Cfo 2010
The CFO 2010 is a Critical Flow Orifice, which will inject C3H8 into the CVS.
This CFO is built by me. The problem is to calibrate the orifice. This can be done with an volumetric reference, which is the easy way. Like the DryCal calibrator, these are however quite expensive. Therefore I made this calibration program, which uses an already available MFC, which has the range of 1000ml. A 24bit I/O measures the pressure, temperature and the analog out from the MFC.
Then the flow is calculated the same way as other calibration institute do the calibration.
I also interpolate the flow from the MFC with the calibration data of the MFC, which is calibrated every year. This eliminate the small error of the analog signal.
The Cp (specific heat) is recalculated in real time, and adjusts the MFC flow due to temperature offsets from Std.
It is also possible to zeroing the I/O and MFC signal before the actual calibration, to eliminate MFC drift and possible I/O zero error.
A typical calibration setup
The 24bit I/O
