Axial Pump
A dynamic pump that accelerates fluid in a straight line
Cavitation
A formation and collapse of gas pickets around impellers during pump operation
What causes cavitation
A result of insufficient suction head at the inlet of the pump
Diaphragm pump
A reciprocating pump that uses a flexible diaphragm to positively displace fluids
Impeller
A device attached to the shaft of a centrifugal pump that imparts velocity and pressure to a liquid
Lobe pump
A rotary pump that uses kidney-bean shaped lobes to displace and transfer fluid
What does NPSH stand for?
Net Positive Suction Head
What does NPSHa stand for
Net Positive Suction Head Available
What does NPSHr
Net Positive Suction Head required
What is NPSH
The head in feet of liquid necessary to push the required amount of liquid into the impeller of of dynamic pump without causing cavitation
What is positive displacement
Class of equipment, such as pumps and compressors that move specific amounts of liquids
What is a pulsation dampener
A device used in the suction or discharge line to reduce pressure variations
Reciprocating pump
A positive displacement pump that uses a plunger, piston or diaphragm
Rotary Pump
A positive displacement pump that uses rotating elements to move liquids
Screw pump
A rotary pump that displaces liquid with a screw
Slip
The percentage of fluid that leaks or slips past the internal clearances of a pump over a given time
Vane pump
a rotary pump that uses flexible or rigid vanes to displace fluids
What are the two general classifications of pumps
Dynamic or positive displacement
Which two ways can dynamic pumps move liquids
Axially or centrifugally
What two ways do Positive Displacement Pumps move liquids
Rotary or reciprocating motion
What characterizes the amount of fluid a PD Pump displaces on each stroke
Each stroke displaces a SPECIFIC amount of fluid that is the same on every stroke
The first Reciprocating Pump was created by whom?
A Greek name Ctesibius
The first true centrifugal pump was invented by whom
French inventor Denis Papin
A centrifugal pump can have what percentage of slip if the discharge valve is closed
100%
What is a volute
A specially designed chamber that widens within the pump that liquid accelerates out of
When the discharge valve is closed on a PD pump what can happen
Pressure increases on every stroke, pump can be damaged if a relief valve is not provided
What are the two classifications of Dynamic pumps
Centrifugal or axial
Centrifugal Pumps operates on what principle
Centrifugal force
How does an axial Pump move liquids
In a straight line
As liquid leaves the volute what two things happen
In slows down and creates pressure
Liquid enters a centrifugal pump at the
Inlet or suction eye
What are some of the disadvantages of a centrifugal pump
They are not self priming and respond poorly to viscous materials
What is suction head
The term used to describe the pressure required to force liquid into into a pump
What is differentiates a single and multistage pump
The number of impellers used
What are the two major classifications of Positive Displacement Pumps.
Rotary and Reciprocating
What type of pump is used to move viscous fluids like heavy hydrocarbons, syrup, paint or slurries.
Rotary type PD Pump
What are the four main types of rotary PD pumps
Screw, internal and extension gear, vane and lobe
External Gear Pumps are made up of what
Two intersecting gears that rotate parallel to each other. One is the idler gear the other is the driver
What is another name for an internal gear pump
Gear within a gear pump
What does a sliding vane pump consist of
Vanes attached to a rotor or impeller that rotate inside an oversized circular casing
Where are vane pumps mostly used
In hydraulic systems, vacuum systems and low pressure oil systems
What does a flexible vane pump composed of
A rotor composed soft elastomer impeller keyed to over the driveshaft
What type of service are flexible vane pumps mostly used in
Vacuum service
What does a lobe pump consist of
Two rotating lobe shaped screws that mesh during operation.
How do lobe pumps operate
As the lobes turn, voices are created that compress liquids around the outside of the pumping chamber
What are lobe pumps designed to do
Provide high flow rates at low pressures
What are some of the characteristics of reciprocating pumps
Can transfer small volumes of liquids a high pressures, they are self priming and operated at low speeds
What are the characteristics of a piston pump
Uses a piston and back and forth motion to displace liquids. Has a suction stroke and discharge stroke
What are the characteristics of a plunger pump
Operates with a back and forth motion, uses a plunger to displace controlled amounts of fluid
What problems do pulsation dampeners offset.
It offsets the problem of pulsing or sorting flow rates
What is another term for a primed pump
Liquid full/air free
When pumps are in a series what is increased and what remains the same
The discharge pressure increases and volume stays the same
When pumps are parallel what is increased and what stays the same
Volume increases but discharge pressure remains the same
What are four factors that affect a pumps suction pressure
Temperature, viscosity, pressure, line restriction
What are the two types of drivers commonly used in the industry
Electric motor and steam turbine