LPCO2 Fire Suppression System

G Fire low pressure CO2 systems are intended for use where large machinery and cargo spaces require protection with carbon dioxide. The advantage of the low pressure system is that one single tank replaces a large number of CO2 cylinders with an approximate saving of 50% in weight. The tank, main valves, distribution valves, refrigerators, and associated controls are supplied prewired and ready assembled on a common steel frame.

The quantity of carbon dioxide is shown directly by an electronic gauge indicating the actual tons of CO2 in the tank. The gauge unit is fitted with alarm contacts for warning at low CO2 contents in the tank. Recharging after use is made directly from a truck.

For large vessels the installation cost of a low pressure CO2 system is considerably lower compared to the installation costs of a high pressure CO2 system.

The system is designed to meet the requirements of the appropri­ate classification societies to which the vessel is being built.


The tank is constructed as a steel pressure vessel in accordance with the classification society requirements. The tank is equipped with two safety valves, which are fitted to a three way change-over valve, thus one safety valve is connected to the vessel if the other one is out of operation. The tank unit is supplied complete and ready for use, installed on a rectangular steel framework and held in position by thermally insulated supports. The tank is insulated with non-flammable polyurethane foam protected by an aluminium cover.

Refrigeration units

The refrigeration units are installed at the end of the tank on the support frame and are completely duplicated both mechani­cally and electrically. The refrigerant is environmentally friendly and the cooling circuits on the compressors and condensers are suitable for either seawater, fresh water or air-cooling. The tank is maintained at a temperature of –18°C, which is equivalent to a CO2 storage pressure of 2.1 MPa.

CO2 level indication

An electrical capacitance type liquid gauge is fitted and the meter is calibrated from zero tank contents to tank full. The indicator has an accuracy of +/- 2% and is fitted with an alarm switch indicating minimum filling level.

To meet rule requirements an overfill valve and a level sight tube with isolation valve is fitted.


A pre-wired operating panel is installed at the end of the tank on the support frame, at which are grouped all controls and overload relays for the refrigerators, tank pressure, level indicators, and various indicators and warning lamps. The panel is completely watertight and fitted with cable glands.

Valves and filling connections

The automatically operated main valve and distribution valves are ball valves fitted with manual override. The valves are sized so that the appropriate quantity of carbon dioxide will be discharged in accordance with the rule requirements. To prevent ice formation on the valves the main outlet pipe from the tank is located at the top of the tank as a continuation of the tank dip tube. The tank is filled by a truck through twin filling and balancing lines led from the tank to deck level port and/or starboard. Isolation valves and hose connections are fitted to these lines.

Release of carbon dioxide

Remote release of the required quantity of gas to a particular space is made from master control boxes located as required. The release system utilises the CO2 pressure from the tank to actuate the main valve and the distribution valve via pressure operated control valve, and these valves are arranged for remote operation from the master control box. When the appropriate quantity of carbon dioxide has been discharged, the distribution valve is closed automatically by means of a solenoid operated control valve actuated by the electronic timer.

Distribution system

The distribution valve is connected to a computer calculated piping system within the protected space and to which the CO2 nozzles are connected. The piping is dimensioned so that the required quantity of gas will be discharged within the prescribed time and at no point in the piping system will the pressure fall below 1.05 MPa which would cause freezing at the nozzles.

All designs and sizes are available on request

Low pressure carbon dioxide (CO2) systems are specialized fire suppression systems designed to maintain the carbon dioxide supply at 0° F and 300 psig in an insulated, refrigerated pressure storage unit. These storage units contain the amount of CO2 required to stop fire.

In Control Systems’ Low Pressure CO2 Fire Suppression Systems are Factory Mutual approved to meet all present codes and standards.

We offer complete equipment/engineering packages or complete turnkey installations including detection and control systems. Our product line includes horizontal and vertical tanks ranging in sizes from 3/4 ton to 60 tons, ½” through 8” master/selector valves, and a complete line of total flood and local application nozzles that can protect from 2 feet above the hazard up to 20 feet above the hazard.


Our low pressure carbon dioxide system is stored mostly as a liquid at approximately 300 psi (2070 kPa) and 0ºF (- 17.8ºC). It is maintained at this pressure and temperature by mechanical refrigeration. When needed, operation of the refrigeration system cools and condenses CO2 vapor in the vapor space of the unit, thus converting it to liquid and reducing the pressure. The storage unit is very well insulated, keeping to a minimum the heat transfer to the CO2 from the warmer ambient air of the storage location. A slight rise in storage pressure from this heat input starts the refrigeration cycle described herein. Stored as a liquid at an ambient temperature of 70ºF (21ºC) carbon dioxide has a vapor pressure of approximately 850 psi (5865 kPa). Thus, high pressure cylinders are used for storage, designated as High Pressure CO2. This brochure explains low pressure storage and describes the wide range of storage units available. The storage of CO2 in the “Low Pressure” state has numerous advantages over cylinder storage.


Effective: Low pressure CO2 is effective on a wide range of flammable and combustible materials in both surface and deep-seated fires, which adds up to greater uniformity and predictability.

Fast: Carbon dioxide is a colorless and odorless three-dimensional clean agent. Within seconds, it penetrates the entire hazard area to smother combustion.

Non-damaging: CO2 is normally harmless to equipment, materials and property. It does not cause spoilage, requires no clean up and leaves no residue, thus minimizing downtime after a fire.

Non-conductive: CO2 does not conduct electricity and is three-dimensional.

Economical: When a hazard requires multiple discharges or when CO2 requirements exceed 4000 lbs. (1818 kg) of agent [2000 lbs. (909 kg) for main discharge and 2000 lbs. (909 kg) for reserve], the overall system cost is less than a high pressure CO2 system.

Efficient: Low pressure CO2 chokes off combustion quickly. The dry ice “snow” in the discharge allows “local application” protection of non-enclosed hazards.

Compact: Storage units are compact and often installed outdoors to conserve floor space. Capacities range from 1-1/4 tons (1.13 MT) to 60 tons (54.5 MT) or more.


Typical hazards protected by carbon dioxide systems are:

  • • Printing Plants • Transformer Vaults/Electrical Cabinets • Power Plants • Dip Tanks • Rolling Mills • Coating Machines • Exhaust and Fume Handling Systems • Flammable Gas or Liquid Storage Areas • Generators • Inerting Applications • Coal handling, grinding, and storage systems • Data processing centers • Flammable materials storage • Shipboard machinery spaces and cargo holds • Telecommunications


Carbon dioxide is a standard commercial product that is commonly used for carbonated beverages, for fast freezing food, for medical purposes, for purging pipes and tanks, as well as for extinguishing fires. It is readily available in most cities and seaports throughout the world. For more than 80 years carbon dioxide has been used for fire protection purposes. The NFPA standard for fire extinguishing systems was initiated in 1928 and was first adopted in 1929. It has been revised approximately 26 times since, and represents the accumulated knowledge and experience of those who have designed and used CO2 systems for fire extinguishing purposes.


We would love to have one of our engineers work with you in customizing the perfect Low Pressure CO2 fire solution. If you would like a quote or additional information, fill out the form below and we will contact you directly.