Patent attributes
A particulate sampler system includes a diluted exhaust mass flow controller that receives flow from a dilution mass flow controller and a laminar flow element (LFE). The dilution mass flow controller and LFE are fluidly arranged parallel to one another. A controller communicates with the mass flow controllers and the LFE to determine the flow through these devices, command valves in the mass flow controllers and generate data for determining calibration coefficients and correction factors. The diluted exhaust mass flow controller is calibrated and calibration coefficients are generated using a first to fourth order curve fit. Similarly, initial calibration coefficients are generated for the dilution mass flow controller. The diluted exhaust mass flow controller is set at a desired flow point. The dilution mass flow controller is varied between set points corresponding to different dilution ratios at the common, desired set point. The data obtained is used to determine a correction factor for example, by performing a linear curve fit of the data. The correction factor is applied to the calibration coefficients associated with the mass flow controllers.
