Inlet & Exhaust sizing - How big an area is needed

[1960flh]

I am in my final design phase and am trying to get an idea of how much area i need for my fresh air intake and exhaust. Since these will be using 3" or 4" pvc i was not sure how many of each i would need. My plan currently is to use 16 of the Suplus center motors. I want to use gate valves so i can have 1 lever to switch test modes from intake to exhaust.

Any thoughts?

Thanks

Rick

[gofaster]

I used the spreadsheet to figure out my openings, by inputting the info I knew, test pressure, expected max cfm, etc. If you go to the spreadsheet section and download the excel spreadsheet, it is very easy to use, and self expanatory. Be sure NOT to change any values that are not supposed to be messed with.



Edited By gofaster on 1172629469

[1960flh]

Jim;

I might not have been clear here but what i am trying to get a grasp on is for my fresh air intake and/or exhaust. Many people are using plates or the Beckson hatches but i would like to incorporate the sitching of modes (Intake testing or Exhaust testing) with the opening or closing of the fresh air ports without creating much of a restriction. My thoughts are that 2, 4 inch PVC pipes should provide enough flow of fresh air in or exhaust out but i am not sure. I did not see a sheet that adressed this issue.

Hope that clears up the question.

Thanks

Rick

[2seater]

You could calculate the restriction based on flow through a tube or an orifice, but there will be some restriction no matter how large the opening(s). If everything scaled up to double the motors and output of the setup I use, that will be around 1000 cfm @ 28", a very large amount of air flow. Restriction will increase as the flow goes up. It may not be enough to bother you, you have a lot of power on tap. I will try an empirical test on my motor box and see what sort of pressure is generated in the box with the six motors running and the single 4" outlet disconnected from the bench.

[2seater]

I went out and tried my test. My motor box is seperate from the bench, and it may have some built in restriction due to the shape. My test was with the 4" toilet flange open to atmosphere and I am configured in the blow mode right now. The inlet side of the box is open to atmosphere completely (motors exposed). I have a small bleeder valve connected to the box for fine adjustment and I used that to read the pressure connected to one of my inclined manomenters. The end of the tube from my inclined was covered with a couple of layers of cloth to minimize any impact velocity affecting the reading. In any case, with six motors running, it showed 3.1" of H2O pressure in the box with the 4" flange wide open. Hope that helps

Oops, I noticed you have (16) motors. I think you will need a very large opening(s) or it will have a noticeable effect at really high flows.

[gofaster]

Rick,
I thought the information was in the spreadsheet section, but I guess I'm mistaken. Now I think it was on the program that Larry Cavan sent me.
I used Larry's program to figure out what size to make the flow control valves, and the orifices in my plate, and to make sure the deckplates would be adequate for the feed and discharge openings for the vac motors. I think that's what you're trying to determine?
It's not on this computer, so it's probably at the shop.

[1960flh]

Thanks 2 seater thats the kid of data i am looking for, stil not sure but headed in the right direction.

Jim, i have a couple of Larry's sheets i will look them over for more information.

Rick