Improvement in the applicability of the air tightness measurement using a sudden expansion of compressed air

Air tightness is an important parameter for both smoke suppression in a fire and for the energy efficiency of buildings. A transient method using a sudden expansion of compressed air (SECA) was recently introduced to measure the air tightness, or effective leakage area, with the least amount of labor or preparation. Although the feasibility of SECA has been reported, relevant experimental data has been limited to small leakage areas of up to 20 cm², which has not been sufficient to cover the leakage of rooms in buildings. In this study, a test room and the test module for SECA were modified and the basic equation of the transient method was improved. As a result, the application limit of the leakage area can be extended up to 700 cm², and further extension would be possible simply by increasing the chamber volume or its initial pressure. The experimental results of SECA can be related theoretically to the results of a steady method, and they were not affected by the volume of the room. The results of this study will help prove the most convenient measurements for air tightness and for the effective leakage areas in rooms and ventilation systems.