Calibration Help - Having problems

[86rocco1]

Jake, A lot of that math is basically that same as what's in my spreadsheet, some of the numbers used are different because they're talking about water flow and because they're expressing their results in gallons per minute rather then cubic feet per minute.

I'll look over it and see if I can bring it down to a level that most people here can understand.

[jakesportingservice]

Thanks Ed your spread sheet is great and it is helping alot to figure out what is going on i think it will get figured out just might take a little time to do so .

Thanks Jake

[jakesportingservice]

Ok i have some data to post i made 5 plates tonite and tested them on the bench and here is what i've come up with all tests are completed at 28" water on the vertical.

1.280 orifice 24% on inclined 117.84 cfm
1.525 orifice 33.5% on inclined 164.48 cfm
1.750 orifice 43% on inclined 211.13 cfm
1.980 orifice 54.75% on inclined 268.82 cfm
2.560 orifice 93.5% on inclined 459.08 cfm


I've used a number of 491 to calculate these values as i put the numbers in the spread sheet with the inches of wc from the spread sheet for the inclined with a orifice diameter of 3.06 which is range five on my rotating disk. I think i have it figured that a .665 is the average cd and all of my numbers seem to correspond to that.
Let me know if you think i'm on the right track or if not I guess i will need more assitance.

Thanks for all the help Jake

[jfholm]

Jake,
One thing you will find is you need to be flowing the orifice above 40% on your inclined for it to be accurate. That is the reason you need so many orifices. With the digital you don't seem to have this issue, but I know that with the fluid manometers the accuracy is marginal below the 40% reading.
John

[bruce]

I'm getting a Cd of .60 avg for my math? Using a 3.058 diameter plate (my math your plate is 3.06) with a Dp of 13.5 (vertical rise of the incline) you would have 466 cfm at 100% on plate 5.

[jfholm]

I used Ed's spreadsheet and came up with a Dp of 13.03" because the specific gravity is .876 due to MMO - I set the CD to .62 which is what I figured my square edged orifices came out to be. Anyway, I have to verify with Bruce that the 100% cfm for that orifice should be 466 cfm.

But, if it is acting like an orifice in a pipe then you very well may be getting the 491 cfm.

Also, though, I checked in Ed's spreadsheet and an orifice of 2.56" should flow 470 cfm. Now if that is the case I would think that your range 5 orifice would be more like 503 cfm or your inclined should be reading 95.8%

So what I think is if you calibrate your range 5 to 491 cfm then your inclined should be reading 95.8% for the 2.56 orifice at 28" h2o test pressure and that would be 470 cfm.

John

[49-1183904562]

Jake,

It would really help if you cold give us Inches on the incline as you may be multiplying your error if your % scale is off at all. (Please do not take me wrong I am not questioning your skills) it just makes the math easy and takes out the scale error if any.

Also I did not see this covered, but before you keep going you need to make sure your bench is level, the Depression Monometer is Plumb and you are very accurate in your incline angle. All of these things will add up to error.

Just some thoughts,

Also in the early part of the post it looks like a baffle or wall on the other side of the orifice. How close is it to the orifice?

Rick

[jakesportingservice]

Thanks Bruce and John for the help. I have not moved the bench since i started the calibration and i have verified that the inlcined matches the vertical at 13". I guess i should check it at other areas to make sure my layout was correct. I think what we have come up with is it is acting like a orifice in a pipe. The only reason i say this is because the larger the orifice is in the disk the worse the numbers are off which is way low I originally figured the disk should flow 443 cfm with the 13.03 dp on the inclined from the spreadsheet. John the plate that has the 2.56 hole in it i used a .60 cd at 28"
I have a orifice that i've flowed at work and that is where i originally came up with the .665 cd to match the cfm number of the plate that i flowed.
Does all of this sound right i was thinking that we were figuring it out but now i'm second guessing? Also i have verfied that the plate is about a 1/2" all the way around from the board that i mounted on top of the disk. I was thinking that if i had a board of equall thickness on each side of the disk the intake to exhaust difference would be closer than that of a blue bench. I read that on the forum somewhere so i tried it. I think it would work but i obviously didn't cut the holes big enough in the boards for the larger ranges. There are pics in my readers projects that show the angle board with the flowdisk.
Thanks for the help i will check somethings over and see what i can come up with.
Thanks Jake

[jfholm]

Jake,
I was at one time trying to do the orifice in a tube deal and noticed that the closer the orifice came to the tube id then the worse it got. If I did not let the orifice get any larger than 30% of the tube id it was not too bad.

If you stuck to those rules the holes in the boards on each side of your range 5 orifice should be at least 8.5" in diameter.

Now I can't remember where I saw it but it was on this forum stating that on intake with these orifice benches the flow was ok but when flowing the exhaust where there was a hole in the divider before the orifice there was some inaccuracy when the orifice itself got too large in comparison to the board dividing the two chambers where the orifice sits.

My solution to that is when I make my bench I am going to make the orifice plates larger square so when I maching the orifice hole there is more flat area around the orifice allowing me to make the hole in the divider board much larger.

John

[jakesportingservice]

Hello i've been messing with this thing tonite and was just wondering if i was coming up with my number by using the single plate that i flowed at work and checked the numbers on the spread sheet and that verified what it flowed. Does anybody think that this is the wrong way to get my range cfm?
I understand that i wont be able to use this for the smaller orifices in the disk.
Would anybody think it is a problem if i flowed a head at work and then compared the numbers to my bench?
I know this seems alot to ask with out being in front of the bench to figure it out but this is a great learning experience and i know that this is a great forum to be around.
I appreciate all the help that everyone is trying to give me if it weren't for the great people here this bench would not have been possible.

Thanks Jake

[jakesportingservice]

Hi John i think that you are absolutly correct and if i were to do this bench over or another i would just use the fixed orifice plate and stoppers but for now i think this can be figured out and there is very minimal leak on the intake as well as the exhaust with the disk completly trapped inbetween the two pieces of plywood. I understand now that the hole should have been twice the size as it is now.

Hi Rick I will try taping a measuring stick to the scale and see if that data corresponds with my %scale thanks for reminding me of that. I know that was read on here somewhere but had forgot to do that but now i will .
Is the inclined ok with the longer resevoir higher than the end of the scale ? Should this be even with it ? or does this not matter ?

Thanks Jake

[jakesportingservice]

Forgot to load pic the tube next to the switches i sthe one in question.

Thanks Jake

[jfholm]

Jake,
To me your incline manometer looks fine. Basically the same setup as mine only yours is nicer. I just made mine so I could change the angle a little so it would read the same as my Performance Trends Black box.

I took one of my heads to a friends shop and flowed it on a SF300 to get a starting point. He let me know at that time that his bench reads a little low. On his Super Flow and I also think on the SF600 to switch the flow direction there is a rotating carbon disc and that gets some wear in it after time. This lets the pressures to the inclined manometer bleed off a little so the inclined will not read as high as it should giving you a low reading. Keep that in mind when checking against the blue bench.

On the Performance Trends black box when using the Port Flow Analyzer software it lets you add a correction factor to each range so your bench will be spot on. You are asking if this is ok to do with your bench. Of course! I would make an orifice that would flow 75% to 80% for each one of your ranges. I used .060" aluminum plate and as close as I can tell they are around .616 or so cd. I just calculate what each diameter will be in CFM using Ed's spreadsheet. I then calibrate my bench with those because math does not lie. If I have to put a correction factor in the software it will let me. The bench will then read right on. Just remember to always keep your flow to at least 40% and I prefer to always keep it to 50% or higher when flowing. If it drops below 40% then I switch to another orifice so it will stay above 40% at least.

Now a plug for the electric gauges, as in what Bruce and Rick and Tony are working on. With those and this Black Box I have you can just use one orifice for all flows. I have verified this twice now with my Black Box. I flowed my head using my full range of orifices and the inclined water manometer and my Black Box. Next I flowed the head again just using my largest orifice and compared that to the first test. The readings with the inclined were off on the lower lift readings until I got above 40%. But the readings from the Black Box were still spot on. I don't know if it is the software or the box making this happen but I now always just flow with my largest orifice and do not worry about the inclined. Something to look forward to on Bruce's DAQ.

Now a plug for Bruce's orifices. I was doing my own but then bought on of Bruce's. His is a sharp edged orifice and mine were square edged. His is more repeatable and more stable. Bruce's style of orifice is what I am convinced now to used.

John

[jakesportingservice]

Thanks John that is what i needed to hear because i was almost to the point to rip the disk out and just use plates but for now i think i will play with it a little more and see if it is working ok if so i will just leave it alone . Thanks for your help i do appreciate it .


Thanks Jake

[jakesportingservice]

Hi to everyone i haven't had much time to play with the bench but i did some test with my orifice plates bolted right to the top of the bench and came up with some good results .

Now where i have a problem is when i have my cylinder head adaptor on the intake tests are very close to what the blue bench are at work but the exhaust tests are about 15 to 20 cfm low ? what i cant seem to figure out is that the calibration plate flow what it should with out the adptor on and i built the adaptor almost identical to the one that sf uses on there benchs except mine matches the bore size.

A buddy of mine was here helping and he said that my head was laying around and had gotten stail so i put his head on and show him that his was well on the way too!! I know that wasnt part of the problem but i thought i would share the humor .
Any anwers or comments would be appraciated
thanks Jake