Typical Fire Water System NFPA20.

The entire fire water package shall be NFPA20 2022 compliant. Deviations from NFPA20 require written acceptance from the AHJ (per 3.2.2). If available all equipment shall be listed UL and/or FM. In addition, the package shall be designed and built by a listed fire pump manufacturer and the entire assembly shall be ETL listed for fire pump service. 4.31.1(3). Units are to be located in a pump room in accordance with NFPA20 unless otherwise specified by the AHJ. (per 7.4.2)

Fire water system with three main pumps. Additional main pumps may be added or the number of pumps may be reduced according to pump size limitation and system size. It is recommended one or more of the main pump(s) is/are diesel engine driven. Tanks may be replaced with large volume water supply (pond, river, etc). Circulation relief valves (to provide cooling for main pump during no flow conditions) shall be sized, installed and discharge to visible drain according to NFPA-21 4.11.

Pressure relief valves may be required for diesel engine driven pumps according to NFPA-20 4.18

Pressure relief valves shall discharge back to source of supply. The spare jockey pump and associated min flow orifice may be eliminated if other reliable compatible water source is available and has acceptable stable pressure. For additional information see NFPA-20 Fig A4.20.1.2 (a).