The application of gas-fire-suppression systems encounters a challenge that oxygen concentration tends to return to the original value in post-discharge time if open vents are present in a protected enclosure. Extending discharge becomes necessary to maintain oxygen concentration to prevent a fire resurgence in this enclosure. Until now the extended discharge rate must be evaluated individually by full-scale tests and no international standards specify the requirements in extended discharge. In this study, a formula was proposed to calculate the extended discharge rate as a function of opening size. A series of tests were conducted to investigate the oxygen concentration against the opening size in an apartment, followed by numerical simulations to recreate these tests. Then the discharge was extended in the simulations. Results show that the oxygen concentration was maintained between 10.5 % and 12.9 % in the apartment excepted the location next to the open door if the proposed discharge rate was adopted in the extended discharge time. Thus, this study proposal a universal method to quantify the extended discharge rate for a protected enclosure with openings.

气体灭火系统的应用遇到了一个挑战，即如果受保护的外壳中存在开放式通风口，则氧气浓度往往会在放电后恢复到原始值。有必要延长放电时间以维持氧气浓度，以防止该外壳内再次发生火灾。到目前为止，延长放电率必须通过全面测试单独评估，并且没有国际标准规定延长放电率的要求。在这项研究中，提出了一个公式来计算作为开口尺寸函数的扩展放电率。我们进行了一系列测试来研究公寓中氧气浓度与开口尺寸的关系，然后通过数值模拟来重现这些测试。然后在模拟中延长放电时间。结果显示，如果在延长的排放时间内采用建议的排放率，除靠近敞开的门的位置外，公寓内的氧气浓度保持在10.5%至12.9%之间。因此，本研究提出了一种通用方法来量化带开口的受保护外壳的扩展放电率。