marine engineering

Home page||Fire protection||


Soda acid type fire extinguisher

The first line of defence against fire in any area of the ship, is the portable fire extinguisher. Soda-acid extinguisher (discharges water) is one of the common portable extinguisher that has been used at sea for many years.

Soda-acid extinguisher

A 9 litre soda-acid extinguisher is shown in Figure 14.29. It has a 1.63 mm thick steel shell approximately 180 mm dia. and 530 mm high. The shell ends are dished and welded or riveted to the wrapper plate. The shell must be capable of withstanding pressures of up to 14 bar in the event of a blockage occurring in the discharge nozzle.

Portable soda acid extinguisher
Figure :Portable soda acid extinguisher
Figure 14.29
A. Steel container E. Gunmental top cap H. Nozzle B. Neck ring f. Atmospheric valve I. Alkali level indicator C. Acid bottle cage G. Internal pipe J. Plunger D. Acid bottle

New casings are hydraulically tested to a pressure of 25 bar, for five minutes. The container is also subjected to a pressure test of 21 bar at four year intervals. Suspended from the neck of the container is a glass phial containing sulphuric acid.

The main body of the extinguisher contains sodium bicarbonate, an alkaline solution. The extinguisher must be kept upright when in use. The operator strikes the pin at the top to break the acid phial so that acid and alkali mix, to form carbon dioxide which forces the water (with the chemical remains) out of the discharge. The device must be held upright in use.

The chemical reaction is as follows:
H2SO4 + 2NaHCO3 = Na2SO4 + 2H2O + 2CO2

Many portable extinguishers are discharged and refilled yearly. When refilling a soda-acid extinguisher the screwed brass cap which offers internal access should be carefully examined, first to see that the cap seal is in good order and secondly to check that the small holes in the sides are clear. The purpose of the holes is to release any internal pressure before the cap is fully removed.

It is important to check that the ball valve F is free. This prevents liquid from rising up the internal pipe and dribbling from the nozzle in hot weather. When the appliance is operated the internal pressure closes this valve. If it is jammed open the appliance will not function correctly.

Before refilling the container, the internal pipe G should be checked to see that it is firmly attached to discharge nozzle and that it is not damaged. With all extinguishers chemicals are provided in kits, complete with re-charging instructions. Carbon dioxide and



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.
  1. Soda-acid extinguisher (discharges water)

  2. The main body of the Soda acid extinguisher contains sodium bicarbonate, an alkaline solution. The extinguisher must be kept upright when in use. The operator strikes the pin at the top to break the acid phial so that acid and alkali mix, to form carbon dioxide which forces the water (with the chemical remains) out of the discharge. The device must be held upright in use. .....more

  3. Foam portable extinguisher

  4. Mechanical Foam extinguisher is filled with water and contains an inner container with a small metal bottle of liquid carbon dioxide, surrounded by a plastic bag of foam making compound. .....more



  5. CO2 portable fire extinguisher

  6. While carbon dioxide is used in some extinguishers as an inert propellant the gas is also used extensively as a blanketing agent. The carbon dioxide is in liquid form and is at a pressure of 6 bar at 20 deg C necessitating a strong container. This type of extinguisher can only be recharged ashore. .....more

  7. Dry powder portable extinguisher

  8. This type of extinguisher contains sodium bicarbonate powder with a water proofing agent such as magnesium stearate to prevent caking. The container shown holds a cartridge containing liquid carbon dioxide. On piercing its seal with the plunger pin, the gas is delivered through a tube to the bottom of the casing where it entrains the dry powder and carries it up through the discharge tube. .....more

    Portable halon extinguisher The use of halon in portable extinguishers should be discontinued when suitable alternatives are available because of the high ozone depletion potential.



Summarized below more 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



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||