Lost...SF110 style bench build

[WPH]

[color=#000000]This is my first flowbench build which has been on hold for a while. Basically it is a copy of SF 110
but in a larger cabinet. Here are some basic numbers of my project:

60 mm = 2.362

[bruce]

First off nice little flowbench!

I did some math on your orifices at 10" and the Cd is around .30, they appear to be linear when I ran all your diameters they almost matched your cfm results!

So to me your orifices are your restrictions, you need to get their Cd's up to .62 and you'll have a nice repeatable flowbench. Make your orifices out of thin plate, sharp edge is best but a square edge will work also but might not be as linear on the Cd over the full range.

[ThomasVaught]

Bruce, first off some additional info about the SF-110 type bench:

1) It used a 3" delta P inclined manometer

2) The 10" number is the test pressure typically across the test part.

I also checked the numbers using the spread sheet.
I used a 1.86 orifice" I have the real numbers somewhere) for
his 2" hole and set the depression across orifice plate at 3" WC
I can up with a number of about 80 cfm using a .62 cd.

I think his issue is with his pipe orifices as the SF 110 bench used a flat plate that was exposed on the top of the bench as the measurement orifice plate. The bench is a motor centered bench which affects Intake and exhaust readings too.

Flow schematic for intake is Test part, then motors, then orifice plate then atmosphere.

Flow schematic for exhaust is orifice plate, then motors, then test part, then atmosphere.

cd for most sf benches is around .58X

Bruce, Did you assume a 3" delta P across the orifice?

WPH, what is the length and height of your inclined manometer?


Tom V.

[bruce]

Tom, Ran 10" across the orifice

[86rocco1]

What inclined manometer does the SF110 use? I've looked at a few pictures of it and it looks like it might be a Dwyer 209 which has a 3" WC range, that's at least consistant with what Tom said. So, assuming that's correct and using a discharge coefficient of 0.58, I generated flow numbers using the spreadsheet from , here's what I got 88,49,34,22,12.

BTW, I don't know what the discharge coefficient on a Dell carb venturi is but even under the most optimistic estimate, it won't flow any where close to 125 cfm at a 10" DP.

[WPH]

Inclined has a drop of 185mm at 500mm length (measured along the inclined) if thats the correct way to measure it.

I got these measures over the phone years back when I started building my bench.
The scale is as follows: 50%=141mm, 65%=217mm, 75%=274mm, 90%=392mm (few examples)

If I haven't done any mistakes or misunderstood something the scale should be OK, since the calibration of the other bench
was spot on with SF110 under same conditions and correction factors.
I used same kind of orificies and the biggest difference between our benches is blower, he uses a single 3phase.

Oh, I noticed a mistake on my previous post. My test orifice flow was 119,7 CFM on a test bench.

[86rocco1]

Have a look at the spreadsheet I referenced in my previous post, it'll do the inclined manometer calculations for you (sorry it's in inches), to use it, you need to input 5 bits of info, vertical height (185mm), scale length (500mm), tube diameter, well diameter and specific gravity of fluid (1.0 for water). That'll also tell you what the differential pressure at 100% actually is, that'll be useful when calibrating your orifices.

Also, you need to find out what the exact test conditions were for your test orifice that resulted in 119.7 cfm because that number's just not consistent with a 30mm venturi tested at 10".

[86rocco1]

While we're sort of on the topic of the Superflow SF-110 bench, do you (or anyone else) have the equations for the temperature compensations. Is it merely proportional to the change in air density due to temperature increase between the incoming and outgoing air or is there something else involved? I'm asking because I'd like to make a spreadsheet to do that calculation and offer it up to the forum.

[ThomasVaught]

Quote:

"Inclined has a drop of 185mm at 500mm length (measured along the inclined) if thats the correct way to measure it."

Not saying that your "homemade" inclined manometer is not 185mm and 500mm length.
Saying that the factory SF110 inclined manometer does not have the same "rise over run" that your set-up does. If you look at this picture of a 110-120 type bench:



and then look at the vertical manometer in the pic and compare it with the inclined manometer well you can see that it is approximately a 3" DP
unit.

Tom V.

ps Quote:

"While we're sort of on the topic of the Superflow SF-110 bench, do you (or anyone else) have the equations for the temperature compensations. Is it merely proportional to the change in air density due to temperature increase between the incoming and outgoing air or is there something else involved? I'm asking because I'd like to make a spreadsheet to do that calculation and offer it up to the forum."

I have that temp correction somewhere on my work computer if someone with a SF-110-120 bench can't offer it up.

From the SF Website:

"The exception to this is on the SF-60 and the SF-110/120 flowbenches. They both have the blower actually located in-between the inlet orifice and the outlet orifice, because that makes for a less expensive design. A temperature correction, which ranges from 0 to 4%, is necessary. There are thermometers built into these flowbenches for this correction."

[WPH]

Here is the chart

[86rocco1]

[color=#000000]Thanks, I'll see if I can figure out how those number were generated, it looks like just under .004 for every 5

[ThomasVaught]

Numbers are in degrees F

Tom V.

[WPH]

Did I get this right: factory (SF) uses 3"WC DP to measure flow through orificies 1,2,3,4 and 5.
That's what I should use on my manometer scale (vertical height) ? I will be using water as my fluid so how does
this influence on my manometer design and calibration ?

What is the max thickness for orificeplate? I have access to CNC sheetmetal cuttingcenter to get it done.

[ThomasVaught]

Quote:

"Did I get this right: factory (SF) uses 3"WC DP to measure flow through orificies 1,2,3,4 and 5."

Correct! SF does not use a 6" H2O orifice depression calibration like they use on the SF300, Sf-600, and SF1200 benches. The SF300 and SF1200 use red .826 sg fluid in a Dwyer 246 Manometer. The SF600 uses approximately 1.91 sg fluid with the same Dwyer 246 6" manometer to get the approximate 50% larger range per orifice. A SF300 has ranges of 25 cfm, 50, cfm, 100 cfm, 200 cfm, 300 cfm and 400 cfm. A SF600 has ranges of 25 * 1.5 = 37 cfm, 50 * 1.5 = 75 cfm, 100 * 1.5 = 150 cfm, 200 * 1.5 = 350 cfm, 300 * 1.5 = 450 cfm and 400 * 1.5 = 600 cfm..... They both used the same sized orifices! Make sense?

Quote:

"That's what I should use on my manometer scale (vertical height) ? I will be using water as my fluid so how does this influence on my manometer design and calibration ?"

Either make a custom top orifice plate using the forum spreadsheet to calculate the numbers, revise your homemade inclinded manometer to read 3" DP, or buy a Dwyer 209 inclined manometer that will read the correct depression.

Quote:

"What is the max thickness for orificeplate? I have access to CNC sheetmetal cutting center to get it done."

I have made very accurate orifice plates in the past using .125" (1/8") mild steel material. I put a 45 degree back cut on one side. The edge was a sharp edge where the airflow entered the orifice. Maybe Bruce could make you some orifice plates and you could attach these plates to the top of your bench and epoxy seal the butted sections.

Tom V.

[49-1183904562]

Tom;

Would it not be better to to use somthing like 1/16 stainless with a square edge (lower CD than the Pipe he is usnig) since this plate will be flowing in both directions and also be subject to some type of rubber stoper (edge deformation).

Jst a thought

Rick

Happy new year to you all!