Positive Displacement Pumps Vs Dynamic Pumps Flashcards
What type of pump has a constant flow rate regardless of pressure changes?
Positive Displacement Pumps
Positive displacement pumps maintain a steady flow rate even when the pressure fluctuates.
How does viscosity affect the flow rate in positive displacement pumps?
As viscosity increases, flow rate increases because internal clearances are filled
This means that thicker fluids lead to higher flow rates in positive displacement pumps.
What is a general characteristic of positive displacement pumps regarding pressure?
Can produce very high pressures
Positive displacement pumps are capable of achieving high pressure levels.
What type of delivery may positive displacement pumps exhibit?
Pulsating delivery
This refers to the non-continuous flow that can occur with positive displacement pumps.
What capability do positive displacement pumps have regarding suction lift?
Capable of creating a suction lift without being primed due to inlet/discharge seal
This allows them to draw fluid without needing to be filled with liquid first.
How can the flow rate be varied in positive displacement pumps?
Increasing or decreasing rpm or stroke
Adjusting the speed of the pump or the number of strokes per minute changes the flow rate.
What is required on the discharge side of positive displacement pumps?
Require a relief valve
This prevents excessive pressure build-up in the system.
What is a defining characteristic of dynamic pumps regarding flow rate?
Varying flow rate depending on pressure or head
Dynamic pumps adjust their flow based on the system’s pressure conditions.
How does viscosity affect the flow rate in dynamic pumps?
As viscosity increases, flow rate drops
Thicker fluids result in lower flow rates for dynamic pumps.
What is a general pressure characteristic of dynamic pumps?
Produce low pressures
Dynamic pumps typically generate less pressure compared to positive displacement pumps.
What type of delivery do dynamic pumps provide?
Smooth continuous delivery
This means that dynamic pumps maintain a steady and uninterrupted flow.
What is necessary for dynamic pumps to create a suction lift?
Need to be primed
Dynamic pumps require fluid in the pump before they can create suction.
What is the minimum operational requirement for dynamic pumps to create flow?
Need to operate above a minimum speed
If the pump does not reach this speed, it will not produce flow.
Do dynamic pumps require a relief valve?
Do not require a relief valve
This is because they manage pressure differently compared to positive displacement pumps.
