( 🔴 ) Link to FREE Udemy Course for I&C Professionals

1500+ Engineers have taken the Course
(Engineers have said it is even BETTER than the PAID Courses available)

Give it a Try 😊

https://asad-shaikh-instrumentation.c...


A pressure-balanced trim uses the process pressure to balance the static pressure acting on it, while unbalanced trim takes the full force of the process fluid.

Unbalanced trim: There is no balance hole on the plug, the medium pressure differential acts on the effective area of the plug to generate a force equal to the product of the differential pressure across the plug and the plug’s area (F = PA). However, balanced plugs do not generate this same force because they equalize the pressure on both sides of the plug.

Unbalanced trim control valves are suitable for applications where the pressure difference is not large.

Balanced trim control valves are suitable for applications with large pressure differences.

You can learn more about these in the below technical paper by Valtek

https://pro-quip.com/images/proquip/P...

Unbalanced trim design generally requires that the direction of flow should assist the motion of failure, for example, flow-over for fail-closed and flow-under for fail open.

Pressure-balanced trim design generally requires that the direction of flow be opposite to standard (unbalanced) trim to oppose the motion of failure for example, flow-over for fail-open and flow-under for fail-closed