Chilled Water Pump : Flow Rate 1

[elninho971]

I'm quite new in this field. I have a question to ask someone who can explain or suggest me about my problem below;

I have 4 Chillers & 4 Chilled Water Pumps at my plant, they are designed at the same flow rate 2000 LPM ( 1 CHP/ 1 Chiller). the suction & discharge pipe size for each unit is 6" and connect to 10" header.
Nornally, I run 2 or 3 units per day (depend on load), there are no problem. However, if I try to only 1 set ( 1 CHP & 1 Chiller ), the CHP will roar. If I run the 2nd set, the roar will disappear.

is possible that sound are occurred by the flow rate from 1 set is not match to the 10" header?

Thank you in advance for your help.

 

[Artisi]

It would appear that when you run only 1 pump there is insufficient head against the pump - it runs out on its curve and cavitates. A quick check for this is to throttle the pump discharge (if possible) this will increase the discharge head and the pump will move left along the curve and away from the area of cavitation.

 

[elninho971]

Thank you so much, Artisi.

I've tried as your suggest and there are no more roar anymore.

Thanks again.

 

[SAK9]

Rather than manually fiddling with the pump discharge valve,you could install an automatic balancing valve(check with Flowcon)on each pump outlet or chiller outlet.The valve will self adjust to maintain preset flow and will never go into the runout condition you were experiencing.