9 TESTING AND MEASURING EQUIPMENT FOR USE IN TESTING THE PERFORMANCE AND EFFICIENCY OF POWER PLANT EQUIPMENT, NAMELY, ISOKINETIC COAL SAMPLERS, DIRTY-AIR VELOCITY PROBES, FLUE-INSERTED FLYASH SAMPLER, FORWARD-REVERSE PITOT TUBE, COARSE PARTICLE GUIDE CLASSIFER BLADES, AND AIRFLOW MEASURING DEVICES