ANSI/ASHRAE 41.7-2025

Standard Methods for Gas Flow Measurement

Prescribes methods for gas flow measurement. Applies to laboratory and field gas flow measurement for testing heating, ventilating, air-conditioning, and refrigerating systems and components. This standard is restricted to applications where the entire flow stream of gas enters and exits the gas flowmeter in a gas-only state during data recording with the following exceptions: a) This standard does not apply to airflow measurements at pressures within this range: –25 kPa to +25 kPa (–100 in. of water to +100 in. of water) referenced to ambient pressure. Those measurements are within the scope of ANSI/ASHRAE Standard 41.2.1, b) This standard does not apply to fan performance rating airflow measurements. Those measurements are within the scope of ANSI/ASHRAE Standard 51.2 and c) This standard does not apply to gaseous-phase refrigerant mass flow measurements where the gas flow includes circulating lubricant. Those measurements are within the scope of ANSI/ASHRAE Standard 41.10.3. Dual units of measurement.