## How is gpm firefighting calculated?

## How is gpm firefighting calculated?

Example: For a 30′ x 50′ building that’s 25 percent involved, the flow would be 30 x 50 = 1,500 square feet, divided by 3 = 500 x 0.25 = 125 gpm. Based on that required fire flow, one handline pumped at the correct pressure should be able to produce the required gpm.

**How is NFF calculated?**

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.

### How do you calculate friction loss in firefighting?

When you need to calculate friction loss, find your desired gpm and multiply by 12. If you need 125 gpm on 100 feet of hose, that corresponds to number 2 on your finger. Multiply 2 by 12 to get 24; your friction loss is 24 psi.

**How is an airport’s ARFF index determined?**

An index is assigned to each FAA Part 139 certificate holder based on a combination of the air carrier aircraft length and the average number of daily departures. If the longest air carrier aircraft at the airport has five or more average daily departures, the matching index is used.

#### How is fire water demand calculated?

Per Capita Demand or Average Daily Demand Per capita demand or annual average daily demand is calculated as (Total yearly demand in litres/(365 * Design Population)).

**What is the fire flow formula?**

National Fire Academy Formula The NFA fire flow formula is: Required fire flow (gpm) = (length x width) ÷ 3. Using the same example, an IC arrives at a burning mercantile occupancy that measures 50 feet by 75 feet and is one story tall. The IC quickly determines that the area of the structure is 3,750 square feet.

## What is the minimum NFF required by the ISO?

500 gpm

The minimum NFF is 500 gpm at 20 psi for a duration of 1 hour. Appendix A provides the values for the construction factor C, for a range of construction classes (F) and effective areas (A). ISO uses the following definitions to determine the construction class for a building: a.

**How does friction loss affect GPM?**

Friction loss increases as flow (gpm) increases. Total friction loss varies with length — the greater the length, the higher the friction loss. Friction losses on reeled hose average about 21 percent more than for straight hose lays. Friction loss is nearly independent of pressure.

### What does the ARFF index mean?

United States ARFF Index A includes aircraft less than 90 feet in length. Index B includes aircraft at least 90 feet but less than 126 feet in length. Index C includes aircraft at least 126 feet but less than 159 feet in length. Index D includes aircraft at least 159 feet but less than 200 feet in length.

**What is ARFF response time?**

The maximum response time from initial notification until the first vehicle is on scene and spraying fire retardant is defined by State regulation and generally ranges from three to four minutes under conditions of good visibility and uncontaminated surfaces.

#### How do you calculate gpm from PSI?

To calculate GPM from pressure in PSI for water, follow these steps:

- Measure the pressure inside the tank using a pressure gauge.
- Subtract the atmospheric pressure from the tank pressure.
- Multiply the result from step 2 by 2 and divide by the density of water.