Development of a Practical Source Sampling Slide Rule

Abstract

Historically, use of the nomograph to calculate isokinetic sampling rates for an EPA train has been cumbersome and awkward. In sampling situations where nomograph assumptions are not applicable, e.g., pitot tube coefficient not 0.85, dry molecular weight not 29, or where the ranges available are inadequate, e.g., stack moisture content greater than 50%, orifice meter constant less than one, the sampler cannot use the nomograph and must resort to other means for isokinetic determinations. The recent introductions of slide rule type calculators have offered some relief, but they still have inadequate capabilities and in addition, are difficult to learn and time consuming to use. The only sure alternative has been the equations. However, the equations for nozzle selection and sampling rate are not readily available in useable form in the literature. They are therefore presented in this paper with explanations.