Pumps and Pump Selection Flashcards
(26 cards)
Mechanical devices that are used to move water. These devices provide energy to water and overcome friction during its conveyance.
Pumps
What are the common classification of pumps?
Rotary, reciprocating, and centrifugal pumps
What are the broader classification of pumps?
Positive displacement and Dynamic Pumps
A classification of pumps that discharges the same amount of water regardless of head.
Positive displacement pumps
A classification of pump which produce discharge which is inversely related to the pressure head; that is, they produce higher discharge at lower head and vice versa and require more energy.
Dynamic pumps or variable - displacement
A classification of pumps that comprises a set of vanes, referred to as impellers, that are enclosed within a stationary housing referred to as casing as shown in the figure.
Centrifugal Pumps
Performance of a pump by six parameters?
Capacity, Head, Power, Efficiency, Required Net Positive Suction Head, Specific Head
Denoted as Q is defined by the volume of water delivered per unit time is often expressed as liters per minute, cubic meter per second, etc.
Capacity
Defined as the net work done by the pump on a unit weight of water.
Head
When the pump is operating, pressure head, velocity head and friction head loss
become significant and when added to BLANCK, this constitutes the BLANCK
Total static head, Dynamic Head
Defined as the amount of power imparted to the pump shaft.
Brake Horsepower (BH)
The actual power delivered to the water by the pump.
Water Horsepower (WP)
Define by the percentage of power input to the pump shaft (brake power): that is, the ratio of WP to BP.
Pump Efficiency
It is the amount of energy needed to prevent the formation of vapor-filled cavities of water within the eye of the single- and first-stage impeller pumps to determine whether the liquid will vaporize at the lowest pressure point in the pump
Net Positive Suction Head
the minimum head at the pump entrance that prevents cavitation.
NPSHr
the atmospheric pressure minus all losses on the suction side of the pump, which include vapor pressure head, friction head, and static lift.
NPSHa
It is a dimensionless index combining pump capacity, head, and speed. It is
defined as the speed of a geometrically similar pump when discharging 1 gpm of
water against a total head of 1 ft.
Specific Speed (Ns)
The head related to zero Q (when the pump is operating against a close valve) is known as?
Shutoff Head
It is the relationship between several variables involved in pump performance.
Affinity Laws
directly proportional to the ratio of impeller speeds
Pump Capacity
directly proportional to the square of the ratio of impeller speeds
Head
directly proportional to the cube of the ratio of the impeller speed
Brake Horsepower (BH)
directly proportional to the ratio of the impeller diameters
Pump Capacity
directly proportional to the square of the ratio of impeller diameters
Head
