orifice plate leaking

[Nick]

Pilots belong in the seat holding the yoke.

Quote.

"Hey Nick, how do you wet flow the exhaust ports?

Do you suck through them or what?

I'm still trying to figure that out and could use a little advice....I'll probably suck through them so the cyclone separator can do it's job."

Jesse,

I don't know about you, but I prefer my engines to burn the fuel before it makes it to the exhaust port. Why would you wet flow an exhaust?

Here's an Idea, hook up your spark plug to a coil, and run air and fuel through the bench, and let here rip. Now that would be a show!!!!!!!!!!!!!!!!!!!!

"Quote"

"I could wet flow french fries with ketchup using this design and not pollute a pitot flow element. I want to be able to port the intake while the head is on the bench under vacuum. It would save time and be less messy."

I like it!!!


Nick

[Thomas Vaught]

Read my post in the wet flow bench forum.

Tom V.

[cboggs]

Guys,

sorry to interupt, .. :p

but back to the leaking orifice disc problem, .. ..

I'm going to replace the disc with a 14" x 14" plate with four holes in it.
And use rubber stoppers to change ranges.

CFM@28"
100 = 1.18"
200 = 1.67"
400 = 2.36"
603 = 2.9"

Just going to cut out a 12"x12" hole for the plate, .. and use the
deck plate to get into the front for changing the range.

seems simple enough, .. cause at this point I need to get it working
and get back to work on heads.

Curtis

[larrycavan]

That's 1300 potential CFM with enough motors..WOW!...you should be able to test my heads from your place!! :;):

[Thomas Vaught]

Sounds like a plan.

Tom V.

[Nick]

You may want to see if you can get a stopper 2.9" I have not seen one that big. My 2.513 takes a #13.5. You probably can, but it would be a bummer if you could not find one.

Your not going to have a Delta P of 28" are you? If you wanted to test at 40", that would be 68" that your motors would see. In the last few posts we talked about why that my not be good.

Also you said back at the begging you were going to use a Delta P of 12". So your calculations are not correct. Here is what they would be with a 12" Delta P and a CD of .62

1.18 =65.4
1.67 =131
2.36 =261.6
2.9 =395

That probably does not look the way you want.

The sizes need to be made according to your Delta P, not your test pressure.

Nick

[Jesse Lackman]

[Thomas Vaught]

On the large 600 cfm hole (13.85 DP with blue fluid) we could not find the large stopper easilt so we made a simple plug with a piece of aluminum and a "o-ring" The part looked like a T with the o-ring around the lower part of the T.

There are stoppers out there for a 400 cfm hole assuming 13.85 DP.

Tom V.

[86rocco]

Any particular reason you couldn't just make a stopper out of a fairly hard RTV silicone or polyurethane?

[DaveW]

[Mouse]

Pipe plugs from your local hardware store? They have turn screws on them that make them expand. Should be available in 1.5", 2", 3" and 4".

[cboggs]

[Thomas Vaught]

Curtis,

Looking at the Ametek data for 8 motors, it says that with 8 115923 motors there will be 48" H20
at 600 cfm. I am assuming this is through a standard 2" orifice.

If your valves are larger than 2" then the test pressure will drop accordingly.

You have 9 motors so you will pick up a little vacuum and you will pick up a little more cfm
(maybe 50 cfm) so You might be just fine at 40"

Hope this helps! If anyone else wants to jump in, please do.

Tom V.

[Terry_Zakis]

Hello Everyone,

I hope I'm looking at this correctly. I don't remember if the sheet I'm looking at was posted, but I'm now looking at my file "AmtkVac_115923_Parallel_061203.xls", Tab "OrificeFlow_Plots", (9th tab from the front), the Chart Date is 04/16/03, there are 4 motor plots for the 115923, being 4, 8, 12, or 16 motors. There are also 13 plots for various orifice sizes, and their Beta ratios (orifice diam / pipe inside diameter), and one plot for a 6-inch averaging pitot tube.

Using this chart, lets look at the 8-motor case, dark green diamond markers with dashed line. You will see that 8 of these motors will pull just over 600 cfm with a total depression of 50 inches w.c.. That's the total dp available to still get 600 cfm. The total consists of the orifice plate pressure drop, and the unit under test pressure drop, and any other internal drops through the bench, whether inlet or exhaust.

Now, from the horizontal 600 cfm flow line, you'll see that it crosses 6 different orifice combinations, and the 6-inch averaging pitot tube line. The 6" pipes with .6, .7, and .725 Betas will need orifice dp's of app. 10", 5", and 4" w.c. respectively for the orifice's alone. This would calc out to be orifice plates of 3.6", 4.2", and 4.35", for installation in a 6-inch pipe, which is what my orifice provers are based upon.

So you are correct in going to a larger orifice plate would chew up less of the total depression that motors would provide. In my design process, as you see on this chart, I also looked at larger pipe orifices (8-inch pipe, with .7, .725, and .75 Betas) and looked at the 6-inch averaging pitot tube.

So to use less dp across the orifice you'd go to the larger orifice, or the averaging pitot tube inside of a pipe. In setting up my orifices, I wanted to have two flow ranges, with either 10" or 20" across the orifice plates, and a separate calibration curve for each. I didn't want to go any lower than 10" across the orifice at max flow for a given range, because I wanted to maintain some decent dp at the lower flow levels.

If you're looking at a 2" orifice as mentioned, then it would correspond approximately to the 3" .7 Beta plot in this chart, and you'd only get about 200 cfm across that orifice at with a 20" pressure drop.

I'd encourage you to spend a little more time with this sheet and change the 8-motor case to 9-motors if you have to, but save it to a difference file name, and go through and rename the 8-motor plots to 9-motors.

If you want to dig deeper, you can look at the tabs ""Orifice_Flow_Ranges" which show flow ranges starting out with the max orifice dp, and determining the lower range based on the accepted 4:1 turndown ratio for orifice plates. This can help you determine what ratio or orifice diameter you want to settle in on.

Hope this helps,


Terry T.

[Thomas Vaught]

Terry,

Not knowing how the data was provided the (2"
orifice example) I mentioned was what I have read for how a SINGLE motor was tested.

Apparently your calcs are far more in depth.

I will look for the other tabs you provided.

My initial statement was based on the tab Vacuum
I believe with the 115923 motors and the resultant cfm vs motors. Vacuum on the "X" axis.

Thanks

Tom V.