Vibration Analysis

[tbedford]

I would have thought this would be an easy issue to resolve but I may need a re-focus.

I have commissioned 40 Daikin VRV (variable refrigerant flow) fan coils on two floors with the requisite condensing appliances. The system is working like a charm. There are no vibration issues at this time. However...it is a LEED building and I need to provide some documentation to validate the anti-vibration efforts supplied by mechanical contractor and the manufacturer. The usual...rubber grommets at fan mounts, canvas connectors (supply and return), neoprene pads, etc...

I could simply design a form and sign it saying it met spec(a surprising very light spec)and be done with it.

My curiousity is getting the better of me here and I am asking if anyone is aware of a vibration primer for those of us in the HVAC&R industry.

This project is straightforward, but I have been in machine rooms with 16 of 10HP compressors all on isolating springs, vibrasorbers, etc...and the rooms nearby still have a low frequency hum to them.

I guess that is why some folks dedicate their time to vibration analysis.

Thank for any assistance

Tom

 

[electricpete]

A pretty thorough overview of practical industrial vibration monitoring here:

http://www.update-intl.com/VibrationBook.htm

Needless to say, it would be helpful to determine the vibration of the hum and to take vibration measurements (including spectra) on the machines and possibly bases below them to help see what's going on.

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(2B)+(2B)' ?

 

[Tmoose]

The ASHRAE handbooks are concise and plainly written. Every sentence counts.
IN years past there is an entire section on noise and vibration control.

http://www.ashrae.org/publications/detail/16340

 

[drawoh]

tbedford,

Are you an engineer or a technician? Vibrations are taught in college.

JHG

 

[GregLocock]

These may help

http://www.eng-tips.com/faq.cfm?pid=384

I can't say my university vibrations course was much help in getting to grips with the nitty gritty end of things, useful though it turned out to be.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[electricpete]

From my perspective, there are two completely different types of courses:

1 - University course in vibration which teaches us how to mathematically predict vibration for a given system.
2 – Vibration technician/analyst course (typically not university, but offered by Technical Associates, Entek, CSI, Vib Institute) - teaches practical aspects of diagnosing vibration symptoms in rotating machinery.

Neither one substitutes for the other. You can certainly do more with both than with only one.

The link that I posted corresponds to the 2nd type. It covers information roughly equivalent to a typical 40-hour vibration tech/analyst course. And it's free.


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(2B)+(2B)' ?

 

[tbedford]

Thanks to all,

I am not an engineer...a technical type, refrigeration mechanic by trade.
The reference to earlier posts is most helpful.
I think one of the 5 day courses would be beneficial. Now I have to figure out how to get away for 5 days.

thanks again to all,

Tom