What is the difference between drafting and relay pumping?

What is the difference between drafting and relay pumping?

• A. Drafting uses electric power; relay uses diesel
• B. Drafting is drawing water from a static source into the pump; relay pumping is chaining multiple pumps to relay water from a source to the attack engine
• C. Drafting is indoor; relay is outdoor
• D. Drafting increases nozzle pressure; relay decreases

Answer: (B)

The main idea is how water is delivered to the fire pump. Drafting means the pump draws water directly from a static source through its suction, pulling the water up into the pump to supply flow. This is used when a nearby water source like a pond, tank, or hydrant is accessible and can be reached by suction, with the pump lifting the water up and into the system. Relay pumping, on the other hand, uses a series of pumps arranged to move water from the source to the attack engine. Water is passed from one pump to the next (often with each pump discharging into the next pump’s intake or through a staged discharge system) to overcome distance, elevation, or suction limitations, so the final engine receives adequate flow and pressure. The other options miss the defining difference: the method is not fixed by power source (electric vs diesel), nor by indoor vs outdoor placement, nor by a guaranteed increase or decrease in nozzle pressure.

The main idea is how water is delivered to the fire pump. Drafting means the pump draws water directly from a static source through its suction, pulling the water up into the pump to supply flow. This is used when a nearby water source like a pond, tank, or hydrant is accessible and can be reached by suction, with the pump lifting the water up and into the system.

Relay pumping, on the other hand, uses a series of pumps arranged to move water from the source to the attack engine. Water is passed from one pump to the next (often with each pump discharging into the next pump’s intake or through a staged discharge system) to overcome distance, elevation, or suction limitations, so the final engine receives adequate flow and pressure.

The other options miss the defining difference: the method is not fixed by power source (electric vs diesel), nor by indoor vs outdoor placement, nor by a guaranteed increase or decrease in nozzle pressure.