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Posted:
Thu Jan 10, 2008 3:17 pmby CraigAPD
Hi all,
Ive got a 2" AudiTech FlowQuik unit for which im currently building a testbench. Im basing it on the plans they provide for the plenum and supply box.
My question is, should I be using 2" or 3" pvc tube for the pipework?
I guess either will work, though the plans say 3", but i dont see the point in using 3" when youve got a foot or so of 2" for the pitot tube.
What would (or have) you lot done for similar set-ups?
Cheers!
Craig
Posted:
Thu Jan 10, 2008 3:38 pmby martyester
From talking to Auditech on this subject, it depends on how much flow you want out of your bench. The smaller is for up to (i beleive) 400 CFM and the three inch is for greater flow than 400 CFM. The 2" is more accurate at low CFM readings and for greater than 400 CFM the 2' is two restrictive.
Posted:
Thu Jan 10, 2008 4:13 pmby 106-1194218389
I have a FlowQuik from Audie and the 2" unit is good for up 320 - 330 cfm. He offers a dual tube unit where you can swap a 2" and a 3" tube and the unit itself is calibrated for that - The single tube unit is just calibrated for CFM or the metric equivalent depending on what the user wants to use by setting the knob. My particular FlowQuik unit is actually designed to use either one 2" tube or two 2" tubes in parallel. So when I have one tube it is suppose to work to about 320 to 330 cfm and when both tube are on it should do almost 600 cfm. You can check it out on his web site.
Posted:
Thu Jan 10, 2008 5:51 pmby CraigAPD
But are you using 2" or 3" for the rest of the system?
As said, Ive GOT the 2" unit from them....the plans suggest 3" tube, but the plans are for BOTH the 2" AND 3" units from them. So will I be ok using 2" tubing from the supply etc? Otherwise its going to be 3" reducing to 2" for the test tube, then back to 3".
Posted:
Thu Jan 10, 2008 9:07 pmby 2seater
Either will work but there is much less friction loss with the larger piping, no matter the size of the flow unit, especially if there are any elbows involved. I use conventional pitot flow tubes using Bruce's averaging probes, from 1" id up through 3"id, but all of the rest of the system is 3" or 4". Your vacuum motors will thank you 
Posted:
Thu Jan 10, 2008 9:56 pmby 106-1194218389
I have the two tubes "y'd" to four inch for the rest of the system and when I am using the two tubes I pull from 2 shop vacuums
Posted:
Fri Jan 11, 2008 6:47 amby CraigAPD
Yeah I was thinking last night it will be alot nicer on the motors with 3"....3" it is!
should have it running by next week....i'll post some pics up when she's done