ANSI Class 6 standard origins? 2

[carltogr]

Hello everyone,

On a recent search for PVC butterfly valves, I noticed that most companies refer to ANSI Class 6 shut-off as criteria for valve quality. I need to know what ANSI Class 6 shut-off means, and how the valve is built/tested to meet this criteria. What standard does the ANSI Class 6 classification originate? I looked on the ANSI site, and throughout the web, but can't seem to find it. Anybody have a clear definition of ANSI Class 6, and a source to refer to?

 

[RubenJ]

ANSI has 6 classes to classify valve leakage performance, where Class I is the least strict and Class VI is for the tightest.

Class I requires no testing while Class VI requires that leakage throught the valve don´t exceed certain amounts depending of the size of the valve, Test is made with air or nitrogen and a differential pressure across the valve of 50 psig or max rated pressure wichever is lower.

 

[jsummerfield]

Depending upon the control valve capacity, ANSI Class V can be tighter than Class VI as the measurements differ. These are control valve leakage classes -- NOT Shutoff Valve leakage classes. If you look at the standard you will see FCI, the name of the organization that originated the standard. I think that the F was for Fluidic or Flow, C for Control and I for Institute.

John

 

[NGiLuzzu]

The reference standard for control valves leakage classes is FCI-70-2 (previously named "ANSI B 16.104"; latest revision: 2003) or equivalent IEC 60534, Part 4, Amendment 1.

Please take also a look, within this Forum, at:
- Thread408-23297;
- Thread408-45258;
- Thread174-76111 and Thread408-76110.


Hope this helps, 'NGL