Why water pump must install check valve？ Wroten by TDRFORCE Water Pump Factory or Manufacturer
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Description:Why water pump must install check valve？ Let's follow the guide from TDRFORCE Pump Factory or Manufacturer.
Why water pump must install check valve？The Pump Tech From TDRFORCE Water Pump Factroy|Manufacturer?
Water pump without check valve consequences: water in the water pump outlet pipe due to valve opening, valve closing and pump stop sudden change, resulting in a sudden change in the flow rate in the pipe, resulting in a change in momentum per unit time, the corresponding inertia force is inevitable, resulting in the pipeline pressure rise and sudden drop of alternating change phenomenon.This phenomenon of water velocity and pressure changing with time and position is called water hammer (or water hammer).
The water hammer of the pump station includes the starting water hammer, the valve closing water hammer and the pump stopping water hammer (formed due to sudden power failure and other reasons).The first two types of water hammer do not cause any safety problems under normal operating procedures.The latter form a water hammer pressure value is often high, resulting in accidents.The purpose of studying water hammer and calculating water hammer is as follows:
- To formulate protective measures when the maximum water hammer pressure causes damage to pipes and units;
- To formulate the minimum water hammer pressure in the pipeline caused by the negative pressure is not allowed, and lead to the damage to the pipeline protective measures;
3) to prevent the damage caused by unit reversal.In the pumping unit system, the characteristics of the pump is for pipe line boundary conditions at the end of the beginning, now we analyze the pump export don't install the check valve, pipe exports also no door, stop the pump when the accident, lose drive pump, pump discharge side gate valve does not close in a timely manner, pipeline internal waters when backflow of water hammer process (or) hydraulic transition process.
Consequences of water pump not installed check valve:
When the pump loses power, the speed of the pump drops sharply. The water flow in the pump and outlet pipe continues to move in the original direction due to inertia, but its velocity decreases rapidly and the pressure drops until the water flow stops flowing in the positive direction and the flow rate is zero.At this moment, the pump is still positive, and the water flow is positive (the water movement from the pump to the direction of the pool is called positive flow), which is called the pump working condition.
2, braking mode In the transient static water bodies of water flow rate is zero, because of the effect of static head, the outlet pond and a water pipe produced by reverse flow of water out of the pool to the water pump flow, reverse flow, is still in the forward to play the role of a brake pump impeller, unit force of rotor speed accelerated decline, until the engine speed is zero.At this moment, due to the resistance of the positive rotating impeller against the countercurrent, the pump outlet pressure gradually increases, and the transient working condition of the pump at this moment is called the braking working condition.
3, turbine working conditions with the increase of the reverse flow, the pump speed from zero to reverse, and rapidly rising, at the same time, the rotating impeller on the flow of centrifugal force also increases, the reverse flow plays a role.This resistance increases with the acceleration of the impeller reversal, so that the pressure after the pump rises rapidly, reaches the maximum at a certain moment, and the corresponding reverse speed also reaches the maximum.
When the resistance increases, it also counteracts the continuous increase of the reverse flow rate, and gradually decreases after reaching a certain maximum.Less effect on the impeller of energy, make the reverse speed decreases gradually, until the stable under the action of static head, the water flow in the impeller on the parts of the torque and turning resistance moment balance, the unit at a constant reverse flow rate and rotational speed under the condition of no load work like turbine, water hammer pressure disappear.
This transient condition is called turbine condition.The above is the consequence that the pump does not install check valve, at the same time, the pressure change after the pump will be in the form of water hammer wave along the outlet pipe to the outlet pool is shot, and then reflected back from the outlet pool, the formation of complex water hammer phenomenon in the outlet pipe, waterproof hammer check valve products can be used waterproof hammer check valve.