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Header tank within a recirculation system

Header tank within a recirculation system

Header tank within a recirculation system

(OP)
Newbie question, please excuse my ingnorance !

I have a water recirculation system with a pressure of 5 bar at the pump outlet and a return pressure of 3 bar at the pump inlet and an open top-up header tank before the pump inlet which by rough calculation gives a header pressure of 2 bar.

What would happen to the header tank level due to the pressures at the header/main node?

 

RE: Header tank within a recirculation system

overflow

**********************
"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/

RE: Header tank within a recirculation system

(OP)
Thanks Biginch,

What would than happen to the main circulation pump as it would now potentially be deprived of water to pump?

Would the pump return pressure drop, hence reducing the line pressure on the header, eventually finding a state of equilibrium with the header or would the header level continually oscillate ?

RE: Header tank within a recirculation system

First, your system diagram isn't really clear.  A better explanation or a sys diagram would help (see step 3 below).

All I really know is that you have an open top tank somewhere in this system and you have up to 5 bars pressure.  With an open top tank connected to the 5 bar pressure, your tank water level will be 52 meters above the pump discharge elevation, otherwise overflow.  If its connected to the 3 bar pressure, then the fluid level will be only 32 meters above the pump, still overflow if your tank can't maintain those water elevations.

Apparently your tank supplies water to pump suction, but I can't tell if your discharge recirc goes to suction, or to the tank, or if there is any orifice plate or control valve in that recirc line, or any head loss from small diameter  piping, limiting recirc flows and pressures, so I don't know how you get 3 bars at pump suction.  Is that what NPSH the tank is providing, or if you're subtracting 2 bar from 5 bar discharge pressure and its the pressure loss through the recirculation system.

If you lose inlet water, the pump will overheat and ... eventually burn.
   

**********************
"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/

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