Patent ID: 6640654
Filing Date: 2003-11-04
Classification: G01N

Abstract:
A device comprising:(a) at least two sample lines connected between a sample point and an air monitor; a converter in at least one sample line to convert a first chemical compound to a second chemical compound that is absent in at least one other sample line; (b) a plurality of control valves, each of the control valves between a sample line and the air monitoring device; (c) a timing generator for providing repeated on-off signals to each valve during a sampling time period, each on-off signal causing one valve to open and the other valves to close; and (d) a timing adjuster connected to the timing generator to ensure that the on-off signals from the timing generator to the valves are provided to open each valve for a proportion of the total sampling time period correlating to the proportion of the total sample volume to be collected from the sample line connected through that valve.