during use.
The PARK button (red button) on the bottom of the demand valve is used to place the
BA in PARK.
Pressing the PURGE button while the demand valve is
not
connected to the face mask
will result in air flowing continuously until the PARK button is pressed.
The demand valve is indexed to the face mask, which means it can only be inserted
one way; that is, grey button at the top, red button at the bottom.
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