Characteristics for triple offset butterfly valve

[valvecontrol]

is it suppose to be Equal percentage?

Thanks,

 

[JLSeagull]

Offset butterfly valves address butterfly valve seat and stability issues. The equal percentage characteristic is easily machined into a globe valve plug or cage. A butterfly is more linear through the middle travel, likely quick opening at the beginning and perhaps the end of travel. You may be able to characterize a valve with a smart electronic positioner; or cams on a mechanical positioner. Fisher provides lots of capacity data. Use the Fisher butterfly valve data and draw some curves.

 

[NGiLuzzu]

The curves of triple offset valves usually may be considered about halfway between equal percentage and square root characteristics... resulting in a linear behaviour (and therefore a good rangeability) far from the complete opening and closing positions, i.e. approx. in the 20°÷70° or 20%÷70% range.

For more specific information, of course, refer to the Manufacturer.

Hope this helps, 'NGL