How much psi should be added for each appliance when calculating pressure loss?

In calculating pressure loss for fire operations, adding a set amount of pressure for each appliance ensures sufficient flow and pressure at the nozzle. The correct addition of 10 psi for each appliance reflects the standard practice used among fire departments. This value is based on common guidelines in the fire service to account for the resistance created by additional equipment such as hoses, valves, and other appliances in the water supply line.

Using 10 psi per appliance provides a reasonable estimate of the pressure needed to overcome the friction loss and ensure effective operation, particularly when multiple tools, such as hoses and nozzles, are in use simultaneously. It is critical for ensuring that the water provided meets the demands of the incident response without falling short due to inadequate pressure. Other values, like 5 psi or higher ones such as 15 or 20 psi, may not accurately represent a balance between flow requirements and operational efficiency under typical conditions encountered by fire responders.