Pumps Flashcards
The two basic classifications of pumps
Dynamic and Positive displacement
This uses centrifugal force to spin it outwards and move fluid
Dynamic pumps (non-positive displacement)
The four categories of centrifugal pumps based on flow
Radial
Mixed
Axial
Peripheral
The pressure that a pump has to overcome to be able to move liquid through the system
Pump head
Pressure converted to a height of a column in which the pumped liquid can maintain
Head (measured in feet or meters)
The vertical distance from the liquid supply level to a pump centre line when the liquid supply level is below the pump centre line
Static suction lift
The vertical distance from the liquid supply level to a pump centre line when the supply level is above the pump centre line
Static suction head
The vertical distance from the pump centre line to either the surface of the liquid in the discharge tank or to the point of discharge
Static discharge head
The vertical distance from the liquid supply level to the surface of the liquid in the discharge tank or to the point of discharge
Total static head
The pressure needed by the fluid to overcome friction as it moves through piping, valves and fittings in the system
Frictional loss
The force causing the fluid to flow through a chamber which is due to the velocity of the fluid
Velocity head
The term most used in industry to describe a pumps head
Total dynamic head
To prevent cavitation an vapour binding and ensure maximum flow through the pump, the required pressure at the pump suction is called this
Net positive suction head (NPSH)
How are pumps sized
Diameter of discharge nozzle, suction nozzle, and impeller
In this pump, the rotating impeller discharges the fluid into a spiral-shaped cavity
Volute pumps (radial) Has tangential velocity
These pumps create multiple volutes
Diffuser pumps (radial)
In these pumps the impeller moves liquid through the casing without changing it’s direction
Axial-flow (impeller like a ships propeller)
Mounted vertically, below liquid being pumped
This pump combines characteristics of radial and axial flow pumps
Mixed-flow
Pumps equipped with several impellers connected in series
Multi-stage pumps
Type of peripheral pump that creates high pressure for their size, used in compact areas
Regenerative turbine pump
Two types of pump casings
Split
Barrel (for multi-stage high pressure centrifugal pumps)
How much wear is not allowable for efficiency
If it exceeds three times the initial clearance in the pump (can be fixed by changing wear rings)
3 types of wear rings
Flat, Stepped (L-shaped), Labyrinth
Often made of bronze or cast iron
When are mechanical seals used
When leakage is not wanted due to whats being pumped
Used in high pressures
