Pump theory

Pump types and theory

Types of pumps

• There are three main types that will be covered;– Rotary gear– Rotary vane– Centrifucal

• Centrifucal pumps are the most common type of pump found today, we will go into its use in depth

Rotary Gear Pumps

• Rotary pumps work by using tight tolerance gears to push water

• Tolerances are so tight that this pump will pump air

Rotary Vane Pumps

• These pumps work like the rotary gear pumps, but have vanes that can extend and retract

• This pump resists the effects of wear much better

Parts of the centrifical pump

Throttle controls the rotation speed of the impellor. More throttle = more pressure

How the centrifical pump works

How the centrifical pump works

How a centrifical pump works

Water supply for the pump

Booster tank

Intake from steamers and 2 ½

Tank to pump

Tank fill

Water being supplied to steamer intake into pump, flowing discharges and filling tank at the same time

Two stage pumps

two stage pump in volume

Two stage pump in pressure

Discharge Manifold

• The water being discharged from the pump is forced into a manifold; the junction for all discharge lines

• The manifold has all of the discharge valves that are controled from the pump panel

Using the relief valve

Relief Valves areUsed to sharp increases in pressure from going all the way through the attack lines and harming the nozzle crew

Excess pressure is dumped into the intake side of the pump

Using the relief valve

Using the relief valve

Centrifucal Pump Problems

• There are several conditions that can reduce the life or destroy the pump;– Running the pump with nothing flowing

or circulating

– Cavitating the pump– Running the pump dry

Pump Running, but not Discharging

• Water that is held in closed lines and in the pump will be warmed by the friction of the running pump

• If let go long enough, the water can boil and cavitate the pump

• Check to see if your hoselines are warm or hot

Pump Cavitation

• This occurs when there is too much air in the pump, or there is more water being discharged than is coming into the pump

• Sounds like gravel rolling around on the inside of the pump casing

Running the Pump Without Water

• Pumps need the water for cooling, lubrication, and to swell the packing

• Without water in the pump, the heat from friction will quickly destroy a pump

Conclusion