Construction Line. fire fighting system

# how to select fire pump

Selecting Fire Pumps

The following is a simple six-step procedure for selecting a fire pump:

1. Perform the hydraulic calculations of the fire protection system from the most remote portion of the system to the place where the discharge fl**ge of the pump will be located.

2. Calculate the suction pressure at churn (no flow) and the flow demand of the fire protection system by taking the residual pressure at the water supply and subtracting the friction loss between the water supply and the pump. Also, take into account the elevation change between the water supply and the pump.

Note that for this calculation, the suction pressure at churn should be calculated using the highest consistent pressure from the water supply. The suction pressure at the system flow demand should be calculated using the lowest reasonable residual pressure from the water supply, taking into account daily and seasonal fluctuations.

3. Select a model of a fire pump to consider where the flow demand of the fire protection system is less than or equal to 150 percent of the rated flow of the pump.

4. Using the manufacturer’s performance curve for the model of fire pump you want to use, determine the net pressure from the pump at churn (no flow) and the demand flow of the fire protection system.

5. Add the suction pressure at the system flow demand (from step 2) to the net pressure from the pump (step 4). If this discharge pressure is greater than or equal to the system demand pressure from step 1, then go on in the procedure. If the pressure is less than the demand pressure, go back to step 3 and select a new pump.

6. Add the suction pressure at churn (from step 2) to the net pressure at churn (step 4). If this discharge pressure is less than or equal to the rated pressure for the components downstream of the fire pump, then this pump is acceptable. If the discharge pressure is greater than the rating of the fire protection system component(s), then go back to step 3 and select a different pump.