pumps in series: control
pumps in series: control
(OP)
I am interested to know/understand the standard control configuration for 2 pumps in series.
What i have seen is the first pump (fed from tank) has discharge valve controlled by tank level.
The second pump has its discharge valve controlled by suction pressure of the second pump.
Is it possible to control the system with only the first valve? (Someone said to me that it can't be done that way becuase the flow of the second pump wont match the first pump flow, and could result in draining the inbetween pipe- resulting in vacuum).
Of course part of the answer is that the suction pressure is controlled to prevent caviation in the second pump.
Any advice/comments?
jon
What i have seen is the first pump (fed from tank) has discharge valve controlled by tank level.
The second pump has its discharge valve controlled by suction pressure of the second pump.
Is it possible to control the system with only the first valve? (Someone said to me that it can't be done that way becuase the flow of the second pump wont match the first pump flow, and could result in draining the inbetween pipe- resulting in vacuum).
Of course part of the answer is that the suction pressure is controlled to prevent caviation in the second pump.
Any advice/comments?
jon





RE: pumps in series: control
I would not advise throttling on the first pumps with no control on the second. As you say, the second pump will potentially draw down the interconnecting line to vacuum and cavitate the second pumps badly.
Johnny Pellin
RE: pumps in series: control
RE: pumps in series: control
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: pumps in series: control
It does however sound as if your two pumps could be better matched?
Still what does the intermediate valve do? If the flow rate is too high (e.i. the discharge pressure too low) then it closes the valve - but the 2. stage pump will not see an increase in suction pressure - this it throttled in the intermediate valve - so the main function of this valve seems to be to "starve" the 2. stage pump?
Best regards
Morten