Parallel tanks flow

[abdelperez]

Can anyone help me with this problem. I have an application where two water tanks are supplying water to a plant by the use of three pumps. Both tanks will be connected in parallel. one is a 50kgal (26 ft) the other 10K gallon (16 ft). Pumps are 100 GPM and will run one or two based on water consumption. The problem is to maintain water flow (consumption) from both tanks so water in the small tank does not become stagnant.
The plant engineers made the following suggestion.
1)placing a pressure transmitter PT1 at the 10K discharge
2)After PT1 place an orifice plate and a check valve
3)After the check valve place the tee
4) Connect the second side of the tee to a Globe modulating valve and then connect to the 50K tank discharge, place a pressure transmitter PT2 at this pipe
5) Connect the third leg of the tee to the supply pumps
and place a third pressure transmitter to this pipe.

Seems that they want to control the water flow from both tanks by modulating the control valve. Does this make sense, what will be the control variable to regulate the valve opening.

Thanks for the help

 

[quark]

If your suction pipe is short, you may not get a proper indication from the pressure transmitter. (by which you want to control the volume of water in the tanks by measuring height of water column)

We had a set up where water coming into the fire hydrant system tank(higher capacity) overflows in to main water tank(of smaller capacity). By this way we ensured no stagnation in the fire hydrant water tank. (though it is being operated for only half an hour a day)

Regards,