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BASIC FIRE FLOW FORMULA

Indication: Company Officers need to ensure sufficient water is available to contain and extinguish the fire. The Needed Fire Flow Formula is a helpful tool to determine total fire flow necessary. The Company Officer needs to determine the flow required and communicate the need to the Driver Operator. The Driver Operator can then ensure that an adequate and reliable water source is identified to supply the necessary fire flow. Limitations: Variables that effect fire flow include: fire load, concealed spaces, building construction, and configuration. Basic Formula:

Needed Fire Flow (NFF) = Length X Width X Percentage of fire involvement 3 Example: 1. To calculate the total fire flow for an entire building involved in fire:

2. To calculate the needed fire flow for a portion of the building involved in fire. In this example 25% of the entire structure is involved in fire:

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For additional floors, multiply the percent involved times the number of floors involved. Exposures Exposures are classified as internal (additional floors above the fire) or external (buildings adjacent to the involved structure).

1. For internal exposures (additional floors), a constant factor of 25% is added for each exposure (to a maximum of 5 floors) to Needed Fire Flow. Therefore the Exposure Formula is:

Length X Width + 25% for each floor above the fire (maximum of 5 floors) 3

This example shows the exposure of 2 additional floors above the fire (add 25% for each floor) to the NFF

2. For External Exposures (building adjacent to the involved structure), a constant factor of 25% is added for each side that has an exposure. Therefore the Exposure Formula is:

Length X Width + 25% for each side with an exposure

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This example shows exposures on the B and C side of the structure (add 25% for each side with an exposure) to the NFF