A
Is any sensor available to sense the position (Open - close feedback & 0-100 % both) of hand operated globe valve?
Sensor to sense the position (Open - close feedback & 0-100 % both) of valve
Hello,
Some valve manufacturers have position sensors of various types; have you consulted the valve manufacturer's catalog of products?
I've seen this tried for globe valve position several times, with mixed, but usually disappointing results.
Flow through a globe valve is not proportional to valve plug position. Usually full flow through through a globe valve occurs at about 33% of "stroke", or when the valve handle is rotated about one-third of its full rotation from open to closed (presuming a uniform thread pitch on the valve stem). So it's difficult to equate valve position and flow, if that's what you're trying to do.
Since most globe valves are "rising stem" type valves, meaning the stem rises as the valve handle is turned open, you could use a linear position sensor to sense the rise, and fall, as the valve is opened or closed. The problem here is that valve stem travel (rise) is usually pretty short, so the typical linear position sensor (with, say a 4-20 mA output) wouldn't have very good resolution. To get better resolution, you would need to purchase a better sensor, and they can get pretty expensive.
So, this can be a difficult task, though not impossible--but it can be costly for a good sensor with sufficient resolution. If the valve is large, with a long valve stem travel, the sensor cost will be lower; but the smaller the valve and the shorter the valve stem travel, the more costly the sensor will be to achieve good resolution.
If all you want is open/close indication, you could use limit switches, actuated by valve stem rise/fall. There are many micro-switches which could be adapted for this purpose. But, actual position between 0% and 100% is going to be more challenging, especially if the valve is small or the valve stem travel is short.
Some valve manufacturers have position sensors of various types; have you consulted the valve manufacturer's catalog of products?
I've seen this tried for globe valve position several times, with mixed, but usually disappointing results.
Flow through a globe valve is not proportional to valve plug position. Usually full flow through through a globe valve occurs at about 33% of "stroke", or when the valve handle is rotated about one-third of its full rotation from open to closed (presuming a uniform thread pitch on the valve stem). So it's difficult to equate valve position and flow, if that's what you're trying to do.
Since most globe valves are "rising stem" type valves, meaning the stem rises as the valve handle is turned open, you could use a linear position sensor to sense the rise, and fall, as the valve is opened or closed. The problem here is that valve stem travel (rise) is usually pretty short, so the typical linear position sensor (with, say a 4-20 mA output) wouldn't have very good resolution. To get better resolution, you would need to purchase a better sensor, and they can get pretty expensive.
So, this can be a difficult task, though not impossible--but it can be costly for a good sensor with sufficient resolution. If the valve is large, with a long valve stem travel, the sensor cost will be lower; but the smaller the valve and the shorter the valve stem travel, the more costly the sensor will be to achieve good resolution.
If all you want is open/close indication, you could use limit switches, actuated by valve stem rise/fall. There are many micro-switches which could be adapted for this purpose. But, actual position between 0% and 100% is going to be more challenging, especially if the valve is small or the valve stem travel is short.
M
Mark Kretschmar
There are many questions to answer in regard to what you need from the sensor. Lion Precision has done some pretty advanced work in this area, but probably more than you're looking for.
http://www.lionprecision.com/corp/news-2010/10-08-31Nasa.html
You'll need to be more specific about where you want to mount the sensor and throw of the shaft.
http://www.lionprecision.com/corp/news-2010/10-08-31Nasa.html
You'll need to be more specific about where you want to mount the sensor and throw of the shaft.
