Positive And Non Positive Displacment Pumps And Fans Flashcards
(113 cards)
Which of the following pumps is not dynamic:
Reciprocating
Centrifugal
Mixed flow
Axial flow
Reciprocating
When liquid is vaporized when pumping, what will happen?
Cavitation will occur
The capacity of the pump varies __________ when operated at a constant speed?
Directly with impeller diameter
When the pump inlet is above the level of the liquid in the supply reservoir, the pump has a suction ________?
Lift
What source of energy is available to allow liquid to enter a pump with suction lift?
Sucking action of the impeller to start the flow and atmospheric pressure to keep the flow moving
The impeller that helps push the liquid to the pump inlet?
Inducer
The NPSH available must be ______ or higher then the NPSH required to prevent cavitation?
10% or more
Pumps convert mechanical energy to______?
Hydraulic energy
Diffusers in pumps are mounted where?
Around the impeller
Gauge pressure is?
Atmospheric pressure minus absolute pressure
Absolute pressure is 14.7
Cavitation can be caused by ?
An increase in intake velocity or to large of a suction lift.
Bernoulli’s principle relates to dynamic pump systems in that they have?
Pressure head from the pressure acting upon the liquid
Velocity head from the speed of the liquid through the pipe
As pressure is increased, the boiling point of the liquid _______?
Increases
Pump performance curves are based on handling ________ water, and a specific gravity S.G of _____?
Cold
1
Friction losses through pipes depend on:
Inside diameter of the pipe
Fluid velocity
Surface finish
What things can happen if you install the pump with the wrong impeller rotation?
Inadequate discharge
Excessive power consumption
Pump won’t deliver fluid
An excessive suction lift can cause?
Insufficient atmospheric pressure at the intake
A suction piping condition to avoid is?
Reduced or restricted pipe diameter
Water hammer is a result of?
Opening and closing valves
Hydraulic slap is the result of ?
Check valve closing to quickly
Dynamic pump wear rings should be replaced when?
The clearance is increased 3 times the initial clearance
The screws of multiple screw pumps can use _______ to help stop the rotors from contacting each other.
The positon of timing gears
Pump motor power consumption may increase if the?
Pump packing gland is over tightened
Recirculation of fluid in the pump causes ?
Vortices and cavitation to be created