Calibrating FP1

[Mousehouse1]

I have a mercdog/msd bench. I am trying to calibrate my bench to the FP1 box and FPcomXL software.

I want to use three orifice sizes. Do I need to use all of the motors when I calibrate each hole or just enough to get to the 118.3 number on the orifice disk that came with the FP1?

I found out where to set the orifice sizes and how to adjust the cd but don't quite understand how.

I don't want to keep bugging John & Chad so I thought I would post it here.

[larrycavan]

It depends on the size of the orifice as to how many motors you need on.

If you're only just at or slightly above 118.3, turn on another motor just in case you start falling below when you adjust your Cd value.

If you're using 3 ranges then you'll have to decide how you want to enter them for intake and exhaust. Remember you'll be treating each individual orifice as two because the Cd will be different for Intake and Exhaust.

Hole one could use A [Intake] and B [Exhaust] or you could use A, B, C for intake and D, E, F for exhaust. What method you choose is entirely up to you.

Warm up the bench for a few minutes then start calibrating.

After you've entered your orifice diameters you begin the test. Adjust the Cd from the default .62 until you hit the 118.3 value.

Orifice Command - Corresponding Cd Command

A - G
B - H
C - I
D - J
E - K
F - L

Start with A, see what you have for CFM, enter G, set the cd value for A, repeat until you hit the number. REMEMBER the FP1 commands are case sensative!

If everything works properly it's like the Showtime oven....Set it and Forget it..

Hmmmm...maybe Ron will could build a bench and sell it on tv for three easy payments of $13.33....

Larry

[Mouse]

[Mousehouse1]

Thanks for the info. If I get time today I will play with the bench and FP1 a little more.

Is it a problem if I can't get the test pressure to stay at 28"? It seems I am just below it or just above it. If I turn on more motors I am above and less I am below. Is there a way to adjust the FP1 for test pressure?

[larrycavan]

If you can't hold 28" by adjusting your flow control valve, then you probably have a turbulence issue.

Attached is a picture looking down through my test fixture. All you see is a black plate that is about 1.5" below the discharge opening. What you can't see is just off to the left side of the hole is my test pressure probe. It's mounted on top of the black baffel plate on a 90* angle bracket. It's threaded into a hole in the bracket with lock nuts on both sides. The probe points straight toward the front of my bench.

This position on my bench seems to work well in obtaining steady pressure readings.

Larry

[larrycavan]

John,

How's the one way valve deal progressing?

Larry

[larrycavan]

John,

Do you have a way to dump the orifice into to the Excel sheet? It would be nice to be able to see that and the Cd right on the excel sheet.

Larry

[Mousehouse1]

My test pressure is stable but I forgot about adjusting the valve to make it go up or down.

I am just new at this and trying to figure out what to do. Since I got the bench running I haven't had a lot of time to mess with it. 10 minutes here, 20 minutes there. Just need some time with the bench and FP1.

What is the best way to determine if you have a leak?

I have one orifice hole that is 1.270" in diameter. With the calibration plate that John sent me attached to the bench I have to have all 8 motors on to get the bench a little over 28". Actually around 28.6". I don't have to have that many motors on to get to 28" with a 2.330 & 3.068" holes and the same calibration plate installed. I thought the smaller the orifice hole the less motors you would need to get to 28"?

Just running around in circles chasing my tail.

[larrycavan]

[larrycavan]

You're correct, the smaller the hole the less motors you should need.

Generally when one range behaves irratically, the reason is leakage at the flowdisk.

You can see through the front of your bench. Does it appear to you that air could be leaking from the orifices adjacent to your 1.2" orifice?

Can you seal the other ranges with some duct tape and test again?

[Mousehouse1]

I can get the smaller 1.270 hole calibrated but haven't been able to get the two bigger orifice holes calibrated. The only problem is to get 28" of pressure on the 1.270 orifice I had to use all 8 motors. I only had to use 5 motors on the 3.068 orifice to get 28" of pressure.

Here is the FP1 reading for the 3.068 orifice hole with 5 motors on.
28.0 25.5 25.2 4637

I didn't turn on all 8 and should have to see if the cfm readings went up. I will try that later. What would make the cfm readings so low? I didn't adjust the cd range any since the cfm readings were low.

I blocked off the calibration plate hole and turned enough motors on to get to 28". The FP1 showed all zeros across its readout. What is the best way to check leakage? Shouldn't the FP1 read something even if the intake hole is blocked off?

Larry I will check and see if I have the exhaust valve open any. It shouldn't be but at this point I am taking suggestions.

I have to be missing something or the bench is screwed up. I just have to find out which one.

[Mousehouse1]

Let me start from the beginning.

On my bench I have three brass tubes. Two of them are going into the front orifice disk area and one is going into the rear area. What tubes do the hoses from the FP1 go?

[Thomas Vaught]

On a normal Orifice Bench:

One of the tubes in the front cabinet goes to the test pressure manometer.

The second one goes to the Inclined manometer normally the "push"
side on the inclined manometer. John should be able to tell you on his deal which connection would normally "Tee" into that line.

The third probe (below the orifice) would go to the suction side of the orifice "Pull" side of the inclined manometer. Same deal from John here too.

I will look on the FP site and get back to you.

FP1 Connections =

FP1 + is the Upper chamber Inclined manometer connection, I believe,
for intake testing.

FP1 - Is the Lower Chamber Inclined Manometer connection for Intake testing

FP2 - I assume is the test pressure connection for the bench for Intake
testing.

Tom V.

[Mouse]

There is a drawing for connection to orifice style bench on this page.

[Mousehouse1]

Thanks Mouse. I think I had the PS2 lines crossed and they were going into the same chamber. I hope to have some time this coming week to set down and mess with my bench. Sorry for all of the trouble. No wonder my readings were so far off. I plumbed the lines wrong. I guess that is what I get for being excited about a couple of new toys.

I still get the same readings when I use the 3" orifice with the calibration plate after I made sure the hoses were where they were suppose to be. Plenty of pressure but the cfm numbers are to low.