Balance Drum Working in Centrifugal Pump

Hi

due to pressure difference across the pump there is always thrust on the rotor toward suction side of pump due to fluid .So to balance this thrust

these are methods to balance the thrust

1. First is balancing drum

balancing drom is cylindrical portion installed on the rotor of the pump generally at the discharge end side.small gap in mm is maintained axially betweel casing or dummy piston which is stationary part attached with pump casing.

one side of balancing drum, pressure=discharge pressure

another side of balancing drum, the pressure =suction pressure (slightly greater than suction pr. which is maintained by a balancing line connected to suction line of pump.so due to pressure diff. across balancing drum there is thrust which will opposite to the thrust created by fluid and will be approx 90% of it. rest 10% of thrust is born by thrust bearings.

similarilly case of balancing can be understood.

diffrence is only in b.drum axial gap is maintained but in balancing disc radial gap is maintained.generally b.drum is used for steady flow operations ,otherwise there will be variable loading on gland packing or mechanical seal,whereever variation in operation then disc is used

but to get benefitted with both type combination also available

for BFW pumps etc