What is the purpose of the airflow indicator system designated HF?

• A. Filters contaminants from the air
• B. Provides a means of monitoring and measuring the velocity of airflow through an exhaust ventilation duct
• C. Regulates humidity in the space
• D. Controls the temperature of the exhaust air

Answer: (B)

Measuring how fast air moves in the exhaust duct is what this airflow indicator system is designed to do. It provides a readout or signal of the air velocity, so you can verify the exhaust is moving at the required rate to effectively remove fumes or hazards like H2S from the space. This ongoing visibility allows you to detect when the duct is blocked, a fan isn't operating correctly, or the system needs adjustment, ensuring safe, proper ventilation. It isn’t a filter that cleans contaminants, it doesn’t regulate humidity, and it doesn’t control temperature—the roles of those components are handled by other equipment.