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Centrifugal Fire Pump Selection Criteria according to NFPA 20

Centrifugal Fire Pump Selection Criteria

Centrifugal Fire Pump Selection Criteria

Centrifugal Fire Pump Selection Criteria


Definition of centrifugal pump.

According to NFPA 20 - 2019 edition, centrifugal pumps are defined as pumps in which the pressure is developed principally by the action of centrifugal force.


Centrifugal firefighting pump types.

Several types of centrifugal firefighting pumps are available to be used in the field of fire protection like: end-suction, horizontal split case, vertical inline, and etc.

Centrifugal fire fighting pump selection criteria:

  • The greatest single demand for any fire protection system connected to the pump is less than or equal to 150% of the rated flow of the pump.
  • Shutoff head shall be less than or equal 140% of rated head.
  • At 150% of rated capacity, head shall not be less than 65% of rated head.

Note that: The performance of the pump when applied at capacities over 140% of rated capacity can be adversely affected by the suction conditions. Application of the pump at capacities less than 90% of the rated capacity is not recommended.


Note that:  The selection and application of the fire pump should not be confused with pump operating conditions. With proper suction conditions, the pump can operate at any point on its characteristic curve from shutoff to 150% of its rated capacity.

Centrifugal Pump Capacities:

    Centrifugal fire pumps shall have one of these rated capacities (25, 50, 100, 150, 200, 250, 300, 400, 450, 500, 750, 1000, 1250, 1500, 2000, 2500, 3000, 3500, 4000, 4500, or 5000 gpm) and shall be rated at net pressures of 40 psi (2.7 bar) or more.

Can we use centrifugal pumps over 5000 gpm?

Yes, but it shall be subject to individual review by either the authority having jurisdiction or a listing laboratory.


References of this article:

- NFPA 20 - 2019 edition (Standard for the Installation of Stationary Pumps For Fire Protection).


For more information about fire fighting pumps, please visit the topics in links below:






Fire Protection Specialists
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3 comments:

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  2. Dear Sir,

    Please advise. Let say, our hydrailic calculation stated the fire pump only need rated capacity at 600 Gpm. Is it mandatory to follow the stated capacity in the nfpa 20, so we have to use 750 Gpm. Or we can keep sizing the pump as per our requirement.

    Thanks,
    FR

    ReplyDelete