discharge valve control

varunmahendran91 · Oct 3, 2014

Hi all,
I have 4 indications for a discharge check valve, are,
1-fully opened indication
2-fully closed indication
3-open control
4-close control
but haven't any position indication.i have to start another condition when valve reaches 95% of its closed position. can anyone of you help me?

osmanmom · Oct 3, 2014

software or hardware ?

Tom Jenkins · Oct 3, 2014

First, I don't think you really have a check valve. They tend to not have controllable position.

Most motor operated valves can be supplied with a potentiometer that can be installed on the operator or the valve stem. This in turn can be wired to a signal conditioner and into your controller.

Most also have the ability to add additional limit switches. That's not as convenient but may suit your purpose. Contact the valve operator supplier.

varunmahendran91 · Oct 3, 2014

First of all thanks Tom.
Actually they had given limited spec for the programming section and they haven't described about any position indicator or potentiometer.i am a beginner in programming.we are doing this program without having any clear idea about the field and field instruments.

varunmahendran91 · Oct 3, 2014

Software

osmanmom · Oct 3, 2014

what model of discharge check valve ?

varunmahendran91 · Oct 3, 2014

what all i understood from the given spec is, that one is a motor operated check valve.they didnot give any product specification.at the 95% of it closed position the motor assosiated with that valve stops.

osmanmom · Oct 3, 2014

without spec info or others info the answer will be general answer.

or at least manufacture name.

shooter · Oct 3, 2014

Put one of the control switches to change position at 95%, here you can act on it.

Lancie1 · Oct 3, 2014

at the 95% of it closed position the motor assosiated with that valve stops.

Is this the air valve for a fuel-air burner control valve? Probably you can move the "fully closed" limit switch so that it operates at 95% closed instead of 100% closed. That is about the minimum setting for many air valves on a fuel-air valve pair.

That is about all you can do, unless you have some other analog input that tells you the position of the valve.

If accuracy is not critical (+/- 10%), then you could start a timer when the "CLOSE" signal is given. Then manually read the timer when the valve is 95% closed. Then set the timer for this value. Then each time thereafter, when the timer is done, the valve should be about 95% closed.

varunmahendran91 · Oct 4, 2014

Thanks Mr. Lancie1, but there is no option for reading its position manually since we are doing US(distant) projects. is there any other way to calculate approximate position other than this time calculation or flow measurment?

Lancie1 · Oct 4, 2014

Sorry, I don't know of any other way except adding a physical limit switch that operates when the valve is 95% closed.

You need to explain the importance of this 95% Closed position, and how it is different from 100% closed. Do you have to have the 100% closed indicator? If not, then if it is adjustable (most are), then adjust if back to 95% closed, and you are done.

meghnesh · Oct 4, 2014

Hi....just check the terminal connections for the valve.
If it does not have any connections for Analog i.e the Potentiometer, usually 0-100 Ohms...it means your valve is not equipped with a positioner.
Alternatively, not a recommended suggestion... create a Logic or Function Block in the PLC showing the Position of the Valve depending on the transit time from Open to close...

GTUnit · Oct 4, 2014

varunmahendran91 said:
First of all thanks Tom.
Actually they had given limited spec for the programming section and they haven't described about any position indicator or potentiometer..

This is unacceptable.
Yet typical of many customers. They just want you to make it work without any clear details of what you are controlling.
Completely unacceptable.
You need to go back to the customer and demand the exact model numbers of the field instruments or you will be very miserable in the near future.
Ask me how I know.

varunmahendran91 · Oct 5, 2014

thanks all, for ur ideas and comments

discharge valve control

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