Function of the DN40 bypass lines at the inlet and outlet of the high-pressure boiler feed water pump (multi-stage centrifugal pump)
Thread Content
Each high-pressure boiler feed water pump (multi-stage centrifugal pump) has a DN40 bypass line at both the inlet and outlet, and the bypass line valve is a globe valve. Is it necessary to turn on this bypass line when starting the pump? Could it cause high pressure to be transmitted to low pressure, resulting in damage to the impeller? Additional note: There is already a DN80 return pipeline from the total export to the deaerator.
This DN40 pipeline is likely the minimum flow return pipeline, designed to ensure that the pump can operate properly when the flow rate is below its minimum value. The minimum flow valve is activated when the flow rate falls below this minimum level, thereby preventing damage to the pump. If the return line from DN80 to the deaerator cannot function as a minimum flow return line, it is recommended to open the minimum flow valve when starting the pump.
It’s best to take a photo; if it’s a balanced return pipe, this pipe is necessary and no valves should be installed on it.
It is certainly necessary. When switching the high-pressure boiler water pump, first slightly open the bypass line of this standby pump. To prevent the outlet line pressure from becoming too high when two pumps start simultaneously. Leave a slight gap usually. It is used to adjust the outlet pressure of the pump. Because the branch line leads to a place with lower pressure. With the slightest movement, the pressure of the pump changes significantly
Which brand is good for multi-stage centrifugal pumps used in boilers?