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2-1 Types Of Fire PumpsTypes of Fire Pumps Types of Fire Pumps Positive displacement Centrifugal Positive Displacement Pump Centrifugal Pumps Positive Displacement Pumps Can pump air Has a small amount of slippage Ability of water to pass through the inner workings of the pump, not allowing 100% discharge Has a fixed displacement of water Piston Pump Rotary Gear Rotary Vane Types of Piston Pumps Single action Pumps in a forward stroke only Double action Pumps in both forward and reverse strokes Examples Backpack pump Foam injection pump Wells Bicycle pump Piston Pumps Discharge Intake Floating Valves Piston Cylinder Types of Rotary Pumps Commonly used as a primer pump 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 Intake Discharge Types of Rotary Pumps Rotary vane Movable vanes that automatically compensate for wear and maintain a tighter fit Vanes are forced against the outer housing by centrifugal force Vanes Discharge Rotor Drive shaft Intake Centrifugal Pumps Can not pump air Capable of 100% slippage The main fire pump used on modern fire apparatus Classified as a nonpositive displacement pump Imparts velocity on water and converts it to pressure Single or multiple stage Casing Intake Impeller Volute CavityEye Discharge Hub Shroud Vanes Shaft Impeller Hub Vanes Shroud Centrifugal Pumps Pump Wear Rings Between the pump casing and the hub Seal is between the lower pressure of the intake side and the higher pressure in the volute Dirt/sediment can damage ring resulting in decreased pump effectiveness Pump Packing Located around the pump shaft, within the stuffing box Lubricates and seals pump shaft Too loose Can result in drafting difficulties and pump efficiency Too tight Can result in damaging the pump shaft due to overheating Principles Of Operation Centrifugal force Based on the principle that a rapidly revolving impeller hurls the water from the impeller eye outward The faster the impeller is turned, the farther the water is thrown Increasing the velocity Principles Of Operation Influencing Factors Amount of water being discharged Speed at which the impeller is turning Doubling the speed results in four times the pressure Pressure of water when it enters the pump from a pressurized source Pressure (Series) Setting Intake Clapper Valve Transfer Valve 2nd Stage1st Stage 500 GPM @150psi + 150psi 500 GPM @ 300 psi Pressure (Series) Setting Parallel (Volume) Setting Intake Transfer Valve Clapper Valve 1st Stage 2nd Stage 500 GPM @150psi 500 GPM @150psi 1000 GPM @ 150 psi Volume (Parallel) Setting