Low pressure CO2 storage for Ship fire protection systems

Home page||Fire protection||

Low pressure CO2 storage for Ship fire protection systems

In some installations, the CO2 is stored in low pressure refrigerated tanks. The cylindrical storage vessels (Figure 14.17) are fabricated to the pressure vessel requirements of the authorities. The tanks are of low temperature steel, fully tested and stress relieved. They are mounted on supports designed to withstand shock from collision. The insulation to limit heat ingress into the CO2/ which is stored at a temperature of — 17 deg C, is polyurethane with fire resistant additives, foamed in situ.

Figure : Distillers low-pressure refrigerated storage tank

Figure : A CO2 fire extinguishing and smoke detector installation (The Walter Kidde Co. Ltd)

Figure : Klem valve with pressure actuator (The Walter Kidde Co. Ltd)

Two refrigeration compressors connected to separate evaporator coils mounted inside the pressure vessels, maintain the CO2 at the required temperature of — 17°C. One unit is sufficient to deal with heat ingress into the CO2 the other unit is a stand-by. Either water or air cooling can be arranged. The duty from main to stand-by unit can be reversed to equalize running hours, 'The instrument panel contains tank contents gauge, pressure gauge and alarms to indicate CO2 liquid level and pressure and also contains the refrigeration controls,

To ensure that a dangerous high pressure condition does not exist if a serious refrigeration fault develops, pressure relief valves are fitted discharging directly to atmosphere. The valves are mounted on a changeover valve and are set to discharge CO2 gas if the pressure in the vessel rises above the design pressure of 23.8 bar. Each valve can in turn be isolated for removal and periodic testing.

The vessels are fitted with a capacitance type continuous indicator together with a stand-by liquid level indicator which ensures that CO2 liquid level can always be checked approximately by opening the stand-by liquid level indicator valve which will flood the pipe to the same level as the pressure vessel. A frost line will appear due to the low temperature of the liquid CO,. Closing the valve will cause the CO2 to vaporize back into the pressure vessel The filling and balance lines are normally run to the main deck port and starboard sides for hose connections to be made to a road tanker. The balance line is used to equalize pressure with the tanker during the filling operation.

The liquid CO2 discharge is through a 150mm bore pipe fitted with an isolating valve but the quantity of CO2 discharged into the various spaces is controlled by timed opening of a discharge valve. A relief valve is fitted which will, relieve excess pressure in the discharge pipe should the isolating valve be closed with liquid CO2 trapped in the discharge manifold. Automatic or remote operation can be achieved by utilizing CO2 gas pressure from the top ot the tank as the operating medium.

Because of the considerably reduced amount of steel, the storage tank compared with cylinders gives an approximate 50% weight saving and because low pressure CO2 has a greater density than CO2 at ambient temperature, the volume it occupies is considerably less in terms of deck space. Also, low pressure CO usually costs considerably less than CO supplied in cylinders.

A periodical survey of the refrigeration compressors is required by the Classification Societies and this is limited normally to the exchange of pressure relief valves. At intervals of up to 10 years an internal inspection is required via the man-door provided.

Summarized below general cargo ship fire protection equipments & guideline:

Fire main system & related mechanism

.....more

CO2 fire extinguishing installation

...... more

Fire fighting equipments

..... more

Details of fire detectors

.....more

Machinery space fire & use of Walter Kidde CO2 system

.....more

Fire protection system for cargo holds

.....more

Low pressure CO2 storage

..... more

Halon system

.....more

Multi-spray system for the machinery spaces

.....more

Automatic sprinkler system

.....more

Details various portable extinguishers & how to use ?

.....more

Home page||Cooling ||Machinery||Services ||Valves ||Pumps ||Auxiliary Power ||Propeller shaft ||Steering gears ||Ship stabilizers||Refrigeration||Air conditioning ||Deck machinery||Fire protection||Ship design ||Home ||

General Cargo Ship.com provide information on cargo ships various machinery systems -handling procedures, on board safety measures and some basic knowledge of cargo ships that might be useful for people working on board and those who working in the terminal. For any remarks please Contact us

Copyright © 2010-2016 General Cargo Ship.com All rights reserved.
Terms and conditions of use
Read our privacy policy|| Home page||