Unit 2-1 Types of Fire Pumps

Types of Fire Pumps

Driver/Operator 1B September 2003

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Types of Fire Pumps ƒ Positive displacement ƒ Centrifugal

Driver/Operator 1B September 2003

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Positive Displacement Pump

Driver/Operator 1B September 2003

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Centrifugal Pumps

Driver/Operator 1B September 2003

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Positive Displacement Pumps ƒ Can pump air ƒ Has a small amount of slippage  Ability of water to pass through the inner workings of the pump, not allowing 100% discharge

ƒ Has a fixed displacement of water

Driver/Operator 1B September 2003

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Piston Pump

Rotary Gear

Rotary Vane

Driver/Operator 1B September 2003

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Types of Piston Pumps ƒ Single action  Pumps in a forward stroke only

ƒ Double action  Pumps in both forward and reverse strokes

ƒ Examples  Backpack pump  Foam injection pump  Wells  Bicycle pump Driver/Operator 1B September 2003

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Piston Pumps Cylinder Discharge Piston Floating Valves

Intake

Types of Rotary Pumps ƒ Commonly used in the fire service as a primer pump ƒ Rotary gear  Two gears that rotate in a tightly meshed pattern forming pockets  As each gear tooth reaches the discharge chamber, the air or water contained in that pocket is forced out of the pump Driver/Operator 1B September 2003

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Intake

Discharge

Types of Rotary Pumps ƒ Rotary vane  Movable vanes that automatically compensate for wear and maintain a tighter fit  Vanes are forced against the outer housing by centrifugal force

Driver/Operator 1B September 2003

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Intake Rotor

Drive shaft Vanes

Discharge

Centrifugal Pumps ƒ ƒ ƒ

Can not pump air Capable of 100% slippage The main fire pump used on modern fire apparatus ƒ Classified as a nonpositive displacement pump ƒ Imparts velocity on water and converts it to pressure ƒ Single or multiple stage Driver/Operator 1B September 2003

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Casing Discharge

Hub Intake

Shaft

Shroud Impeller Vanes Eye

Volute Cavity Driver/Operator 1B September 2003

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Vane s

Shrou d

Hub

Impeller

Centrifugal Pumps

Pump Wear Rings ƒ Between the pump casing and the hub ƒ Seal is between the lower pressure of the intake side and the higher pressure in the volute ƒ Dirt/sediment can damage ring resulting in decreased pump effectiveness Driver/Operator 1B September 2003

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Pump Packing ƒ Located around the pump shaft, within the stuffing box ƒ Lubricates and seals pump shaft ƒ Too loose  Can result in drafting difficulties and pump efficiency

ƒ Too tight  Can result in damaging the pump shaft due to overheating Driver/Operator 1B September 2003

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Principles Of Operation ƒ Centrifugal force ƒ Based on the principle that a rapidly revolving impeller hurls the water from the impeller eye outward ƒ The faster the impeller is turned, the farther the water is thrown  Increasing the velocity Driver/Operator 1B September 2003

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Principles Of Operation

Driver/Operator 1B September 2003

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Influencing Factors ƒ Amount of water being discharged ƒ Speed at which the impeller is turning  Doubling the speed results in four times the pressure

ƒ Pressure of water when it enters the pump from a pressurized source Driver/Operator 1B September 2003

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Pressure (Series) Setting

Pressure (Series) Setting 500 GPM @ 300 psi 500 GPM @150psi

+ 150psi

1st Stage

2nd Stage Transfer Valve

Clapper Valve

Intake Driver/Operator 1B September 2003

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Parallel (Volume) Setting

Volume (Parallel) Setting 1000 GPM @ 150 psi 500 GPM @150psi

500 GPM @150psi

1st Stage

2nd Stage Transfer Valve Clapper Valve

Intake Driver/Operator 1B September 2003

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