Centrifugal pump is started outlet valve should be closed? - - - - - -
a lot of matters need attention when start centrifugal pump, but when start centrifugal pump outlet valve should be closed? Let's get to know each other:
why centrifugal pump outlet valve should be closed when start?
centrifugal pump starts, there is no water in the pump outlet piping, so there is no pipe resistance and lifting height of resistance. Centrifugal pump starts, the centrifugal pump is very low, traffic is very big, the water pump motor ( Shaft power) Output is very big, According to the pump performance curve) , it is easy to overload, it will damage the pump motor and the pipe. Therefore, must be closed when starting the outlet valve to make the normal operation of pump.
if you use the axial flow pump, the reverse is true. Have to start by opening the valve. At this time, due to a short period of time without resistance, power of the motor will be too much traffic. vibration, noise, and even motor overload operation will often happens, motor burn out. Close the outlet valve is equal to the artificial setting pipe resistance. After the normal operation of pump, slow start valve, make the pump performance curve in accordance with the rules work step by step.
before start centrifugal pumps, must ensure that the 2 points:
1. Filled with water pump shell, in order to form a vacuum;
2。 The gate valves must be closed on the outlet pipe to avoid formation water pump flow, so that we can reduce the starting current of motor start steady in favour of the pump. As the water pump start steady, gate valve should be opened slowly.
rely on centrifugal pump impeller of the centrifugal force to form a vacuum suction to carry water. Therefore, when the centrifugal pump, must turn off the outlet valve to water injection. When the water level exceeds the impeller position, only when the air out of centrifugal pump, centrifugal pump to start. After start-up, vacuum formed around the impeller, sucked up the water, automatically open and litres of water. Therefore, you must close the outlet valve.
about centrifugal pump
a centrifugal pump is a vane pump. In the process of the rotation of the rotating impeller, due to the interaction between blades and liquid, blade pass mechanical energy to the liquid, thus increasing the pressure of the liquid, to achieve the purpose of conveying fluid. A centrifugal pump has the following characteristics:
1) head of centrifugal pump in a certain velocity has a limit value. Working point flow and are connected to the pump shaft power depends on the conditions of the equipment system ( Electric potential difference, differential pressure and pipe loss) 。 Head changed to flow.
( 2) Running is stable, continuous transmission, flow pressure pulsation.
( 3) In general, there is no self-priming ability, before starting work, need to vacuum pump needs to be filled with fluid or pipes.
( 4) Centrifugal pump discharge pipeline valve closed when starting, when the axial flow pump and vortex pump start valve fully open, in order to reduce the starting power.
before starting the pump, pump shell of conveying liquid; Starts, driven by axis high-speed rotating impeller, the blade between the liquid must spin. Under the action of centrifugal force, the liquid from the impeller center was thrown to the outer edge and gain energy, in the impeller outer edge leave volute pump shell enter at a high speed.
in the volute, liquid due to a gradual expansion to slow flow channel, can and will be part of the kinetic energy is converted to static pressure, static pressure can eventually by higher pressure into the discharge pipe, and was sent to the desired location. When liquid flow from the impeller center to edge, the impeller center will form a certain vacuum. Due to the liquid level in storage tank above the entrance pressure, the pressure is greater than pump fluids are continuous pressure into the impeller. Obviously, as long as the impeller to rotate, the liquid will be overtaken by suction and discharge.
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