Lost...SF110 style bench build

[ThomasVaught]

Some like Super Flow used a Square Edged orifice plate so that the bench could read in both directions. The calculations on the spreadsheet on the forum assumes a sharp edged orifice around .62 but you could recalibrate and determine the flows with a square orifice plate by testing.

The plates from Bruce could be flipped for intake vs exhaust like Bruce does in his flow bench plans. Several solutions including the one you proposed. I personally am not a big fan of the "pipe" methods as you need many diameters of length to make it work properly.

Tom V.

[gofaster]

If you use sharp edged orifices instead of square edged, you'll need to be able to turn them over for exhaust testing. Also, the SF110 uses 4 motors, 2 for intake and two for exhaust. You may not be able to pull enough air with one motor to duplicate the results of a "110"

[WPH]

Took me a while to repair and modify my bench after blowing
a motor gasket. The new setup:

top plate orificies 50.5, 37.8, 31.4, 25.2 and 18.8mm, square edge. Flow @ 3"
DP, .58 Cd (calculated) 86, 48, 34, 21 and 12 cfm. Material 1/16" steel

Calibration plates sharp edge, 14 deg undercut. Diameters 25.40, 31.80, 38.10, 47.65 and 50.8mm.

I took some numbers down when I was testing my new stuff:

- pulls about 12" of vacuum with my 47.65mm calibration plate
- measured 27mm of DP rise over holes 1,2,3,4 and 5 open @10"
- 88 mm of rise with 1,2,3 and 4 open @10"
- 151mm of rise over hole #5
- 80mm of rise over #5+3

- tested 50.8mm orifice 1+2+3+4 and 5 @10", got 35mm. 90mm of rise over holes 1+2+3+4, this was @ 8" of test pressure.
Can't pull 10" if hole #5 is closed. I have to run these tests again, seems a bit odd (not being able to pull 10" with #5 closed)

Do these numbers make any sense? My DP over top plate seems a bit low?

More pictures (orifice plates) at previous link. (Edit)

[larrycavan]

[ThomasVaught]

Make sure that you don't have one of the orifice holes impacting on the Delta P pick-up.

Tom V.

[WPH]

This is correct. 10" with 50.8 plate was the first pull and and my motors might have been under their steady operating temperature.
I'm only 1/2" below 10" with #5 closed. These DP numbers were measured with a small vertical manometer so they are not very accurate.
DeltaP-pickup is in the top left corner of bench, closest to the 50.5 orifice. It might be an issue, I'll try to replace it.

Does 3" rise over run look ok for my inclined? I have one more installation hole for another motor but that is very close to my
electrical connection limit and I'd prefer not to install it if readings are ok.

(Edit)

Test results with 50.8mm are verified. No 10" with orifice #5 closed. All open results 10".Flow direction in top chamber affects DP by
3mm (horizontal flow gains 3mm over vertical. See my pictures, 3" additional flowpath for testing purposes).
Changing DeltaP-pickup to opposite corner looses 1-2mm. Looks like I'm going to need one more motor to go... or maybe my 60mm flow control valves are too small.

[ThomasVaught]

You want the Test part and the orifices to be the controlling factors in
your bench, not the control valves. I would look into either duplicate valves with a cross link or a larger valve.

Tom V.

[WPH]

I ran my test with ball valve open and closed. 3mm DP gain on horizontal flow was due kinetic/dynamic pressure.
Ball valve + additional path open resulted lower numbers. I will block my 3" path and verify results.

All orificies open I should be in 200CFM range if my math is correct. With 3" DP I should be seeing 3/4 = 58mm
with 47.65mm orifice but I'm getting less than half (=27-28mm).
I think that my blowers just don't produce enough CFM to create sufficient DP over top orificies

[WPH]

I'm at my wit's end with my bench. Added one more motor, it pulls 16" of vacuum through my 2" calibration plate
but DP over measuring orificies @200 CFM calculated range(3" DP) does not look like what it should be. I'm getting
only 38-40mm (1.496"-1.575") and my previous problem was replicated again (unable to pull 16" if enough measuring orificies are blocked).
I was thinking of an internal leak but I did a test pull with both flow controllers closed and could not measure any flow.

My intake and exhaust flowcontrol (depression) valves are 60mm in diameter. Do you think that they might be too small,
I guesstimated that they might flow 190-200CFM at 10" with Cd = 0.50. Valve body is 20mm long and it has 45 deg 4mm wide seat angle.

[WPH]

It took a while, but it was really worth it. I re-designed my whole measuring combination and got some nice results.

These are my numbers:

Plate # 1 (calculated flow @ 10" WC 94.4 CFM, Cd 0.61)
Plate # 2 (calculated flow @ 10" WC 148.5 CFM, Cd 0.61)
Plate # 3 (calculated flow @ 10" WC 168.7 CFM, Cd 0.61)

Measured leak 2.6 CFM

#1 measured 93.7 cfm

#2 measured 143.7, 144.2 and 145 cfm, 3 different range combinations used

#3 measured 165.6 cfm


I made 500mm long, 6" rise over run manometer. I found a spreadsheet for 1meter "yardstick" manometer and converteted
it to 500mm. This gives me flow% directly from my mm scale, and I use ONLY 2 orificies at the same time.
I used 0.60 Cd for my measuring orificies and that seems to be quite close. Things left to do is to flow my plates (SF110+FlowCom)
at the 1st week of March and get my final calibration sorted out. I will post the results as soon as I get them.

Thanks to everybody at this forum, couldn't have done it without your help.