What characterizes isokinetic sampling in the context of a gas air stream?

Isokinetic sampling is primarily characterized by its ability to achieve an equilibrium between the flow rates of the sampling probe and the surrounding gas air stream. This method is designed to collect samples that are representative of the gas stream being analyzed, particularly regarding particulate matter.

The correct answer reflects the principle of maintaining equal flow rates between the sampling probe and the gas stream. In an ideal isokinetic sampling scenario, the velocity of the air entering the probe matches that of the gas stream, effectively avoiding the bias that could occur from differences in flow rates. This matching of velocities ensures that particulates are sampled without a bias toward larger particles that may be preferentially collected if the sampling probe’s airflow were greater than that of the gas stream, which can lead to oversampling.

When conducted properly, isokinetic sampling maximizes the efficiency of sampling by accurately capturing the distribution of particles in the air stream, thus providing valid data for evaluating exposure levels. Maintaining equal flow rates prevents any skewed results that would misrepresent the true concentration and type of particulates present in the gas.