The battery-operated Dräger Flow Check Airflow Indicator electronically generates environmentally safe smoke for use during ventilation system testing. Carried by even the weakest airflow, Flow Check smoke indicates source, direction, and dispersion of air currents as well as relative air speed. The handheld Flow Check is ergonomically designed for easy one-hand operation. The instrument houses a replaceable ampoule that contains a special fluid mixture of alcohols. A small heating element at the head of the Flow Check heats the fluid, which condenses on contact with ambient air. The heating element temperature and quantity of ampoule fluid are electronically balanced. Flow Check is not suitable for respirator fit testing.