A closer look at the use of a portable infra-red analyzer for low-level hydrocarbon emissions

On-site use of a portable infra-red (IR) analyzer in successfully monitoring hydrocarbon vapours is discussed. The detection limit of the IR detector is much lower than that of other hydrocarbon vapour monitors and can be used in situations where, as in most ambient air, the levels are often less than one milligram per cubic meter. A more recent experiment was designed to include an upwind IR monitor, shortened sampling cycles to produce more data, and added canister samples collected outside the burn period. Results showed, that the IR analyzer was able to produce a near real-time distribution of the hydrocarbon vapours in the test emissions with a sampling cycle of only one minute. While the two methods are not exactly comparable, the indications are that the portable IR instrument could help to describe the hydrocarbon emissions downwind from a source, as well as monitor for these hydrocarbons on a continuous basis, including situations where the levels are below the detection limits of most portable detectors. 5 refs.,3 tabs., 4 figs, 2 appendices