These are systems that are installed with a sealed enclosure, typically a server room, LV/HV Room, Archives etc.
The fire suppression cylinders are often located within the enclosure or outside the enclosure. The basis of suppression is either removing oxygen or heat. These are both safe systems and suitable for occupied spaces.
reduce oxygen levels within the enclosure to about 12% to 14%. Combustion normally requires oxygen levels of 15% and above.
Humans can survive with oxygen levels from 10% and above.
The balance is making the fire suppression system safe and at the same time inerting the risk preventing combustion.
These come as brands, however, generally made up of a mixture of Nitrogen, Argon and in some cases small concentrations of CO2.
These systems use gases that attach to the free radicals of the heat source and reducing the kinetic energy of the fire, thus cooling it. The advantages are the lower concentrations are required and oxygen levels remain high.
These system are designed to suppress a fire a source. Often used in ATEX/hazardous applications. Typical applications would include commercial kitchens, conveyor systems, Hazchem baths and other risks that are not sited within an enclosure.
These can be referred to as Tube systems which comprise of a cylinder, capillary tube and end cap/pressure gauge. Designed for engine compartments, server racks, electrical cabinets and other enclosed local applications , these systems are inexpensive and automatic in their operation requiring no power source.