Pump Operating Prinicples Flashcards
Define capacity
The volume of liquid moving in a given amount of time
List 3 process characteristics that affect pump capacity
Upstream pressures
Downstream pressures
Viscosity
List 4 pump design characteristics that affect pump capacity
Impeller diameter
Impeller width
Pump head
Pump speed
Define pump head
a measure of pressure that the pump can produce, equal to the height of a column of liquid
Four advantages of centrifugal pumps
Higher reliability
Lower maintenance
Handles particulates better
Easier to control variable flow rate
How do centrifugal pumps increase liquid pressure?
By applying centrifugal force to the fluid
Define pump curve and system resistance curve
Shows the relationship between pump head and capacity
Define static head
Static head = pressure differential and elevation differential
Define dynamic head
Dynamic head = pipe friction and control valve
Describe the relationship between pump capacity and pump speed or impeller diameter
Capacity is proportional to speed or impeller diameter
Describe relationship between pump capacity and head
Head is proportional to the square of speed or impeller diameter
Describe four conditions that can cause an increase in dynamic head
Closing a valve
Exchanger fouling
Build up of solids in strainer backer
Increase in fluid viscosity
Define net positive suction head
NPSH - is the amount of head available in the liquid at pump suction minus the liquid vapour pressure expressed in liquid head
What can occur if available net positive suction head is less than required net positive suction head for a centrifugal pump?
Can cause cavitation
Define cavitation
The collapse of vapour bubbles inside the pump
