High performance butterfly valves

[carlo1023]

From my understanding, high performance butterfly valves only include double offset and triple offset butterfly valves. Concentric butterfly valves are not high performance butterfly valves. Is this correct?

Also, butterfly valves having an offset design cannot be lined. Is this understanding correct? I haven't bought any butterfly valve with offset design that has a lining on it.

 

[gerhardl]

Others will probably give additional comments,but

1. In my understanding 'high performance' is a common, often used by factories, description of valves with extended ability to keep thight at higer temperatures and pressures than more common 'standard valves'. I do not know of any standard describing the difference between a common/standard valve and a High Performance valve. High-Performance tends to be a 'factory description' for chemical and petrochemical branches. Loosely the boundary will be where a standard BF centric valve will not function properly, for common smaller sizes perhaps somewhere between 16 to 25 bars. Typical a high performance valve will, as you state, be a double or trippel eccentric construction, with metal to metal seats and at least at 25 -40 bar performance, even if the construction and flanges could be used or certified for lower pressures.

2. Double eccentric valves are well-known both with linings and soft sealings. For instance for drinking water or hydroelectric plants, up to higher pressure classes ( at least 40 bar). Sizes will range from 50mm to 2000mm and more. Temperature range for fluid is normally limited. The valves will not be called or marketed as high-performance valves.

 

[bcd]

The term "high performance" was created when the offset shaft designs were first created back in the 1960's. With the offset shaft, a solid shaft of high strength material could be used which increased the pressure rating of the valve. Also, the offset shaft improved the cycle life of the seat, so the valves lasted longer than the concentric type. Higher pressure rating and longer life was put together into one term, "high performance".

 

[TOVmania]

#1 Comment: You are right.
#2 Comment: Double Offset BFV can be lined as well.