Hi All
Customer had put me in a some what difficult scenario. I am working at a Gas plant which has lot of fishercontrol valves (D2 or L2 etc). Most of these valves are bench set at 14 to 30 psi (14 to start open and 30 to fully open). Their respective I/P are set at 6 to 30 psi....so with this difference there is a delay of opening these valves...around 40% plc output. But when they are open then they tend to control fine.....Customer has already made his mind that they need positioners.....and he wants me to suggest him to install positioners on these valves.
According to me, they do not need positioners...i know positioners will help to make the opening and closing of the valve faster....but if the process is not stable and we see huge swing in temperature of reboiler from 140 to 170 degree F even the valve is Snap shut.......then even positioner under these circumstances will do nothing.....
What you guys suggest.....do we really need positioners to install.....even though valves are controling just fine (except the initial start)? When the valves are in the range of 40 to 70 % they throttle great.
Your input on this will highly be appreciated and will able to guide my customer in a better way.
Customer had put me in a some what difficult scenario. I am working at a Gas plant which has lot of fishercontrol valves (D2 or L2 etc). Most of these valves are bench set at 14 to 30 psi (14 to start open and 30 to fully open). Their respective I/P are set at 6 to 30 psi....so with this difference there is a delay of opening these valves...around 40% plc output. But when they are open then they tend to control fine.....Customer has already made his mind that they need positioners.....and he wants me to suggest him to install positioners on these valves.
According to me, they do not need positioners...i know positioners will help to make the opening and closing of the valve faster....but if the process is not stable and we see huge swing in temperature of reboiler from 140 to 170 degree F even the valve is Snap shut.......then even positioner under these circumstances will do nothing.....
What you guys suggest.....do we really need positioners to install.....even though valves are controling just fine (except the initial start)? When the valves are in the range of 40 to 70 % they throttle great.
Your input on this will highly be appreciated and will able to guide my customer in a better way.