scope:

INTRODUCTION

In 1971 in recognition of the important relationship between the measurement and the effective control of air pollution, American Society for Testing and Materials (ASTM) initiated a pioneering program, designated Project Threshold, to validate methods for measuring contaminants in the ambient atmosphere and in source emissions. The first phase of the program was devoted to evaluation of methods for measuring the content of nitrogen dioxide (D 1607-69), sulfur dioxide (D 2914-70T), dustfall (D 1739-70), total sulfation (D 2010-65), particulate matter (D 1704-61), and lead CD 3112) in the atmosphere ^(1-5)*.

Methods for the measurement of the relative density of black smoke (D 3211-75T)⁽⁶⁾, oxides of nitrogen (D 1608-60), sulfur oxides (D 3226-73T, particulates (D 2928), and particulates and collected residue (proposed method)in source emissions have been evaluated in Phase 2 of Project Threshold.

The interlaboratory "round-robin" approach has been applied to Project Threshold by bringing together groups of competent laboratories for concurrent performance of the test procedures under actual field conditions. Each participating laboratory is responsible for providing personnel and equipment, assembling apparatus, sampling, and analyzing collected samples either on-site or at their own facility. The coordination of the testing program, statistical analysis of the data, and evaluation of the measurement methods based on the experimental results has been performed by Battelle's Columbus Laboratories.

This report presents the results obtained from an experimental study of the precision of measurements of the average velocity of stack gases using ASTM Method D 3154-72 (pitot Tube Method)⁽⁷⁾. The study was performed in conjunction with evaluation of methods for measurement of particulates and collected residue in source emissions.

*References are given on Page 40.