lammert - 4:57 pm on Mar 1, 2010 (gmt 0)
Although the gases in Inergen do not damage electronics by themselfs, the release of it can. the gas mix relies on dilution of the oxygen in the air from 21% to about 10%. To do this you have to add about the same volume of gas to the room as already present. Without quick pressure release systems in the server room this will increase the pressure significantly upto 1 bar+. If you have ever opened a computer and looked at your harddisk, you will see that most harddisks are covered with a thin sheet of metal. A pressure surge of 1 bar will cause a force of about 100 kg (200 pounds) on that sheet of metal which will probably bend and damage the heads and other delicate mechanics inside.
Many older data centers were designed for use with Halon type fire suppression systems. Halon gases do not replace the oxygen in the air, but they catch the radical oxygen atoms to prevent them to bind with flamable substances. Much less gas is needed and there is not a significant pressure increase in the server room. Halons are now forbidden because they damage the Ozon layer around the Earth. Older data centers which moved from Halon to Inergen fire suppression systems may not have the adequate pressure release systems in place to prevent mechanical damage due to the pressure surge.