What are the different factors affecting pump efficiency?
Important factors affecting pump performance are surface roughness; internal clearances; mechanical losses, such as those related to bearings, lip seals, mechanical seals, and packing; high suction specific speed; impeller trim; and the viscosity of the fluid pumped.
What are the losses in pump?
Fluid flow through the impeller, the pump housing, there is a change of flow rate and inverse pressure gradient magnitude and direction of the circulation and cause vortex, resulting in energy loss, this loss is called hydraulic losses.
What are the different losses takes place in a pump impeller?
Losses in a Centrifugal Pump Mechanical friction power loss due to friction between the fixed and rotating parts in the bearing and stuffing boxes. Disc friction power loss due to friction between the rotating faces of the impeller (or disc) and the liquid. Leakage and recirculation power loss.
What are the causes of low pump efficiency?
Lower efficiencies are due to energy losses caused by friction, leakages originating from pressure differentials within the pump case and losses due to a more complex nature. The efficiency of a particular pump is estimated by determining two values. These values are pump flow rate and total head.
What is the formula for calculating pump efficiency?
This is the efficiency of the pump in turning input shaft power (from the motor) into useful power output to the fluid (Hydraulic Power), it is calculated using the following formula: Pump Hydraulic Efficiency (%) = Pump Hydraulic Power Output (kW) x 100 / Pump Input Shaft Power (kW).
What is manometric efficiency?
i. The ratio of the actual head developed to the velocity pressure of air moving at the fan-tip speed, equal to one-half the theoretical head of a radial-tip fan.
What is the impact on flow and pressure when the impeller of a pump is trimmed?
When you trim an impeller, you’ll notice a reduction in the head pressure, flow rate and power draw on the motor. In most instances, the performance curve of a centrifugal pump will detail the performance of a few impeller diameters – minimum to maximum allowable diameter.
What is pump efficiency formula?
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). Brake horsepower (BHP) is the shaft horsepower the pump requires to meet the load. Brake horsepower takes pump efficiency into account, but not the motor efficiency.
How is overall efficiency calculated?
The work efficiency formula is efficiency = output / input, and you can multiply the result by 100 to get work efficiency as a percentage.
What are the different types of losses in pump?
Friction loss in bearing and glands. The surface of impeller and casing some impellers are highly polished to minimize friction losses. Head in pumps due to shock at entry and exit to impeller vanes and eddies formed by vane edges. Leakage loss in thrust balance devices, gland sealing clearance between cut water and casing and bearing seals.
What is the friction loss of a centrifugal pump?
At specific speeds below 2,000, friction losses range from 1 to 2.5 percent, but losses can approach 10 percent at a specific speed of 5,000 and higher. Typically, volute design begins with the throat (see Figure 1).
What causes losses in a frame mounted pump?
The final piece of the pump efficiency puzzle is that of mechanical losses, although some of these losses are not always included in published efficiency curves. In the case of a frame-mounted pump, these losses are caused by the shaft bearings and the mechanical seal or packing.
Why is a water pump not 100 percent efficient?
No pump is 100 percent efficient, so the mechanical horsepower input will be greater than the water horsepower output. Lower efficiencies are due to energy losses caused by friction, leakages originating from pressure differentials within the pump case and losses due to a more complex nature.