PTS Flowbench Forum

Ok, knowing what plates you have . . .

If you test the 150@16"/198@28 plate and test at 16" of static you should be at 62% on your scale if you test that same plate at 28" you will be at 82% for a cfm of 198@28".

Each of the plates you have should allow you to calibrate around 80-82% of the internal plates range for each range you have. As we discussed I worked out plates that would give you roughly those results. Going below 60% on water gauges is not the preferred testing method

Sorry... I should have said "emphasized" that this test was through a BMW head.

I thought about the testing @28" last night and will try it today or tomorrow. I am pushing the limits of my available power. That is really why I thought to just run 4 motors and test at 16"wc.

Your test here is a good example of that, rather than test at 16" and calculate the flow at 28", it would have been simpler (and probably more accurate) to just run the vertical manometer up to 28" then your inclined manometer would have read 72.8% .728 X240 = 174.7 cfm.

The plate id 317@28"x240@16".

With that said... I will calibrate using the above inside and a 198@28"x150@16" on top.
I will run the U mono up to 28", and with the incline set @ 16" rise. What should I expect the incline to read?

Brucepts wrote: If you test the 150@16"/198@28 plate and test at 16" of static you should be at 62% on your scale if you test that same plate at 28" you will be at 82% for a cfm of 198@28".

Each of the plates you have should allow you to calibrate around 80-82% of the internal plates range for each range you have. As we discussed I worked out plates that would give you roughly those results. Going below 60% on water gauges is not the preferred testing method

What I posted earlier

You can also use the 132@28" plate for a second calibration plate for the 240@16 internal plate this will get you 55%, by using two plates and can get your incline scale linear across a range or as close to linear as you can by changing the tilt/angle of the scale.

You can also use the 132@28" plate for a second calibration plate for the 240@16 internal plate this will get you 55%, by using two plates and can get your incline scale linear across a range or as close to linear as you can by changing the tilt/angle of the scale.

Yup. I meant to reply to that. Had to run out the door. Thanks Bruce. I will try that.

Bruce,

If you test the 150@16"/198@28 plate and test at 16" of static you should be at 62% on your scale if you test that same plate at 28" you will be at 82% for a cfm of 198@28".

Is this plate in or out and which one would be the other?

You can also use the 132@28" plate for a second calibration plate for the 240@16 internal plate this will get you 55%, by using two plates and can get your incline scale linear across a range or as close to linear as you can by changing the tilt/angle of the scale.

I tested the 132@28"... @ 28" and got 53%. Should I adjust my scale 55%?

The calibration plates would be out but you can also test them at 16" and 28" on top of your flowbench to give you a "warm fuzzy feeling" your bench tests the same on 16" and 28"

What did you get with the other plate @28"? Split the difference to give you a nice linear reading, it's really up to you as the user for what you want to see.

That's the nice thing about being homebuilt you can calibrate it to your hearts content or run it as is . . .

Welcome to the world of flowbenching!!

What did you get with the other plate @28"? Split the difference to give you a nice linear reading, it's really up to you as the user for what you want to see.

Am I missing something... but I assume that you need a "restriction" inside (plate) and outside (plate for calibration or object testing)?

You've got to shake the idea that your test pressure is limited by the inclined manometer, that's NOT the case You can run the test pressure up as high as you like as long as the flow through your test piece doesn't exceed the rating of your calibrated orifice at 100%.

I think I understand this part now.

Thanks.

rvaughnp wrote: Am I missing something... but I assume that you need a "restriction" inside (plate) and outside (plate for calibration or object testing)?

You have the 240@16" plate inside your flowbench, think we established this a few posts back correct?

I would suggest you lose the % scale on the incline and go to a metric scale in MM use Rocco's spreadsheet and do the following.

Put the 240 CFM @ 16 Plate inside the bench, Put the 132CFM @ 28 plate on top of the bech. Pull the bench to 28" on your virtical monometer then read the incline in MM's.

DO THE MATH in Roccos sheet. see what it says if the flow number is high, increase the angle of the incline and re-zero. test again. if to low decrease the angel re-zero test again. you will then get calibrated and can flow any head you like.

Until you understand the math behind the flow numbers you are just chasing your tail playing with the % scale.

Besides it is alot easier to just plug the incline # into the spreadsheet that does the math then right some crap down and calculate 62.5% of a 240CMF plate.

Rick

PS. BTW what makes an inlarged photo copy of % scale accurate in any way?
Dont get me wrong but this % scale is somthing SF came up with thinking it made things easier (before computers)