What does GPM stand for and why is it important?

• A. Grams Per Meter; used for chemical concentration.
• B. Gases Per Meter; used for ventilation.
• C. Gallons Per Minute; it measures water flow for extinguishment and hose sizing.
• D. Gallons Per Minute; measures pressure in the system.

Answer: (C)

GPM stands for gallons per minute, the rate at which water flows from the pump through the hose to the nozzle, measured each minute. This flow rate is essential because it tells you how much water you can apply to the fire, which directly affects cooling, steam production, and overall extinguishment progress. When you’re sizing hoses and selecting nozzles, you use GPM to ensure you can deliver the needed water without overburdening the pump or incurring excessive friction losses along the hose. In practice, higher GPM requires enough pump discharge pressure and often larger hose to keep friction losses manageable, while too little GPM may not control the fire effectively. GPM is about volume of water per time, not about concentration in a solution, gas movement, or system pressure (which is measured as psi).