Chapter 18: Firefighting, Rescue and Assistance
Drop Pump and AFFF F.36. General
Use of a drop pump allows AFFF concentrate to be proportioned with water, adequately agitated, and delivered at a relatively high rate. A drop pump is designed to pump a large volume of water at low pressure.
F.37. Description
A P1 or P5 drop pump is designed to pump a large volume of water at low pressure. The drop pump is not intended for firefighting and therefore is not equipped with fire hose connections.
F.38. Safety precautions
AFFF must be mixed with water. Do not apply it to a fire directly from its container or when it has been mixed with water manually, i.e., without using a mechanical foam nozzle or a drop pump. There are drawbacks to using a drop pump in place of a mechanical foam nozzle. Once a canister is empty, foam application must be halted so it can be refilled. In addition, the quality and density of foam is not optimum.
F.39. Operating procedures
It is not possible to apply mechanical foam with a drop pump in the conventional way by using an in-line proportioner and/or a mechanical foam nozzle. However, a drop pump can still be used for foam delivery by following the procedure below: Step Procedure 1 Break a pump out from its storage container and set it up to take suction. 2 Fill the storage container with water using the pump discharge hose. It will hold about 38 gallons of water. 3 Pour about 2 gallons of AFFF (about one-third of a standard AFFF container) into the pump's storage container. 4 After the storage container is full of water/AFFF mixture, transfer the pump's suction hose from over the side to the storage container (suction is taken from there). A discharge hose is about 15 feet in length. Use it as if it were a mechanical foam nozzle to fight fire in a conventional manner. This method allows a high volume of foam (AFFF) to be delivered in a short period of time.
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