Tham khảo tài liệu 'know and understand centrifugal pumps episode 8', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Know and Understand Centrifugal Pumps Second one single pump operating to the right of the BEP indicates that the pump will consume more energy and may require a more powerful motor. For example if two parallel pumps running together consume 19 horsepower BHp of energy it would seem natural to install a 10-Hp motor on each pump where the individual consumption would be horses each. But operating one pump to the right of its BEP indicates that this pump might consume 11 or 12 horsepower. Therefore it might require a 15 horsepower motor installed for running solo. Operating together the two parallel pumps will only burn horses each for a total of 19 BHp. The solution is Be prepared to step-up the horsepower on the motor of one solo pump in a parallel system. Third you would suppose that parallel pumps are identical that they were manufactured and assembled together. But it is possible that one pump of the pair is the dominant pump and the other is the runt pump. If you start the dominant pump first in the parallel system and then decide to add the runt pump of the pair the weaker pump may not be able to open the check valve. The pump operator perceives that the flow meter on the second pump is stuck or broken. This is because the second pump might be dead heading against a closed check valve maintained that way by the dominant pump. If this situation exists it may result in premature failure of bearings and seals leading maintenance and operations personnel thinking that parallel pumps are problematic. The solution is Identify the dominant and weak pump should they exist. To do this take pressure gauge readings with the pumps running at shut-off head. Verify that the impellers arc the same diameter and that the wear bands and motor speeds are equal. If you can identify one pump in the pair as dominant always start the weak pump first and then add the dominant pump in parallel with the weaker. The dominant pump coming on stream will push open the check valve.
