Eddie-GH

Pl give the following information , which could help me to think in the right direction for troubleshooting your problem.

1) HOw much is the distance between the Custody transfer meter skid & Customer receiving end.

2) On what basis these control valves are working ,Ie Are these flow control valve or pressure control valve or anything else? ( Whats the set point for the controller of these valves -- flow or pressure ).

3) If u can give PID drawing about your process , then it would be the best to understand all the possible reason for the drop in the pressure.

4) There could be many possible reason for this drop in pressure , such as One of the valve , either custody side or receiving side is malfunctioning , Check for the smoth operation of the control valve.

5) Check all the instrument wiring connection between the control valve & its controller for any loose connection , which incidentally may cause the valve to close etc.

There are many many possible reason , you have to start troubleshooting one by one right from loose connections in the wiring , mechanical operation of the control valves , operation philosophy of the control valves ( Pressure or flow ), Improper tuning of the controller etc.

hi Eddie ,

what I feel is the opening of the control valves

when at night customer side load increases the rate of opening of the valve increases and at the same rate should be increased at your end if there is a mismatch in rate of opening this can cause to drop in pressure, ie the opening of your end valve is slow than the customer end opening .

try to tune the controller at your end make little faster in order to reduce the lag .

Regards

Adil