title: Directly digital flow controller.
abstract: An improved directly digital flow controller is evaluated for its ability to modulate gas flow rates. As in the older device, the "GasDAC" (named for its similarity to a weighted-resistor digital-to-analog converter) is capable of controlling gas flow in a linear and reproducible manner with the advantage of having an adjustable range of flow rates. The new design incorporates venting to prevent "puffing" when the individual flow channels are opened. The temporal characteristics of the GasDAC are also examined; modulation frequencies of 10 Hz with various types of waveforms are possible with the new device.
authors.affiliation: Department of Chemistry, Indiana University, Bloomington, IN 47405, USA.
authors.forename: Denise M
authors.initials: DM
authors.lastname: McClenathan
authors.forename: Andrew
authors.initials: A
authors.lastname: Alexander
authors.forename: John
authors.initials: J
authors.lastname: Poehlman
authors.forename: Gary M
authors.initials: GM
authors.lastname: Hieftje
mesh_terms: D000703:Analog-Digital Conversion; D001709:Biotechnology / Q000295:instrumentation / Q000379:methods*; D002138:Calibration; D004867:Equipment Design; D005740:Gases; D016014:Linear Models; D012212:Rheology; D013997:Time Factors
chemical_list: D005740:Gases