Scott 2.2/ 3.5/ 4.5 Air-Pak SCBA - Valve Assembly

Valve Assembly

The valve assembly is the appliance which will make the connection between the cylinder and the hose (which will send the air to a pressure reducer). It is constructed of forged aluminum alloy, and is angled to reduce stress of the connection made between to the high pressure female coupling of the high pressure hose. Newer cylinders contain a "tri lobe, ergonomically designed hand wheel." This hand wheel is a one way, ratcheting type knob which is a push to close style knob. This protects the user from unwanted accidental shut off during use.

There is also "an upstream connected frangible disc safety relief device" located on the valve assembly which is also known as the "tri-dimensional burst disk". This burst disk protects the user against situation where the pressure in the bottle would increase with exposure to heat during a fire. It prevents unwanted failures somewhere else in the bottle. It is set to release at 7200 psi, or 400 °F. It is "tri-dimensional" in that, if it is activated, it would disperse the air from the bottle in three directions so as not to throw the user off his or her balance.
The high pressure male coupling, included in high pressure bottle connections, is set to met the Compressed Gas Association Standards #346 and #347.
Also included in the assembly are the dual sided pressure gauge (which reads the cylinder pressure directly from the cylinder), elastomeric bumper (a protective, rubber like stop), and hangar plate (for positive locking attachment of the assembly to the backframe).