User's Manual

General Information
September 2013 1-6 P/N 81-CO2MAN-001
discharged up through the siphon tube, valve, and distribution piping as a liquid under
pressure. The liquid is transformed into gas and the resulting expansion at the discharge nozzle
orifice and upon discharge a portion immediately flashes to vapor. The remaining liquid
undergoes continuous evaporation and cooling and eventually solidifies as finely divided dry
ice (snow) particles. The percentage of carbon dioxide converted to dry ice depends upon the
temperature of the stored liquid. Approximately 25 percent of the liquid stored at 70°F (21°C)
is converted to dry ice upon discharge. The dry ice particles gasify in a short period of time,
without passing through its liquid phase (sublimation), and no wetting or residue occurs.
The discharge of liquid carbon dioxide creates a white, cloudy appearance due to the dry ice
component. Because of the low discharge temperatures, some water vapor in the surrounding
air will condense, creating a temporary period of fog that lasts after the dry ice particles have
settled out or sublimed. The dry ice helps to reduce the high temperatures created by a fire.
It is important to avoid direct impingement of carbon dioxide onto people and very
temperature sensitive equipment.
Carbon dioxide vapor is approximately one and one-half times as dense as air at the same
temperature. An actual discharge of carbon dioxide gas is much more dense than the
surrounding air. This accounts for carbon dioxide's ability to replace the air above burning
surfaces and maintain an inert atmosphere for a period of time following its discharge.
1-6.4 Actuation Methods
Kidde Fire Systems recommends that carbon dioxide fire suppression systems have an
automatic actuation, and that the automatic actuation be supplemented by one or more modes
of manual actuation.
The quantity and type of detectors required for a particular application are governed by the
type of combustible products being protected. For example, flammable liquids burn in a
manner characterized by rapid flame progression and intense heat generation. Automatic heat
or flame detectors are the most appropriate fire detection methods for this type of hazard.
Electrical fires, on the other hand, progress much more slowly to the stages of ignition and
flame development, and frequently undergo relatively long periods of thermal degradation and
pyrolysis during which large quantities of particulate matter and smoke are generated.
Automatic smoke detectors, usually consisting of a cross-zoned system employing both
ionization and photoelectric principles, or high sensitivity smoke detection, are two examples
of methods typically employed for this application.
It is common practice to supplement automatic actuation by two modes of manual actuation
called the "normal manual control" and the "emergency manual control." The normal manual
control consists of a manually operated device located in close proximity to the equipment or
materials protected by the suppression system. Typically it consists of an electrical switch, or
a mechanical manually operated device designed to transmit a signal via a pull cable. The
emergency manual control is one or more fully mechanical devices that are located on the
control head(s) of the pilot cylinder(s) and other auxiliary components such as time delays and
directional (or stop) valves. Kidde Fire Systems control heads are equipped with a lever-
operated mechanism that serves as the "emergency manual control."
The "normal manual control" is designed to initiate the full operation of the system by one
manual action. It is the responsibility of the system designer to ensure that such action will not
result in immediate carbon-dioxide discharge into a normally occupied area. It is the
responsibility of the system operator to ensure that the protected area has been evacuated
prior to operating the "emergency manual control."
1-7 APPLICATIONS
Carbon dioxide fire suppression systems are used for a wide variety of industrial, commercial,
and marine applications.