Holes in spiral duct for air distribution 1

[TWzero]

I have a client who is insisting on using spiral pipe with holes for specific air distribution over certain areas. It has been a long time since I've dealt with the calculations to be honest, and cant seem to find my reference material. Can anyone one point me in the right direction as to how to size holes, and the static pressure for the holes.?

 

[MintJulep]

http://www.mcgillairflow.com/textDocs/ddFuser/dd_typeSP.htm

 

[TWzero]

I would rather calculate based on what the end user is requesting, than buy a product, as we can fabricate the spiral in house. Thanks though

 

[cry22]

You are asking for R&D material. If you have to fabricate, you will need to make prototypes and test for airflow and pressure drop.
Or try to reverse engineer a manufactured product.

The link from MintJulip is what any HVAC engineer here will likely direct you to.

 

[marcoh]

Have a look at

http://www.flaktwoods.com

They make round duct with nozzles which may be what you are after.

Alternatively fabric ducts often have holes in the ductwork, which would be a starting point.

 

[Target50]

Hi Guys here is what we use for holes in spiral and I can say it works great. Tried tested and true.

 

[ChrisConley]

For a long run, I'd recommend making the first 1/3 holes a little smaller, and the rest a little larger. Not significant variation in hole diameter, just a little 'built-in' balancing.

 

[AbbyNormal]

Ground control to Chris Conley

Take the "V" out of HVAC and you are left with a HAC(k) job.

 

[ChrisConley]

Funny, I'd forgotten that I posted in this thread. I've got a great memory, just short. Thanks Abby....

 

[BronYrAur]

Target50, I don't see where the 1.514 in your calculation comes from. Shouldn't you be using the surface area of a 1" diameter opening (0.7844 sqin)?