Connecting impellers to systems

[BobL]

I've had the mobile phone version of the latest version of the Loren Cook Engineers cookbook for a while and was slowly reading through it when I had a spare moment on two.

Today I can across an interesting comparison of "smooth bore bends with segmented bends" and have posted about this here.
http://www.woodworkforums.com/f200/ducting-update-205361/5#post2022379

The next useful thing I came across what standards for connecting impellers to ducting on both the inlet and outlet side and it provides some very clear diagrams of what not to do and how to do it better. It shows that elbows located too close to inlets and outlets should be avoided.

411958
411959

The cook book has lots of stuff it in and is definitely worth a quick browse.

Oh yeah, and the link to the cook book is http://www.lorencook.com/PDFs/Catalogs/Cookbook_2016.pdf

[mannum3]

Thank's Bob,

How does this compare with the outlet from the blower at the Men's Shed?

We will have to modify ours at Mannum.

Cheers Barry ps downloaded the cookbook:)

[BobL]

The inlet to the impeller is inside the cyclone so the diagrams don't apply to the impeller inlet. However it does apply to some extent to the cyclone inlet. So having 2.5 duct diameters (500 mm) of straight ducting between the cyclone and any junction is worth considering. The CV comes with a round to rectangular connection which nearly meets that condition but adding a bit extra straight ducting will help. At the mens shed we have used a straight 8" to 9" diameter reducer because our "elbow" or connection to the shed is a piece of 9" flexy with a large radius of curvature.

The outlet on a CV max impeller is very short and is normally directly attached to a 1R radius of curvature elbow that leads to a filter/muffler.
This is not ideal and neither is the 1R elbow but this is done by CV to reduce the foot print of their system.

At the mens shed we have not used the 1R elbow but made up and used a 2.5R rectangular elbow.
Based on my experiments on air flows through elbows I'm really glad I pushed that
Ideally there would be a short straight length of 2.5 x duct diameter (i.e. 2.5X 200 = 500 mm) length of ducting between the impeller and any elbow but that further increases the footprint so we have forgone that.

[mannum3]

Mannum had the help of WA's top sheet metal man (MetalTorque) who was visiting a member here, "Blue", they spent an evening on the kitchen floor drafting out the plans on butchers paper for the cyclone, they made the inlet transition from rectangle to round about a metre long. a great job.

The outlet was made by a enthusiastic chap without directions, a very short and sharp bend.

We can make the next one to your specifications, thanks Bob.

Cheers Barry:)