Water Demand Formula for Fire Fighting – Environmental Engineering

Water Demand Formula for Fire Fighting – Environmental Engineering

 

FIRE DEMAND FORMULA

Water required for fire fighting is usually known as fire demand . Rate of fire demand is treated as a function of population and is worked out on the basis of empirical formula as follow-

1. Kuichling Formula

 

where ,

Q = Amount of water required in liters/minute

P = Population in thousand

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2. Freeman Formula

 

where

Q = Amount of water required in liters/minute

P = Population in thousand

F = number of simultaneous fire streams

3. National Board of Fire Under Writers Formula

(A) For Central Congested High Valued City

(1) Where Population < 200000

(2) Where Population > 200000

For First Fire(lit/minute)     For Second Fire(lit/minute) Q=9100 to 36400

(B) For Residential City

No.	Type of Building	Amount of Water Required (Q)
1.	Small or Low Buildings	Q=2200 lit/minute
2.	Larger or higher buildings	Q=4500 lit/minute
3.	Apartment, High Value Residences,Tenements	Q=7650 to 13500  lit/minute
4.	Three Storeyed Buildings in Density Builtup Sections	Q=27000 lit/minute

 

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4. Buston’s Formula

 

where

Q = Amount of water required in liters/minute

P = Population in thousand

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5.  Frequency of fire may occur

The above formulae for water demand donot take into account the frequency of fire may occur.It may be determined from the following expression :-

 

where

t = Duration of fire in minutes

T =Period of occurance of fire in years

Note:- The recommended minimum values for the above formula are t=30minutes, T = 1 year