Abstract: It is an object of the present invention to provide a gas generating device that can initiate the reaction of a liquid-reactive chemical at a specified time, and stop the supply of the reaction liquid at a specified time, so that generation of a gas by the liquid-reactive chemical can be promoted after workers have finished loading fruits, vegetables, or other produce into a treatment chamber, and a personnel-free sealed state has been formed in the treatment chamber.

Abstract: It is an object of the present invention to provide an inexpensive erectable tent having a simple structure in which the covering sheet can easily be removed from the structural framework assembly, and an airtight structure with respect to the surrounding atmosphere and ground surface can also easily be formed, in such a way that the air-tightness required for a hygienic gas treatment using a freshness-preserving gas or the like can easily be obtained.