Orifice Plate in a tube flow device - discussion on anything pertaining 2 this

[SWR]

[thomasvaught-1]

I come up with the same 132.1 cfm 100% manometer scale number at 12" orifice pressure using your calculated .633 discharge co-efficient. The beta ratio was .578 from the program using the square root of orifice area/ pipe area. Using the orifice divided by the tube diameter the ratio would have been .334

By Larry's example, a 3.6" diameter orifice in a 12" pipe would be a 30%
diameter ratio and a .548 Beta ratio. This will be interesting to sort out.

Tom V.

[106-1194218389]

[106-1194218389]

[larrycavan]

[106-1194218389]

Larry,
The orifice in a tube that I am playing with only uses the one tube. The last one I did I used with PT black box and only used the one orifice. That is my 4" tube. The new one I am building will be a 6" tube. Where the orifice plate goes is in a coupling that connects two 2' lengths of 6" PVC together. I leave the one side of the coupling unglued so I can change the orifice plates. I have honeycomb in the end of each tube to help strighten the air. One end has a 4" to 6" adaptor and that is where I mount the head fixture. The other end is where I hook the shop vacs. I'll try to upload a picture so you can see. It is really a very simple unit and very portable. I really do want to get my regular bench built from Bruce's plans, but I am also tinkering with this one. Something like the orifice in a tube that I am dealing with is very simple and quick to build. If I get it figured out a person could build the whole deal in a day if he had all the parts gathered. No, I don't feel like it would replace a regular bench, but for the little guy on a small budget it fills a need.

John

[SWR]

[larrycavan]

I guess I'm not generating an accurate mental picture of a setup with 4 or 5 orifices inside of pipes that are swappable in 8 seconds.....? ? ? That's really much faster that I had pictured it!

Ballpark pitot costs look like $45 per tube for pitot and static pickups, plus tubing cost. With pitot, you wont' need 12" diameter pipe. Looks less expensive to go pitot. Combine that with proven accuracy and the scales tip in that direction.

I believe the setup is workable but there is no clear advantage to it that I can see. I'm not trying to be closed minded about this. Just no evidence that it's cheaper or easier than anything else that's been built here.

JMO
Larry C

[thomasvaught-1]

A Cylinder Head/ Engine Developer named C.J. Batten (maybe you guys have heard of him) used multiple "orifice in PCV tubes" for his flow bench testing. He purchased calibrated orifices from Merriam, recessed the orifices in purpose designed flanges, etc. His benches used Paxton Superchargers and Merriam instrumentation.

Obviously he was in the cylinder head porting/ flow testing business. I am not saying that with today's electronics a Pitot set-up in a tube with a black box will not work fine but the "orifice in a tube" obviously did work for CJ.

Tom V.

[larrycavan]

[thomasvaught-1]

My example was only to show that others had good results with using "an orifice in a tube" style bench. I personally prefer the orifice plate in a cabinet style myself. I have seen benches where a series of orifices were installed in separate pipes and the "pipe run" went towards the ceiling of a high ceiling building without taking up much space. Food for thought, nothing more.

Tom V.

Having a bad day, Larry?

[larrycavan]

[106-1194218389]

The orifice in a tube that I am building is actually the easiest and cheapest one I am playing with. I also mentioned very portable. Right now it's low flow has not been as close as I want, but I have not used mutiple orifice plates. I have the ease in changing orifice plates figured out. Just a slip together coupling that I tape to seal. My total cost for this if I can get it to work will be around $100. You can just use a shop vac or two and still have vacuums for cleaning up.
Thing is you can just put it all in you car and away you go. I'll try to get some pictures uploaded. I just had some surgery on my neck and it will be a few days.

[larrycavan]

[106-1194218389]