NAC455C.282. Pressure-reducing valves.

     1. Where pressure-reducing valves are used, at least one relief or safety valve must be provided on the low-pressure side of the reducing valve if the piping or equipment on the low-pressure side does not meet the requirements for the full initial pressure. The relief or safety valve must be located downstream and as close as possible to the reducing valve. Proper protection must be provided to prevent injury or damage caused by any fluid escaping from the discharge or relief or safety valve if vented to the atmosphere. The combined discharged capacity of the relief or safety valve must be such that the pressure rating of the lower pressure piping or equipment is not exceeded if the reducing valve fails when it is in the open position.

     2. Hand-controlled bypasses around reducing valves may be used. If a bypass is used around the reducing valve, the safety valve on the low-pressure side must be of sufficient capacity to relieve all the fluid that can pass through the bypass without overpressuring the low-pressure side. A pressure gauge must be installed on the low-pressure side of a reducing valve downstream of the safety relief valve.

     (Added to NAC by Div. of Industrial Relations by R101-02, eff. 12-15-2004)