This module, one of 25 on vocational education training for careers in environmental health occupations, contains self-instructional materials on using precision rotameters. Following guidelines for students and instructors and an introduction that explains what the student will learn are three lessons: (1) naming the parts of a low-flow precision rotameter and describing how each part functions; (2) disassembling, cleaning, and reassembling a low-flow precision rotameter; and (3) calibrating a precision rotameter, using a soapbubble meter. Each lesson contains objectives, recommended methods and locations for practice, performance criteria, equipment and supplies to perform a task, detailed step-by-step instructions for learning a task, and performance exercises. Two performance tests cover cleaning a precision rotameter and calibrating a precision rotameter. (CT)