Loop Tip – Checking Your Control Valve’s Deadband

In his continuing series of Loop Tips, John Egnew, a training consultant and instructor for Emerson’s Educational Services group discusses the impact of final control element deadband on loops.

His Loop Tip #8: A Chance For Stardom, discusses the case when some loops prove to be difficult to tune, no matter what algorithm is used. He recommends you look at the control valve’s deadband which is typically caused by friction and lost motion. John states:

This friction from valve packing, seals, or process buildup can cause valve deadband to be at least 5%.

Adding a positioner can help reduce this deadband to less than 1%. If you get the deadband to a reasonable level, then you can apply tuning based upon the dynamics of the loop.

In the Education category of this blog you’ll see quite a number of posts recommending the best way to approach this tuning, including some of John’s excellent tips.

Posted Monday, November 13th, 2006 under Education.

One comment so far

Leave a Reply