Chapter 6 Flashcards
The work of pumping consists of discharging a quantity of liquid or gas against…
Resistance
The amount of force required to move a substance depends largely on its
Density, the height it must be raised, friction in pipe and pressure pumped against
The forces which a pump must overcome to pump are often referred to as
Total pump head
The force exerted by pumps on the materials pumped may be due to…
Displacement, centrifugal action or due to jet action or propulsion
Check valves placed in the suction line to prevent what
The liquid flowing out of the pump and suction line when the pump is stopped ( losing its prime )
When a fluid flows through a Venturi or restriction it will gain
Velocity or kinetic energy but loses pressure energy
One advantage of a centrifugal pump is its ability to
Handle dirty water
What do wear rings do
Help with leakage and wear protection of case and impeller
To reduce recirculation loss or leakage and permit maintenance of pumps at high efficiency what is used
Clearance or labyrinth rings (wear) are installed on impellers, shafts, and pump casings
In multi stage pumps recirculation losses can occur where
From higher to lower stage along the pump shaft
Seal water is…
Enters through the lantern ring to lubricate and seal the space between the packing and shaft
A pump case does what
Provide the means for converting the kinetic energy in the liquid to potential or pressure energy
The gradual increase in sectional area inside the pump case does what
Reduces the velocity and the friction loss
One foot of pump head is the static force exerted by a Column of water one foot high on an area of one square inch it is equal to…
.434 pounds of pressure
Head generated is always expressed in…
Feet of liquid
As flow increases what else increases
Friction
As horsepower input to the pump increases discharge pressure will fall but the discharge rate will do what
Rate of pump increases
As flow increases what happens to the efficiency
It drops due to the increasing friction and other losses
The relation between the capacity, rotative speed, and head developed by an impeller is called what
Specific speed
To prevent liquid from flashing into vapor there must be sufficient…
Pressure on the liquid
Priming a liquid pump usually refers to the complete removal of all…
Air/vapor
Excessive air leaks in the inlet or suction side of a liquid pump will cause the pump to become…
Vapor locked
