AGA X61902 represents a basic standard for safe operations and substantial and durable construction for diaphragm-type gas displacement meters having a gas flow rating of under 500 cubic feet per hour (14.2m3/h) at 0.5 inch water column (125 Pa) differential pressure at base conditions. This work is the result of years of experience, supplemented by extensive research. The standard is designed to ensure efficient performance and substantial construction of equipment.