6 Mistakes of Centrifugal Pump Use (Part 2)
Industrial centrifugal pumps inlet attached directly to the elbow
(1) the distance between the water inlet of the water inlet pipe and the bottom and wall of the inlet pool is less than the diameter of the water inlet.If there is sediment and other dirt at the bottom of the pool, the distance from the water inlet to the bottom of the pool is less than 1.5 times the diameter, which will cause water inflow when pumping or absorb sediment debris, blocking the water inlet.
If installed in this way, the valve cannot close by itself, resulting in leakage.The correct installation method is: install the bottom valve of the inlet pipe, the next section should be vertical.If vertical installation is not possible due to topographic conditions, the Angle between the water pipe axis and the water level should be above 60°.
If the water outlet is above the normal water level of the water outlet pool, the pump head is increased, but the flow is reduced.If the water outlet must be higher than the water level of the water outlet due to the terrain conditions, elbow and short pipe should be installed at the pipe outlet to make the water pipe become siphon type and reduce the height of the water outlet.
If more elbow is used on the inlet pipe, local water resistance will be increased.And the bend should turn in the vertical direction, not in the horizontal direction, so as not to collect air.
(2) when the water inlet of the water inlet pipe is not deep enough, it will cause the water surface around the water inlet pipe to produce whirlpools, which will affect the water intake. The "skin disease" of the car will be solved in this way to reduce the water output.The correct installation method is: small and medium-sized water pump water depth should not be less than 300 ~ 600mm, large water pump should not be less than 600 ~ 1000mm.
Many QBY pneumatic diaphragm pump operators think that the lower the pumping head, the smaller the motor load.Under the misleading understanding of this mistake, the purchase of pumps, often pump head selected high.In fact, for centrifugal pumps, when the pump model is determined, the size of the power consumption is proportional to the actual flow of the pump.
Industrial Centrifugal Pumps
And the flow of the pump will decrease with the increase of head, so the higher the head, the smaller the flow, the smaller the consumption of power.Conversely, the lower the head, the greater the flow, and the greater the power consumption.Therefore, in order to prevent motor overload, it is generally required that the actual pumping head of the pump should not be less than 60% of the nominal head.
Therefore, when the high head is used for pumping water with too low head, the motor is easy to overload and heat, serious motor can be burned.In case of emergency use, a gate valve must be installed on the outlet pipe (or a small outlet can be blocked with wood) to reduce the flow and prevent motor overload.Pay attention to the motor temperature rise. If the motor is found to be overheated, turn down the outlet flow or shut down in time.
This is also prone to misunderstanding, some operators think that blocking the outlet, forced to reduce the flow, will increase the motor load, car grease in the use of several big misunderstandings.In fact, on the contrary, the normal high-power centrifugal pump drainage and irrigation units are equipped with gate valves on the outlet pipe, in order to reduce the motor load when the unit starts, the gate valve should be closed first, waiting for the motor to start and then gradually open the gate valve is this truth.
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