Pumps Quiz Flashcards
A fixed displacement pump must have what to limit system pressure?
Relief valve
Purpose of a relief valve?
Limits system pressure
How are packing rings supposed to be cut?
At an angle leaving no gaps in the ring.
One of the oldest and most widely used seal is what?
Stuffing box/Gland Packing
Where does the lantern ring need To be positioned?
Directly under the Inlet port
The most common type of non positive displacement pump…
Centrifugal
What is injected into the stuffing box?
Flush water
3 things that flush water does?
- Cools shaft
- Keeps the packing moist
- Flushes contaminants
2 types of seals?
Compression packing and mechanical seal
3 types of impeller styles?
Enclosed, semi open and open
What are the components of a stuffing box seal system?
Stuffing Box
Gland follower
Rings of packing
Lantern ring
What is the meaning of head?
Height of a liquid
3 things that determine the capacity of a pump?
- Size of impeller
- Speed of impeller
- Viscosity of liquid
A positive pressure at the pump Inlet?
Positive head
The distance which the pump lifts the liquid
Total head
Distance that the liquid must be lifted to the pump?
Negative head
What is the definition of pumps?
Lifts liquids against gravity or exhausts gasses.
What unit are industrial pumps rated in?
GPM (Gallons Per Minute)
What 3 things determine pumps capacity?
RPM of pump
Viscosity of liquid
Impeller size
What is a pumps capacity?
Amount of fluid a pump can move in a given time
What is discharge head?
The pressure at discharge
What is the limit for discharge pressure on typical centrifugal pumps?
250psi
What type of centrifugal pump can get past 250psi?
Multistage
What do vanes do?
Guide liquid to outside of the housing
What are the 2 common case designs?
Split Case and Endsuction
What is the disadvantage of endsuction pumps?
Create thrust load, which causes the need for better bearings
How do split casing pumps avoid thrust load?
Liquid is on both sides of impeller
What are the rings on either side of the impeller in a split casing pump?
Wear Rings
What is the purpose of wear rings?
Wear out before other pump components
What is pressure?
Force Per Unit Area or lbs/sq in
What is Suction Head?
Positive Head (Pressure created from fluid coming from above pump inlet)
What is Suction Lift?
Negative Head (Pressure created from fluid coming from below pump inlet, needs primed)
How do positive displacement pumps operate?
Volume changes from maximum to minimum during cycles.
How do Non Positive Displacement Pumps operate?
Volume stays the same during cycles.
Is the total head higher or lower typically on a pump with positive head?
Higher
Is the total head higher or lower typically on a pump with nagative head?
Lower
