Re: Free air calculation.
Best/easiest way is to make up a cardboard air collection hood, calibrate it and then take all of your readings with the hood.
edit: Just checked with Lindab catalogue, they don't give free areas (damn). Looks like you'll have to measure the slots yourself. ;)
Re: Free air calculation.
Hello
If the air distribution system incorporates a moderate number of air terminals, I would recommend hiring a propriety 'flow measuring hood' for the job. These instruments employ balometer technology to measure the volume flow rate and normally include digital displays with high resolution. It is important to examine the calibration certificate before you leave the store to verify the instruments accuracy. It can be very difficult to attain accurate and consistant readings without the appropriate equipment.
Depending on the quantity of terminals to be measured, alot of time can be saved if you have an assistant to identify the terminal and record the respective flow rates while comparing against design figures.
Hope this helps.
Solas
Re: Free air calculation.
46% according to the downloads here
ooooooPs, I've always used 60% in my calcs :o, my systems always work though.
Eggs
Re: Free air calculation.
Re: Free air calculation.
use an anomometer and a tape measure.
Lineal metres flow x metres squared is total flow.
Lots of lineal flow readings and average. Not rocket science stuff.
magoo
Re: Free air calculation.
Quote:
Originally Posted by
Magoo
Not rocket science stuff.
magoo
Neither is reading the question. :(
Quote:
Originally Posted by
coolhandlew
Does anyone know roughly the free air area of a 600x600 4 way supply diffuser?
Eggs
Re: Free air calculation.
Quote:
Originally Posted by
Magoo
use an anomometer and a tape measure.
Lineal metres flow x metres squared is total flow.
Lots of lineal flow readings and average. Not rocket science stuff.
magoo
I'm well aware of that, but there has to be a correction factor for restrictions ie. louvres etc
Re: Free air calculation.
For "eggs "and everyone else there is a standard for a difuser hood testing forget about louvers .., what ever comes out is actual, my initial comment stands.
For commissioning a/c diffusers a square test hood that reduces from square to round with a fixed discharge diameter, add anemometer will give the actual flow rates, the angle from square to round to meet standard is 11 degrees. Then use calcultor and flow rates. Like I said earlier not rocket science. The more cross reference readings the better, increases the accurracy.