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Effect Of Low Flow At Pump Suction


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#1 sargon 1979

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Posted 26 May 2021 - 11:30 AM

Dear all;
2 booster pumps are feeding one main pump. What will happen if one booster pump is tripped?
Thank you in advance

Edited by sargon 1979, 26 May 2021 - 11:30 AM.


#2 Chemitofreak

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Posted 26 May 2021 - 02:29 PM

The pumps are in series.

 

1. If the 1st pump trips and the 2nd is still running there might be cavitation issues in the 2nd pump (generally called as booster) again that depends on the line loss in the suction of the 2nd pump, if there is no suction line loss issue, then it will reach the shutoff head as it cannot develop the required head.

 

2. If the 2nd pump trips then the 1st pump will then reach the shutoff head as it cannot develop the required head.

 

   



#3 sargon 1979

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Posted 26 May 2021 - 03:40 PM

Dear Chemitofreak
Suppose that two booster pumps capacity of 25 m3/hr each are feeding a main pump capacity of 50 m3/hr. What will happen to the main pump if one booster pump is tripped? If one booster pump is tripped then the suction pressurue will not be affected but the Flow rate is reduced to 25 instead of 50 m3/hr. Thank you and Please clarify

Edited by sargon 1979, 26 May 2021 - 03:44 PM.


#4 fallah

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Posted 27 May 2021 - 12:12 AM

Dear all;
2 booster pumps are feeding one main pump. What will happen if one booster pump is tripped?
Thank you in advance

 

To get a proper reply please upload a simple sketch of the pumps system you described...



#5 Chemitofreak

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Posted 27 May 2021 - 01:42 AM

Dear Chemitofreak
Suppose that two booster pumps capacity of 25 m3/hr each are feeding a main pump capacity of 50 m3/hr. What will happen to the main pump if one booster pump is tripped? If one booster pump is tripped then the suction pressurue will not be affected but the Flow rate is reduced to 25 instead of 50 m3/hr. Thank you and Please clarify

 

Hi,

 

The booster pumps are pump pumps in parallel, the booster pumps with the main pump are pumps in series. 

 

If one of the booster pump trips, the over all flowrate of the system will be reduced i.e. it will be 25 m3/hr, because in pump in series configuration the flow is limited by the pump having lesser capacity  



#6 sargon 1979

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Posted 27 May 2021 - 04:49 AM

Thank you fallah but in case of one booster pump is tripped, is there any damage or harmful effect on the main pump?

#7 Chemitofreak

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Posted 27 May 2021 - 01:50 PM

Thank you fallah but in case of one booster pump is tripped, is there any damage or harmful effect on the main pump?

 

Every centrifugal pump must run at a flowrate above the minimum recirculation flow or else the pump will be damaged. 



#8 sargon 1979

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Posted 04 June 2021 - 11:22 AM

Dear Fallah;

Suppose that the minimum flow is determined to be 12.5 m3/hr for the main pump which gives 50 m3/hr at rated head. Since the main pump is fed with two booster pumps (capacity of 25 m3/hr each) then when one booster pump is tripped the total flow of the main pump is suddenly reduced to 25 m3/hr without reaching the minimum flow (12.5 m3/hr).

 

In this case; Is there any anticipated damage to the main pump?

 

Thank you



#9 fallah

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Posted 04 June 2021 - 12:11 PM

 

Suppose that the minimum flow is determined to be 12.5 m3/hr for the main pump which gives 50 m3/hr at rated head. Since the main pump is fed with two booster pumps (capacity of 25 m3/hr each) then when one booster pump is tripped the total flow of the main pump is suddenly reduced to 25 m3/hr without reaching the minimum flow (12.5 m3/hr).

 

In this case; Is there any anticipated damage to the main pump?

 

 

Hi,

 

With the info you provided, appears when one of the parallel booster pumps is tripped no damage to the main pump is anticipated especially because we know single operating pump will deliver more flow than the same pump when operating in parallel; i.e. the single booster pump probably will deliver more flow than 25 m3/hr.






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