electrical equipment. The nondamaging quality
of this agent makes it useful as an extinguishing
agent for computer rooms and computer tape
There are two general types of carbon diox-
ide extinguishing systems, high pressure and low
In the high-pressure system, high-pressure
cylinders are used to store liquid carbon dioxide
at ambient temperatures (fig. 8-30). Normal
cylinder pressure is nominally 600 psi and varies
with the ambient temperature of the storage area.
Storage area ambient temperatures should not ex-
ceed 130°F or be less than 32°F. For safety pur-
poses, high-pressure cylinders have a frangible
disk that will burst at 3,000 psi to prevent cylinder
rupture as a result of overpressurization.
Low-pressure systems have a pressure vessel
maintained at 0°F by insulation and refrigeration
equipment (fig. 8-31). At this temperature, the
pressure in the container is approximately 300
psi. Because the container is kept at a low
temperature, the container can be filled to 90 to
95 percent of capacity. For safety purposes a relief
Figure 8-31.Refrigerated low-pressure C02 storage tank.