My bench is coming apart.

[Thomas Vaught]

Nick, On the SF1200 we use occasionally at work I had a aluminum flat plate "stopper" with an "O-Ring" (with a weighted lead insert inside) made that will keep the "stopper" sealed to the orifice plate. That might also work on your exhaust testing.

Tom V.

The stopper is actually "T" shaped

[Nick]

My orifice plate is vertical, between two large settling chambers, so that won't work. But thanks for the Idea.
The bench is 6ft long 2ft wide and the top chamber is about 17.5" deep.

[gofaster]

Tom and Nick,
I want to thank both of you for taking the time to walk me through the basics. That pretty much explains the part that I was not comprehending. The formula I was using was not making any mention of two pressures, the test pressure and the delta p across the orifice. I had the idea that I was only concerned with the test depression across the orifice.
When I get to the shop on Monday, I'll try to find time to work with the excel spreadsheets and work it out. I'll post my results here on the forum so they can be checked out by the members. If I get right, it may help other builders who are having similar problems. If it's wrong, it may also help prevent someone from making the same mistake.

[Thomas Vaught]

No problem.

If you had a schematic of the flow path it would have been more clear earlier on. Glad we could help.

I think you will have a fine bench at some point.

Tom V.