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Machinery space fire protection methods & Walter Kidde CO2 system

Machinery spaces are protected by fixed fire extinguishing installations, the fire main and extinguishers. Any statutory fixed installation must be operable from a position outside of the space. Any emergency stops for machinery and vent fans, means of securing openings and fuel tank valve shut-off devices, must also be located external to the space.

Machinery space fires

Engine room fires have been started by neglected oil leaks with the combustible material, in the form of fuel or lubricating oil dripping on to and being ignited by hot exhaust manifolds. There are a number of examples of combustible materials and potential ignition sources in machinery spaces. A fire when it starts is usually small enough to be dealt with by a vigilant watchkeeper using a portable fire extinguisher.

A fire which develops undetected in an unmanned machinery space (or one where the watchkeeper is in a control room) could require complete shutdown, evacuation and employment of the inert gas system. With unmanned spaces, an efficient alarm system for early detection is vital

Carbon dioxide system
Figure : Carbon dioxide system

Cargo ship fire main (R. C. Dean)
Figure : Cargo ship fire main (R. C. Dean)

Walter Kidde CO2 system

Figure 14.15 is a schematic layout of a Walter Kidde CO2 system in which pilot CO2 cylinders are used to open the distribution system main stop valve and subsequently the valves on the individual cylinders.

The system shown has two banks of cylinders. The pilot CO2 cylinders are contained in a control box and normally disconnected. To operate the system a flexible pipe fitted with a quick action coupling is plugged into a corresponding socket. When the valve on the pilot cylinder is opened the pilot CO2 will open the system main stop valve.

The stop valve actuator is a piston device and when the piston is fully depressed a second port is exposed which allows the pilot gas to flow to the CO2 cylinder bank and to operate the cylinder valves. As soon as the control cabinet door is opened to do this, the alarm is initiated. The position of the hoses in the quick-coupling housings prevents the door from being closed.

The pilot CO2 cylinders and the main CO2 cylinders for this system, are fitted with Klem valves.

An isometric sketch of a Klem valve fitted with a CO2 actuator is shown in Figure 14.16. The safety pin shown is for transporting the cylinders. When installed the safety pins are removed from the valves, allowing them to be operated manually or by pilot pressure. As soon as mechanical or pilot pressure is removed, the valve will close again. In this system each of the cylinders is fitted with a CO2 operated actuator.

CO2 fire extinguishing installation
Figure : CO2 fire extinguishing installation

Klem valve with pressure actuator
Figure :Klem valve with pressure actuator

Summarized below general cargo ship fire protection equipments & guideline:
  1. Fire main system & related mechanism

  2. The fire main extends to the full length of the ship and from the machinery spaces to the highest levels. Hydrants served by the main, are situated so that with suitable hoses any area on the ship can be reached. .....more

  3. CO2 fire extinguishing installation

  4. Fire extinguishing installations employing CO2 stored under pressure at ambient temperature are extensively used to protect ships' cargo compartments, boiler rooms and machinery spaces. When released the CO2 is distributed throughout the compartment, so diminishing the relative oxygen content and rendering the atmosphere inert. ...... more

  5. Fire fighting equipments

  6. Two independently powered pumps must be provided in all cargo ships of 1000 tons gross and over and in passenger ships of less than 4000 tons gross. Larger passenger vessels and passenger ferries must have three such pumps. The pumps are fitted with non-return valves if they are of the centrifugal type, to prevent loss of water back through open valves when not running. ..... more

  7. Details of fire detectors

  8. A variety of devices are available for detecting fire in unmanned machinery spaces but each has an ability to detect basically only one aspect. Thus, smoke detectors based on the ionization chamber are able to recognize combustion products but will not register radiation from a flame or heat. .....more

  9. Machinery space fire & use of Walter Kidde CO2 system

  10. Walter Kidde CO2 system employs pilot CO2 cylinders to open the distribution system main stop valve and subsequently the valves on the individual CO2 cylinders. .....more

  11. Fire protection system for cargo holds

  12. Holds for general cargo, have been protected against fire by fixed installations which deliver inert gas from an inert gas generator based on combustion of fuel (similar to the system available for inerting oil tankers) and halon systems. .....more

  13. Low pressure CO2 storage

  14. In some installations, the CO2 is stored in low pressure refrigerated tanks. The cylindrical storage vessels 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. ..... more

  15. Halon system

  16. Halon 1301 has the chemical formula CF3 Br being known as bromo-trifluoromethane. It is a colourless, odourless gas with a density five times that of air and extinguishes fire by breaking the combustion chain reaction. .....more

  17. Multi-spray system for the machinery spaces

  18. This system is similar to the sprinkler used in accommodation areas but the spray heads are not operated automatically. The section control valves (Figure 14.20) are opened by hand to supply water to the heads in one or more areas. Ready to use hoses can also be supplied. Fresh water is used for the initial charging and the system is brought to working pressure by means of the compressed air connection. .....more

  19. Automatic sprinkler system

  20. A network of sprinkler heads is arranged throughout the spaces to be protected. Each sprinkler head is normally kept closed by a quartzoid bulb which is almost filled with a liquid having a high expansion ratio. .....more

  21. Details various portable extinguishers & how to use ?

  22. The first line of defence against fire in any area of the ship, is the portable fire extinguisher. Some common portable extinguishers that have been used at sea are described. .....more

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