Single-Stage vs. Two-Stage Pumps

One important aspect of designing your new pumper is deciding what type and capacity pump you want to install. One of the concerns you should have is the water supply availability in your response area. Do you have a response district that has an abundant amount of fire hydrants? Or is your area mostly rural where you might have to rely on tanker operations. A 2,000 gpm pump for a rural operation might not be the best solution.

In any case, your choice should be made with your department's needs in mind. By this I mean don’t let anyone talk you into believing that one is better than the other. Both meet NFPA 1901 and 1911 standards and play an important fire service role.

The difference between the two is really simple. A single-stage pump has one dual suction impeller located on both sides of the vehicle, providing volume to all discharges on the vehicle. A two-stage pump has two suction impellers operating side by side. The operator must decide if he wants volume or more pressure by selecting a switch on the pump panel.

The decision to use single-stage pumps is common in 75 percent of the current apparatus purchases. If you feel that you need more than the 350 psi provided in a single-stage pump, then maybe the two-stage is right for you.

Training is also a factor in using a two-stage pump. The pump operator must be comfortable with a transfer valve and decide when to use volume versus pressure.

Remember, only design what is best for your department and don’t let others influence your purchase. Investigation and knowledge is your best friend.

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