Noise Mitigation around Piping

[SnazyDragon]

I am currently working on a design for some noise mitigation which involves piping that requires new acoustic lagging. Some of the piping has existing acoustic lagging. The bare piping where new lagging is required will also require an attenuation. What is the best practice or option for determining insulation lagging specifications if I am not able to determine the frequency of these various sound sources?

 

[Tmoose]

Does the existing lagging perform satisfactorily ? That /// MigHt /// be a start.

Sometimes piping noise is a result of inadequate or improper mounting, with the result there is transmitted vibration that gleefully uses every available interior surface as a loudspeaker. Lagging can't help that.

Have you been to the site to hear the situation?
Perhaps a colleague or a site contact can record some videos with sound that can clarify the problem.
Designing "blind" ( actually deaf, I guess) is a recipe well calculated for di$a$ter.

Got some history, like, the noise complaints started when we installed some nice new VFDs to drive the pumps, etc, etc.

 

[hydtools]

Go listen. The ear is a very good frequency analyzer.

Ted

 

[Strong]

"What is the best practice or option for determining insulation lagging specifications if I am not able to determine the frequency of these various sound sources?"

If you can't quantify what attenuation is needed by actual sound measurements, then all you can reasonably specify is the same "acoustic" insulation that was installed. Note that some "acoustic" insulation is really thermal lagging with extra marketing and not extra engineering!

"The ear is a very good frequency analyzer" Not true unless the ear is well calibrated against sound measurements, including ear frequency response testing! Sound meters and FFT analyzers/software is low in cost, and can provide useful data, even by a neophyte.

Walt

 

[racookpe1978]

Is the "pipe" releasing the noise, or is the pipe's "insulation, pipe supportts, mounted equipment, valves and valve actuators, pipe support structural steel, etc. " releasing the noise?

What is noisy on one pipe support may not be noisy at a 2nd, 3rd, or 4th, but noisy again at the 5th pipe support. One elbow or control valve may be noisy, and the next quiet enough. You MUST map the AREA sound levels to fight EACH noise spot in turn. A single blanket solution (lead-filled blankets on the pipe itself, for example) while excellent in theory, may be useless for 8 of your 10 noisiest spots. But work perfectly and cheaply for those 2 places!

 

[chicopee]

The question I am asking to the OP is what's causing the noise? then perhaps a proper answer will be set forth.

 

[SnazyDragon]

Hello All,

I've identified the sources of the sound and have had some measurements done on the piping to determine the attenuation of sound levels required for frequencies ranging from 125-8k hertz. Looking at options of lagging and insulation, it appears that these solutions will only effectively attenuate high frequency noise. What are my options for the low frequency noise control? Has anyone dealt with this before?

 

[12345abc6ttyui67]

I've identified the sources of the sound

Care to enlighten us?

 

[SnazyDragon]

gaseous flow thru piping is causing noise. does not appear to be caused by supports or vibrating connections to the piping.

 

[hydtools]

Cover pipe with lead-vinyl blankets. A heavy barrier material.

Ted

 

[Tmoose]

Just to confirm, "some of the piping has existing acoustic lagging." And the performance of the old lagging is judged unacceptable, and THAT is why it is being replaced, along with new lagging on some new piping.

 

[SnazyDragon]

This is correct @Tmoose

 

[chicopee]

So you have some type of liquid with some type of gas or (vapor?) entrained in the liquid. Is that so?