1.    When the gas fire extinguishing system is started, a large amount of fire extinguishing gas will be sprayed into the protective area, and the air pressure in the protective area will instantly increase.    In addition, the heat generated by fire combustion can also increase indoor air pressure.    The larger the fire and the longer it lasts during spraying, the greater the increase in air pressure.    Therefore, the "Specification" requires that the allowable pressure (internal and external pressure difference) for the enclosure structure of the protective zone (including doors and windows) to withstand internal pressure should not be less than 1200Pa.    The allowable pressure for the enclosure structure of the protective zone to withstand internal pressure should be determined by the architectural and structural design professionals.

2.    The function of the pressure relief port in Jiangxi is twofold: on one hand, when the pressure of the fire extinguishing agent spray in the protective area rises to an appropriate value, some air and fire extinguishing agent are released out of the protective area through the pressure relief port in a timely manner to ensure the safety of the protective area enclosure structure;
On the other hand, it is necessary to prevent the failure of fire extinguishing due to the explosion of doors and windows caused by the increase in pressure during the spraying of fire extinguishing agents in the protective area, which could lead to the uncontrolled spread of the fire.

3.    Due to the heavier weight of heptafluoropropane, carbon dioxide, trifluoromethane, and hexafluoropropane fire extinguishing agents compared to air, in order to reduce the loss of fire extinguishing agents from the Jiangxi pressure relief port, the "Regulations" stipulate that the Jiangxi pressure relief port of the above-mentioned gas fire extinguishing system should be opened at more than 2/3 of the net height of the protective zone, that is,    the height of the lower edge of the pressure relief port should not be lower than 2/3 of the net height of the protective zone.