Control valves, or pressure regulating valves often generate high levels of noise that can be a danger to nearby workers, or disturb nearby residences. If these high noise levels are not designed out prior to installation of the equipment then site remedial measures will be limited to acoustic cladding or acoustic enclosures.
The noise levels at these valves will usually be at its worst when there is a high flow rate and a high pressure ratio across the valve. However, it is not always the case that when the valve is turned down and the flow rate is low that the noise level reduces significantly. Noise levels from control and pressure regulating valves will typically be between 90 to 100 dB(A) at 1 metre from the valve, but at their very worst they may reach 115 dB(A).
There are many ways to solve this problem, from expensive quiet trims for the valves, to splitting the flow into multiple streams.
Flo-Dyne's answer to this problem is to provide a purpose built in-line silencer that will attenuate the noise emmited by the control valve or regulator and prevent it from entering the downstream line to be re-radiated.
This purpose built silencer will usually, but not always, comprise of a drilled diffuser and an absorptive baffle. In cases where there control, or pressure regulating valve is limited has a capacity limit then the silencer will be supplied without a diffuser.
When included, the inlet a diffuser, will provide back pressure onto the upstream valve (within its capacity limit) to reduce its pressure ratio and therefore noise. The diffuser is immediately followed by an absorptive baffle pack which attenuates the remaining noise to achieve the required outlet sound level.
Both of these components, the diffuser and the acoustic baffle, have been proven in thousands of Flo-Dyne silencers and so we are able to deliver guaranteed noise levels, pressure drops and flow capacity.
The construction of the acoustic baffle will be from materials that are compatible with your process and will not degrade or be lost from the silencer over time.
The whole silencer will be built to be part of your piping system and with construction either as a pressure vessel to a construction code, such as ASME VIII, or a piping code such as ASME B31.3.
CE marking will be applied as standard to equipment destined to be used inside the European Union.
Where noise levels below 85 dB(A) are required it is often necessary to install additional measures to reduce the noise radiated by the body of the silencer, and/or the body of the valve.
Acoustic cladding can be used for this purpose, however simple acoustic cladding systems often deteriorates with time as they are repeatedly removed and replaced for inspection and maintenance purposes.
Where control valves and pressure regulators have high flows and high pressure ratios, noise generated inside the valve can travel against the direction of the flow and propagate into the upstream, or inlet piping.
In such cases a silencer, without a diffuser, and just comprising of the acoustic baffle is necessary to stop the noise. However, where inlet silencers are considered necessary it is not unusual to find that the local noise level around the control valve or regulator is too high and that silencers alone, although stopping the noise getting into the connected pipework, do not sufficiently treat the noise around the valves themselves.
Where silencers alone are not considered sufficient to reach the noise level required Flo-Dyne can supply robust acoustic cladding that is of welded construction, shaped to fit the equipment and bolted in position, such that the fit, quality and performance of the cladding system will not deteriorate with time.
This combined approach using an inline silencer and high quality, robust acoustic insulation system will reliably deliver residual noise levels under 80 dB(A), without deterioration.
