Where is the relay pumper positioned in relation to the source pumper and the attack pumper?

• A. Between the source pumper and the attack pumper
• B. Ahead of the source pumper
• C. Behind the attack pumper
• D. On the fire hydrant

Answer: (A)

In relay pumping, the goal is to keep enough pressure along a long hose lay by adding a booster pumper in the middle of the run. Water is drawn from the hydrant by the source pumper, then it goes to the relay pumper, which increases the pressure (and can help maintain volume), and finally it reaches the attack pumper near the fire, which delivers the water through the attack line. That setup means the relay pumper must be positioned between the source pumper and the attack pumper so the water is boosted as it travels toward the scene. If the relay pumper were placed ahead of the source pumper, there wouldn’t be pressurized water to boost from the hydrant. If it were behind the attack pumper, the attack would not receive the boosted pressure needed. If it were simply on the hydrant, it wouldn’t sit in the necessary position to boost the pressure along the long run.