CONTROL VALVE NOISE
CONTROL VALVE NOISE
(OP)
Hi,
We got a quotation for a 24" butterfly conrol valve (to be installed on a 28" line splitter overhead) with a predicted/calculated noise level of 105 dBA.
Can this noise level also cause mechanical damage beside health incidence?
How can we lower this noise level?
Is there any correlation between the calculated noise level to measured noise level after installation and operation of the control valve?
regards,
roker
We got a quotation for a 24" butterfly conrol valve (to be installed on a 28" line splitter overhead) with a predicted/calculated noise level of 105 dBA.
Can this noise level also cause mechanical damage beside health incidence?
How can we lower this noise level?
Is there any correlation between the calculated noise level to measured noise level after installation and operation of the control valve?
regards,
roker





RE: CONTROL VALVE NOISE
there are 3 basic types of noise sources in valves:
1) mechanical vibration
2) cavitation
3) aerodynamic noise
Noise is bad for your health and valve's health. What method was used for predicted/calculated noise level? Please refer to ISA S75.17 for a fairly accurate prediction method.
OSHA limit for noise level is 90 dB. Even if you ignore OSHA then anything above 110 dB is dangerous for equipment and personnel safety.
There are ways to reduce noise, like:
1" thick pipe insulation will reduce noise 5 to 10 dB
If you double the pipe thickness it will reduce around 5-6dB
Silencer downstream will cut it by 10dB
Silencer up and down stream will give you 20 dB reduction
Multiport resistance plate down stream will cut it 15-20 dB
Special low noise valve for 15 - 30 dB
of course you can apply a combination of the above methods, which is sometimes more cost effective.
RE: CONTROL VALVE NOISE
If this noise is from vibration or cavitation, then the noise is a byproduct of potentially destructive forces.
Regardless of the source of the 105dBA noise, in the USA engineering controls are required if practical. Khan101 gives several likely options to address noise sources.
Best of luck, sshep
RE: CONTROL VALVE NOISE
Health risks? Yes.
SPL calculations work fine as lone as you include the line noise but they do have limitations; such calcs are not an exact science given the number of variables.
Reduce the noise? It all depends on how the noise is generated. Lagging is not always the best cure.
Good luck,
RE: CONTROL VALVE NOISE
For a globe valve in the six-inch or smaller category I would assume mechanical damage around 115 dB. Check with the manufacturer. Howver, 105 dB seems potentially damaging for a 24-inch butterfly.
John
RE: CONTROL VALVE NOISE
RE: CONTROL VALVE NOISE
Aerodynamic noise is caused by the turbulent energy of pressure drop that cannot go into increasing the bulk fluid velocity- which is why pressure drops resulting in sonic velocity are very noisy (the energy must go somewhere). The volume of flow possible in a 24" line increases the noise proportionally. Presumably the vendor sizing the valve understands the application and would not deliberately design something that would fail mechanically even though the application involves a generally undesirable (and in some cases unavoidable) amount of source noise.
just my thoughts, sshep
RE: CONTROL VALVE NOISE
Good luck,
CARF
www.carf-engineering.com
RE: CONTROL VALVE NOISE
Butterfly valve is sensitive to vibration and might get damaged with time if much vibrations present in the valve disk.
Regards
RE: CONTROL VALVE NOISE
with valves, especially butterflf designs, high noise invariably coincides with reduced valve reliability and life time.
noisy HEX are another problem all together
RE: CONTROL VALVE NOISE
Thanks for your observations and for teaching me something. As a mechanical engineer you are probably much better informed about the nature of damage and repairs.
As a chemical engineer my experience has been that there are usually very few economic alternatives to butterfly valves in large vapor lines. We (chem e's) can essentually only deliver up the correct process conditions and require that the vendor either deliver something that works or notify us if he can't.
I believe our butterfly valve mechanical problems (in clean vapor service anyway) are primarily due to movement wear in the shaft, linkages, and actuators rather than damage to the disk or other wetted components such as might occure with cavitation or critical frequency vibration at lower noise levels. Since you obviously have more applicable experience with mechanical problems, I would be interested to learn what types of damage you are observing in your butterfly valves.
Thanks and best wishes, sshep