In order to change the test of closed water for the high pressure vessel for the closed air test, according to the requirement of airtightness for high pressure vessel,the quantitative mathematical model for closed water test was built by analysis of free going out for small orifices in fluid mechanics.

Points out that improving the system tightness and energy efficiency in operation is the developing direction of the industry.

The destruction of the defending obturation of all kinds of pipelines through walls and floors in civil air defense engineering under explosion shock waves is currently focused on.

This article explains the system design of cabinets,and specifically for special working environment of ship-born electronic equipment the airtight design,the thermal design and the EMC design of ship-born airtight cabinet of cast alloy aluminum are described.