Split Range Controller Output

Dear Latexman

I have  a Temperature control valve installed in a 50% propylene+glycol and water line, used to heat Boil off gas coming from a compressor at -190 ^oF. 

1,300 lb/hr of Boil off gas (99% Methane) is heated from -190 ^oF to -10 ^oF.  The 50% propylene glycol is coming in at 90 ^oF and going out at 80 ^oF.  The flow rate of GW is 16,000  lb/hr.

A temperature control valve is installed in the Glycol water line coming into the shell and tube exchanger (attached sketch). which senses the Outlet temperature of the glycol water from the exchanger and sends the required amount. 

Please let me know how to set the controller output for the temperature split range for 4-12 mA, 12-20 mA.

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Please let me know what other information is required to get the controller output.

Nivedita 

Try this link to learn more: https://www.instrume...control-in.html

I believe the location of the mix point is incorrect in the diagram you have shared.  The Exchanger bypass stream should mix at upstream of TT-TIC, for proper control.  Revert in case doubt persists.  Remember one is Fail Open and the other is Fail Closed Valve, so signal multiplier with inverted signal to be used.

Regards

Bodhisatya.