Contents
What is pump head coefficient?
The head coefficient (ψ) is a characteristic coefficient derived from the corresponding physical quantity according to the affinity laws and used to characterise the operating behaviour. It characterises the head (H) of the pump: When the head varies at constant rotational pump speed, ψ ~ H.
What is flow coefficient in centrifugal pump?
The flow coefficient (φ) is a dimensionless quantity used to describe the volume flow rate. It is also referred to as the volume or volume flow coefficient and characterises the flow rate (Q). When the flow rate varies at constant rotational pump speed, vm ~ Q and therefore φ ~ Q.
How do I choose a pump size?
In pump sizing, two factors are needed to select a pump: flow and pressure. Flow is generally measured in gallons per minute (gpm). The max instantaneous flow that will be entering the pump’s basin needs to be determined so that a pump can be selected to efficiently maintain the system.
How is head coefficient calculated?
The head H is proportional to the square of fluid velocities u2 with g the gravitational constant for dimensional consistency. Velocity u is proportional to the rotational speed N multiplied with the rotor diameter. This relation is therefore rewritten, such that the head coefficient is obtained.
How do you calculate the coefficient of discharge?
The discharge coefficient of an orifice or nozzle is defined as the ratio of the actual to theoretical flow rate:
- Cd=Measured Flow RateTheoretical Flow Rate (1)
- η=σΔp12ρ¯V2 (6)
- ξ=σΔp¯Δp (7)
What is the pump head calculation?
It is represented by the letter H and is usually expressed by the height m of the liquid column. The pump head H=z+hw z is the height difference of the pumping height, that is, the water level from the inlet to the water surface at the exit.
What is the head of centrifugal pump?
In Newtonian (true) fluids (non-viscous liquids, such as water or gasoline), the term head is the measurement of the kinetic energy that a centrifugal pump creates. Imagine a pipe shooting a jet of water straight into the air. The height that the water reaches is the head.
Which pump has high volumetric capacity?
Positive-displacement pumps are capable of developing high pressures while operating at low suction pressures. They are commonly referred to as constant-volume pumps. Unlike centrifugal pumps, their capacity is not affected by the pressure against which they operate.
How do I choose a pump type?
Before you can select a pump that will fit your needs, you must know four things: 1) the total head or pressure against which it must operate, 2) the desired flow rate, 3) the suction lift, and 4) characteristics of the fluid.
Why are dimensionless parameters used in the analysis of pumps?
The dimensionless equations were useful to determine which discharge should be adopted so that the system would be more efficient hydro and energetically and, also, to determine how much more energy would be consumed in the case of alteration of the point of operation of the pump by a throttling valve.
What is the range of coefficient of discharge?
0.61 to 0.79.