PTS Flowbench Forum

jfholm wrote:Now if I understand it correctly you are trying to check the 3.5" orifice on top of the bench at 28" correct? The 3.059" one is inside and that one gets it's value from the Delta P of 13.4" H2O.

I was just thinking that if I had a larger hole on top of the bench and put the manometer at 28" whatever it pulled through the 3.059 hole would be the true factor for that hole.

However, if the 13.4 is the true delta, what should the factor be? Not 442.2??

Chad Speier wrote:Yes I had the FP in manometer mode.

If they are indeed calibrating at 13" then the 442.2 is not correct?? And if it should be 449.5 instead of 442.2 then my 356 plate at 78.2% would really be 352 cfm.

correct??

Yes, What I would like to do some time is put a head on my bench and check the Delta P at 25%, 50%, 75% and 100% manometer reading and check the Delta P at each reading. If you are testing at 28" that will be the reading above the orifice and the reading below the orifice on the vacuum source side of the orifice should be 41.4" H2O if you are getting a 13.4" H2O delta P. I would think that would stay steady.

The value of your internal orifice stays the same in relationship to your delta P

John

So, if it's truly a 449.5 correction, I'm now within 3-5 cfm on all my plates compared to my old bench and the SF with the FP.

I have several SF sheets from various customers and nothing this low. Several 449.xx!!!!!!!!!!!!!!!!!!!

Does all this sound logical?

78.2% = 351.5 cfm
97.4% = 437.8 cfm

How do you arrive at 449.5 from 13.4 delta?

I have been going off of the program Ed put on the forum to help calculate the flow through an orifice. I will attach it so you do not have to hunt for it. Thanks Ed! Great program. It uses Microsoft excel

John

Chad Speier wrote:So, if it's truly a 449.5 correction, I'm now within 3-5 cfm on all my plates compared to my old bench and the SF with the FP.

I have several SF sheets from various customers and nothing this low. Several 449.xx!!!!!!!!!!!!!!!!!!!

Does all this sound logical?

78.2% = 351.5 cfm
97.4% = 437.8 cfm

How do you arrive at 449.5 from 13.4 delta?

That is the way I figured it

John

Chad,

What Delta P did you set for the FP1 to use for CFM Calculations?

Rick

Keep in mind the FP1 uses a 40" sensor on channel 2 and the PTS DM uses a 16" sensor on channel 2

You are working in different ranges of the sensor on each DM. It does not appear to be effecting those readings but wanted to point that out.

1960FL wrote:Chad,

What Delta P did you set for the FP1 to use for CFM Calculations?

Rick

I had the FP at .600, is this what your asking??

Here is what I did. Put the FP in manometer mode.

Calibrated the 1.770 hole and it has a .60 dc. I put a head on the bench and read the FP for delta.

ALL readings at 28" on manometer and FP

25% NO WAY! not enough patience to find it correctly
50% 3.35
75% 7.62
100% 13.40

Calibrated the 3.059 hole and it also has a .60 dc

25% .81
50% 3.34
75% 7.63
100% 13.35

Chad,

I know you are probably getting tired of my off the wall posts but I am trying to understand what SF’s intentions were in there design so we have a logical path to follow to a comparative calibration.

First off the Intended (Design) Delta P is most likely 13.37 not 13.4 yes splitting hairs but it equated to .5 CFM. To my earlier point I do not believe anyone makes a 7.015” rise manometer, thus we know you measured it at around 13.4. So the SG of the oil used is 1.91 the rise of the incline must be 7” and thus DP = 7” * 1.91 or 13.37” based on the SF documentation #5 range is 0 to 450 cfm by using the spreadsheet with air density standards a Preasure of 13.37 and orifice ID of 3.059 then to get to 450.0 the CD they designed around will be .6014.

Am I understanding your posts correctly? But again I am not sure where you are getting the 442.2 /442.9 Number you are using in your flow calc? it is my understanding that #5 on the SF 600 is 0 to 450CFM.