There are three major types of pump used on fire service apparatus, mid mount, power take off (PTO) and auxiliary, all are capable of pumping at 150-400 psi. 

Mid mount pumps are mounted inside the body of the vehicle and are powered through a transfer case, power is diverted from the wheels to the pump when the pump is operating. This type of pump offers the most pumping capacity but can not move while the pump is engaged, the mid mount is most common in structural pumpers since that type of fire requires the most water and little mobility. This type of pump typically is capable of pumping 750-1500 gallons of water per minute and their are examples capable of pumping  up to 8000 gallons per minute on specialized vehicles. Most modern fire engines have mid mount pumps of around 1000 gallons per minute with 2250 gallons per minute being the maximum practical.  

PTO or power take off pumps are similar to mid mount pumps but they take their power from the transmission, this allows them to move and pump although the pump pressure and vehicle speed are tied together making it a tricky balancing act matching water flow to the firefighters walking speed, to pump while sitting still the transmission is placed in neutral. These pumps are generally capable of flowing 100-1000 gallons per minute with 250-500 gallons per minute being a common size.

Auxiliary pumps are powered by a gasoline or diesel motor independent of the vehicles motor. This makes the auxiliary pump the best for mobile pumping operations since it is completely separate from the vehicles operation, the vehicle can drive at any speed or stop without changing the flow of water. These pumps can be found capable of pumping 5-500 gallons per minute but most fall between 60 and 250. Some vehicles mount the motor and pump inside the vehicles body, others mount them externally. This type of pump is common on so called slip on units which are self contained fire pumper units that can be easily mounted on a standard flatbed or pick up truck.  

Front mount pumps are occasionally seen, these used to be very popular because they are easy to put on a truck and are relatively inexpensive since they mount in front of the grill. They may be powered through a transfer case like a mid mount or through a PTO. The disadvantage to these pumps is they are exposed making them more prone to damage and the block air flow to the radiator. Front mount pumps generally vary in size between 100 and 1250 gallons per minute depending on the intended use.

A general rule of thumb to determine a pumpers capacity is to add up all the 2.5" discharges and assume 250 gallons per minute for each, this will provide an estimate of the minimum pump size although it is not unusual for a department to request additional discharges.  

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Front mount pump Front mount pump Front mount pump Front mount pump
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Auxiliary engine driven pump Auxiliary engine driven pump Auxiliary engine driven pump Slip on pump unit
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Slip on pump unit Slip on pump unit Controls to slip on pump unit Auxiliary engine driven pump
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Slip on pump unit Slip on pump unit Auxiliary engine driven pump 5" front intake with valve & hose
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5" side intake with wye & discharge with 5" adaptor 2.5" intake 5" side intake & 2.5" discharges 5" side intake & 2.5" discharges
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5" side intake with valve & 2.5" discharges 2.5" intake 2.5" discharge 5" side intake with valve & 2.5" discharges
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Side intake with valve      


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