What is the relation between H and Q in a centrifugal pump?

What is the relation between H and Q in a centrifugal pump?

In centrifugal pumps the delivery head H depends on the flow rate Q. This relationship, also called pump performance, is illustrated by curves. During a bench test, the pump is operated at constant speed and the values Q and H are determined for the various operating points.

What is hydraulic efficiency of centrifugal pump?

Hydraulic efficiency (ηh) is also referred to as “vane efficiency” in the specialist centrifugal pump engineering literature and is the quotient of pump power output (PQ) and vane power (Pvane).

What is Q in centrifugal pump?

The flow rate (Q) of a centrifugal pump is the useful volume flow delivered by the pump via its outlet cross-section (see Pump discharge nozzle).

How do you calculate the hydraulic efficiency of a centrifugal pump?

Pump efficiency is the “water horsepower” divided by the “brake horsepower” and multiplied by 100 to present it as a percentage (see formulas in Image 1). Water horsepower is a system design tool and is the power that the pump would require to accomplish the hydraulic conditions if it was 100 percent efficient.

How do you determine the best efficiency point of a pump?

The best efficiency point (BEP) is about 85 percent of the shutoff head. The pump should be operated at, or close to, the best efficiency point. The key word here is “about.” This method has exceptions, depending on the pump design, application, and liquid.

What is the point at which the considered centrifugal pump operates at maximum efficiency?

Explanation: The point at which the centrifugal pump operates at maximum efficiency is called duty point. It is determined by the flow rate of the pump.

What is efficiency of hydraulic pump?

A typical hydraulic pump is only 80-90\% efficient. losses by utilizing a high viscosity index to maintain fluid viscosity in the optimum range across a wide operating temperature range. Increasing system pressure also reduces hydraulic pump efficiency.

What is volumetric efficiency of centrifugal pump?

Volumetric efficiency represents the power lost due to flow leakage through the wearing rings, the vane front clearances of semi-open impellers and the balancing holes in the rear shroud. Leakage usually increases with a decrease in specific speed, flow or a combination of the two.

What is Q in pump name plate?

Items specific to pumps may include: Rated Flow (Q) – gallons or liters per minute (GPM or lpm) Head pressure at rated flow – feet of water, pounds per square inch (psi), pascals. (pa) Power – Horsepower (HP)

What is Q and H in pump?

The pump selection of a pump is driven by the following main parameters: – Head (H) – Flow rate (Q) – Fluid characteristics (ρ, γ, T ….) Sometimes head can be confused with pressure during pump choice.

How do you calculate hydraulic efficiency?

A pump’s mechanical/hydraulic efficiency is determined by dividing the theoretical torque required to drive it by the actual torque required to drive it. A mechanical/hydraulic efficiency of 100\% would mean if the pump was delivering flow at zero pressure, no force or torque would be required to drive it.

Why does pump efficiency increase with flow rate?

The numerator in the efficiency equation is the product of head and flow rate primarily. Though flow rate continues to increase, the rate that output power increases is stunted by the loss in head. Peak efficiency occurs in a pump when the ratio of head and flow compared to the power into the system is maximized.

What is the efficiency of the centrifugal pump?

The efficiency of each machine is the ratio of the delivered power to the absorbed power. This ratio is indicated by the Greek letter η (eta). There are two ways to find out the return: Find out the efficiency of the centrifugal pump through the product selection software Wilo-Select; Calculate the efficiency of the centrifugal pump yourself.

How to create head power and efficiency characteristic curves for a pump?

To create head, power and efficiency characteristic curves for a centrifugal pump. Theory One way of illustrating pump characteristics is to construct contour lines of constant power or efficiency on a graph of pump head plotted against pump discharge.

How to find out the return of the centrifugal pump?

There are two ways to find out the return: 1 Find out the efficiency of the centrifugal pump through the product selection software Wilo-Select; 2 Calculate the efficiency of the centrifugal pump yourself. More

What is the maximum specific speed of a water pump?

Experience dictates that a pump’s efficiency reaches its maximum at specific speeds between 2,000 and 3,000, although favorable efficiency can occur at almost any specific speed. Also, the area around the BEP tends to be flatter and broader as specific speed decreases. Figure 2.