Combining the transfer function of the dilution with the gas laws, it is fairly straightforward to get interesting functions that predict the effects due to changes in chemical and physical parameters and / or compensate for the effects of it. The compensation rules automatically act (when activated) in the logic of the diluter. However, it can be interesting for the user to know how it runs.
At the time of metrology certification, are measured the actual flows of gas to be diluted and the flow of the diluent gas in the diluter in correspondence to the 5 "main" dilution ratios : Known these 5 pairs of values,it's well determined the error "certificated " to qualify each dilution factor, which can then be internally compensated by the diluter logics.Download the "Certified errors" spreadsheet [67,7 kB ]
Diluting mixtures with viscosity significantly different from the diluent gas incurs a dilution error easily determined: this error can be compensated automatically by the same diluter, applying a pressures ratio equal to the ratio of the viscosity (for calculation of viscosity see the next document ).Download the "Different viscosities" spreadsheet [63,6 kB ]
We have automated the empirical formulas of Reichenberg and Carr (the first is the most accurate) to calculate the viscosity of a mixture, notes the main chemical-physical properties of the gases. The functions used to create this spreadsheet act automatically in the software InfoCAP30. We have verified that this is the page more "clicked" of the whole site, also by technicians who care nothing about gas dividers: we are pleased to offer this service.Download the "Viscosity of mixture" spreadsheet [126 kB ]
We did present in the "Articles" page an original procedure "Self-referring" for calibrating the 3 inputs gas divider BetaCAP30-3G : here you may find the involved calculations and results based from hypotetic errors values (that may be changed by the reader). This chart is the demonstration that the results don't change when the test bench conditions are changed (like applied pressure, flow measuring sensitivity) even when they change from test phase to test phaseDownload the "Self-referring Cal" spreadsheet [64 kB ]