PTS plate CD

[ftch]

Not an accurate test yet however i had the bench at my28 inches. And a test piece mounted.
I HAD the pts 3.490 diameter 660 at 16 inch flow plate in.
I measured the pressure differential of 10.5 inches using a vertical manometer across the plate.

Can anyone help with this math.

I going to fit digital setup shortly however this is helping me understand it all better.

Thanks again
Michael Marriott
Australia

[86rocco]

If you're using my spreadsheet, just enter the orifice diameter, the differential pressure you measured and a CD of 0.62 and it gives you an answer of 534.7 so, your test piece flow 534.7 cfm @ 28"

flowcalc.JPG

If you want to do the calculation manually, you use the orifice's rated values of the 660 cfm at 16"WC as follows: divide your measured pressure differential of 10.5 by 16.0, take the square root of the result and multiply that number by 660.

flowcalc2.JPG

FWIW, I always recommend that people do the calculations manually when they're first starting out, it helps build an understanding of the underlying mathematics which will serve you well if you ever run into problems or if you want to do anything outside the norm.

[ftch]

Thanks so much for your sheet 86rocco its really awesome and I know a lot of people appericate it.

Now I understand how the bench works much better .

I also think if im correct, if I want to I can use an incline manometer now. if I happen to use a 10.5 " incline manometer
10.5 = 100% = 534.7

I want the abilty to be able to use both manual and digital manometers

Because this bench can pull a high differental pressure what would be consider the best incline manometer range.
The earlier small benches only had 2" The bigger Standard superflow 246 manometer is 6". I belive the accuracy goes up as the DP rises. I know the PTS electronic uses a maximum of 16"
There also must be a balance at the cylinder head end if im correct a small DP at the orrifice plate allows for a higher test pressure if im correct.

Really appericate this forum so much
Michael Marriott
Australia

[86rocco]

In your case, what I think I might do is install the largest orifice you have in the bench, put some sort of adjustable test piece on the bench, turn on all the motors on maximum, adjust the test piece so you've get 28" depression and measure the pressure difference across the orifice and use that value or 16" (which ever is lower) for 100% on your incline manometer.

[ftch]

thanks again 86rocco.

I am interested in what is to low a DP across the plates , for my own interest. I have read the higher DP the more accurate and repatable. The dwyer 246 which is what superflow used must be working best in the 4' to 6 " range, and is this enough?

If there is a good thread on this subject I would appericate that.

My current biggest plate is 660 3.490. I think it could easly pull somewhere around 12" DP across the plate at 28"

apperciate your interest.

kind regards
Michael Marriott
Australia