Changes to NFPA #20 for 1996 Edition

Standard for Installation of Centrifugal Fire Pumps

 

NFPA 20 changed in 1996 because of actions taken at the annual meeting held in Boston in May. As a matter interest, NFPA 20 will be expanding its scope to include other than centrifugal pumps such as positive displacement pumps (e.g., foam proportioning pumps and water mist system pumps).

 

The Following details the major changes to NFPA 20.

1.

The rules on suction piping have been modified to permit the inclusion of check valves, backflow preventers, and even butterfly valves under certain conditions in the fire pump suction piping arrangement. Section 2-9.9

2.

Eliminated the requirement for relief valve on adjustable-speed drivers Section 2-13.1

3.

Eliminated the exception that permitted the piping of the relief valve back to the suction piping. Chapter 2-13.6

4.

Recognized welding of the suction and discharge piping within the pump room according to NFPA 51B Chapter 2-8.4

5.

Permits gauge pressure at the suction flange to drop to -3 psig where the water supply is a suction tank at or above the elevation of the pump. Chapter 2-9.3

6.

Chapter 5 on High Rises has been deleted in recognition of the pump requirements being addressed elsewhere in the standard.

7.

All of the electrical installation requirements have been transferred to NFPA 70, the National Electrical Code. NFPA 20 will retain the electrical performance criteria such as what determines a reliable electrical power supply, etc. Chapter 6-3.2.2

8.

Ventilation requirements are to be provided to limit maximum combustion air intake (pump room) temperature to 120 degrees F at rated load. Chapter 8-3.2

9.

The size limits on Vertical in -Line and end suction pumps have been eliminated. Previously, these pumps were limited to 750 GPM and 500 GPM, respectively. Chapter 3-1 and 3-1.1

10.

Chapter 2-9.1 more clearly defines suction pipe and fittings and how far back to the water supply ins now addressed by NFPA 20.

11.

The requirement for sizing suction pipe has drastically changed. There is now a two-step determination for sizing suction pipe: within 10 pipe diameters of the suction flange, the pipe size shall be in accordance with Table 2-20; and beyond 10 pipe diameters, the size of the pipe must be such that the velocity does not exceed 15 feet per second at 150% of rated capacity. Chapter 2-9.3

12.

NFPA 20 now covers controllers for foam pumps in a new section. Chapter 7-9

13.

NFPA 20 now provides details for radiator cooled diesel engines, along with changes to the requirements for diesel engines and their installation. Chapter 8-2.6.6