Procedures are the same for either the dry chemical or AFFF system.
Close cylinder valve if open
Turn cylinder valve hand wheel (1) (fig. 4-3) fully counterclockwise (open).
Close (lower) quick release lever (2) and rotate cross shaft (3) until flat is horizontal
Turn hand wheel (1) fully clockwise (closed).
Figure 4-3. Cylinder Valves
Relieve system pressure (a) Remove strip tie (1) (fig. 4-4).
Pull retaining clip (2).
Open ball valve (3).
Squeeze fire hose nozzle valve lever (1) (fig 4-5) to relieve system pressure.
Close ball valve (3) (fig 4-4)
Install retaining clip (2) over ball valve (3) handle.
Install new strip tie (1).