primary and secondary chamber volumes

[Greenlight]

When I input your values into the spreadsheet:

Inlet Diameter 11.8" (~300mm)
Orifice Diameter 0.5047" (~12.82mm)
Delta P 3.28 H2O" (~83.25 mm H2O")

I get a compressibility factor of ~ 0.99 and a Reynolds number of ~4.83 x 10^2. Even though the chart does not show a Beta value of 0.043 or Reynolds numbers that low, you can visualize that the curve tends to trend upward very quickly at low Reynolds numbers. So, from my graph you can't accurately determine a Cd.

Even when I input the 11.98 H2O" (~304 mm) I get a Reynolds number that is 9.42 x 10^2, which again does not show up on the chart and therefore you can't accurately determine the Cd.

These Reynolds numbers are really low, an indication of very slow moving laminer flow.

Can I ask, what CFM (l/min) flow rates are you trying to accurately predict?

[Thomas Vaught]

Quote:

"If it is non linear, is it corrected for, or is it why the top 20% of each range is the part considered accurate ?"

There is a "sweet spot" on the orifice graph for highest accuracy.

SF uses that info and makes the orifice diameters and flow rates fall with-in that "flat - linear" section of the curve.

Tom V.

[jsa]

[Greenlight]

[jsa]

[jsa]

Greenlight,

I've googled reynolds number calculators and tried a couple, they seem to give different results to your spreadsheet.

Of particular interest is this free online one which does what your spreadsheet does, however it comes up with different numbers for ReD.



Give it a try and tell me what you think.

[laser3kw]

where can I find this spreadsheet?

[jsa]