Shh... don't make a noise about it
15 Jan 2000
As the main text shows, valve and actuator manufacturers are making a big noise about 'smart' devices. But how much noise do control valves themselves make? In extreme cases, the answer is a hell of a lot. It can damage operators' hearing, not to mention the effect on the neighbours. And it can also be a warning of valve instability and pipeline vibration that can shorten equipment life.
Last month, though, Fisher Controls made the right sort of noise when it launched its WhisperFlo trim for high duty control valves. Claimed to achieve up to a 40dBA reduction in aerodynamic noise caused by a control valve operating under severe service conditions of high pressure drops and high flow rates, the WhisperFlo is some 25-30 per cent better at noise attenuation than conventional trim designs.
The innovative design is based on laser-machined discs which are stacked and permanently fused into a rigid cage assembly. The stack is precision honed to fit into standard Fisher globe valve designs.
The trim combines, for the first time in one design, six key noise control techniques: multistage pressure reduction; reduced acoustical conversion efficiency of each stage; frequency spectrum shift; exit jet independence; velocity management; and complementary body design.
According to Fisher, the WhisperFlo delivers predicted noise levels consistently, avoiding the cost of recalculating and retrofitting valves to meet expected performance levels.
