I haven't been on here for ages. I have used a fairly unconventional bench for nearly a decade. It's an orifice-in-a-tube design much like Kevin's (Performance Trends) EZ-Flow design. 125mm tubing, that's 5" for you. I have industrial software that lets me calculate the accurate orifice flow according to the ISO 5167 standard to 3 decimals no matter the side wall effects and such, so knowing what flow I should have is no problem.
But. The problem now. I moved it, as in completely took it apart and moved it, now I am reassembling it to a slightly more compact form after a de-tour via a typical orifice bench, that showed too much flow at all times.. just like this now. I did not get the math to work out on it, but now it seems more like I have forgotten something about the setup of a bench as this current bench, although a very different design, shows the exact same numbers - too much flow for the test pressure - like the other one.
Now it's suddenly impossible to calibrate... so I wonder what I have forgot in the 7-8 years since last time. I did have this exact issue before too, just did not write it down back then...

Any ideas why it shows 100% Flow at 7.5" TP? It needs a rise of about 13" on the inclined to reach 10" test pressure on the vertical...

No leaks in the hoses. I have ran a leak test with the inclined at 12" rise that showed 2 cfm leak at 70" for the full system, hardly worth mentioning. The distance to the orifice from the last bend is about 5 feet, distance after the orifice is 8 times the tubing diameter, so that should be fine.
Any pointers? As I mentioned, the big-chambered "normal" flowbench I 99% finished before I gave up showed just the same. So what have I forgot??
