If your department uses or plans to use the rural hitch method for tanker operations, it is important to determine the pump-off limit of your tanker. Simply having a tanker with a pump rated at a certain capacity does not guarantee that it can pump off water at that capacity.
Factors such as the size of the tank-to-pump line and discharge piping or valve limitations often result in pump-off rates that are lower than the pump’s rated capacity. The tanker featured in this news story is equipped with a 500 gallon-per-minute, PTO-driven fire pump, but it lacks a high-flow discharge. A single discharge line was not able to supply 500 gallons per minute to the flow diffuser. When we tried using two discharge lines, there was no improvement in the pump-off rate, confirming that the tank-to-pump line size was the limiting factor.
This issue is difficult to remedy with an existing tanker, but it helps to understand the practical limitations of the rural hitch when pumping off water from this tanker. Testing your tanker and knowing its pump-off limit is essential.
