Outside air

[inspectormechancial]

As a Mechancial Inspector, How can I measure outside air complaince? Is their a table I can use? Example: Plans call for 350 cfm of OA. How can I field verify?

 

[IRstuff]

Seems to me that a measurement of air velocity at the OA intake duct would be more appropriate than consulting a "table" that might have little bearing on the actual design or implementation.

TTFN

FAQ731-376

 

[inspectormechancial]

Thanks,
but as an inspector we(I) don't have any means of measuring air flows. I guess the only way to verify complaince is obtaining an air balance report? Many of our small tenant contractors or owners doing their own work find the cost of this service out of their work and don't figure this cost in. It is a code requirement, and we cannot final out their jobs until the OA is varified/balance report provide showing the OA has been set to X amount of cfm. I was hoping to find a way an inspector could field verify.

 

[IRstuff]

I guess I don't understand what you mean by "verify."

To me, verification means proving that building code is met or even that the design works as intended. How can you "verify" without some proof that the system is even operational?

You can certainly demonstrate on paper that ducting and fans are present and are capable of meeting the requirement, but how would you know that the builder didn't accidentally wall off the duct or the fan?

TTFN

FAQ731-376

 

[dcasto]

A hand held areonometer will measure the velocity of the air in the duct or whatever, times the area givess Ft^3/min.

If you have a fan moving the air, a reading of the amps pulled by the motor should correlate toa table produced by the fan manufacturere (may need a water tube differential pressure measurement across the fan too).

 

[Warpspeed]

Measure outside air compliance?

That requires an actual measurement.

And as dcasto has already pointed out, to measure something you require a suitable measuring instrument.

A hand held anemometer that can read in feet per minute, is the standard instrument used in the HVAC industry. A measuring tape will get you the flow area in square feet, and a simple division will convert to the CFM of flow.