I have 2 tanks of same product, while the other is being filled the other will stand still and once the filled one is full the product will be switched to the empty one and the full one will the transfer to the store tank once it has been analysed. The project is to ensure that this two are not contaminating the store tank. Let only the transferring transfer to the store tank.

There are valves installed but this tanks share the one pump, so mistake do happen where the tank that is being filled get to transfer to the store tank which then contaminate the store tank.

How can I use the level transmitter alarm to alert the control room that now the Filling tank is transferring. Hint: I don't want to use control valves as they are costly and the level transmitters are already installed so I want to use the already available resource.

Please Help.

[email protected]

 

Assuming you have a valve at each tank to select which one is delivering product put a position switch on the valve. With a similar switch on the fill valves interlocked to the delivery pump it should be easy to interlock so you can only deliver to an off line tank.

 

Well, first of all you need to identify WHY mistakes happen. If contamination is a problem, then trying to use a level transmitter to detect small changes in level won't solve your problem - it will only tell you that you've contaminated your final product tank again. And that is assuming that your level measurement is sensitive enough, accurate enough and fast enough to alert you to the problem in time.

Do your valves have open & closed limit switches to confirm their position ? If not, they almost certainly should have. Is the problem in your HMI - i.e. are operators incorrectly selecting the tank to transfer ? Is your control logic correct, or is there some situation where the wrong tank can get selected ? And most importantly, what is the cost of a contaminated batch compared to the price of some extra instrumentation and actuators ?

Rob
www[.]lymac.co.nz

 

Thanks for your support, this seem to be the way forward to me.

I do have a selection valve which is the suction valve which each tank has it's own valve. The suction of the tank to transfer will be open and the other tank will close only the rundown valve will be open. The delivery line from the pump is directly to the store tank where it should transfer.

Is it possible for me to put the position switch to both suction valves, and who the position valve will close the flow from the rundown tank?