According to NFPA code 24, chapter 5.6: "A single automatically controlled fire pump installed in accordance with NFPA 20 shall be an acceptable water supply source.", The NFPA code requires just one pump. Maintenance "without delay" is required of course when necessary. More...
According to NFPA 20 Standard for Stationairy Pumps for fire protection Chapter (6, Centrifugal pumps) 6.3.4.1 :"Pumps that require removal of the driver to remove rocks or debris from the pump impeller shall have a pipeline strainer installed in the suction line a minimum of 10 pipe...