Friction loss in a fire hose is calculated by multiplying the friction loss coefficient by the flow rate divided by 100 to the power of two and multiplying that by the hose length divided by 100. Distance, diameter and GPM must be considered when calculating the friction loss.
The formula for calculating friction loss in a fire hose is C * (Q/100)^2 * L/100. C is the friction loss coefficient, Q is flow rate in gallons per minute and L is the length of the hose. The friction loss coefficient is determined by the diameter of the hose. The formula can be solved by hand, with a scientific calculator or by utilizing various friction loss calculators available on the Internet.
There are important points to remember when calculating friction loss in a fire hose. Friction loss varies with weave, quality, lining, type and age of the hose. It is nearly independent of pressure and increases as flow increases. The greater the length of the hose, the higher the friction loss is. Each doubling of water flow increases friction loss four times.
Friction develops between the inside surface of the hose and the water moving through it. The pounds per square inch are reduced at the other end of the hose because of this turbulence.