Q7 (16 Marks) Safety & Fire Protection 🔥 Repeated 4x in exams
MEP • Written Exam

With reference to fixed CO₂ system for fighting machinery space fires:

(a) sketch a CO₂ bottled system. (6)

(b) How the number of CO₂ bottles required for ship is calculated? (4)

(c) explain how the system sketched in part (a) is protected from overpressure (3)

(d) Describe the periodic maintenance required. (3)

Appeared In: Aug 2026Mar 2025Dec 2023Aug 2022

Verified Model Answer (Text Solution)

Structured for DG Shipping MEO Class II examination scoring criteria.

Exam Ready
Part (a)

The CO2 flooding system floods the protected space under fire with carbon dioxide, which displaces air, thereby removing one leg of fire triangle for the extinction of fire. CO2 flooding system consist of main CO2 bottles, common manifold, master valve or distribution valve and distribution pipe lines with nozzles as shown in the figure below.

Part (b)
Part (c)

Each cylinder must be fitted with a bursting disc that will operate at about 190 bar preventing overpressure. If the bursting disc operates, the gas is released into the manifold. An alarm should be activated to indicate the high pressure in the system so that the problem can be found. The master valve will prevent the gas from reaching the engine room, and it is dispersed safely to the atmosphere by the relief valve on the manifold.

Part (d)

Maintenance of CO2 System

Things to follow before carrying out maintenance,

  • Inform the bridge before going inside the CO2 room.
  • Start ventilation blowers first and the room should be ventilated for some time.
  • Go with a person with proper communication equipment.

Weekly

  • Check all cylinders are properly secured.
  • Make sure that nothing has been placed to interfere with the normal operation of the system
  • Check all the operating levers and their accessories are properly tight.
  • Check clamping.
  • Check valve actuator.

Once every month

  • All the weekly checks
  • Inspect for piping and equipment for mechanical breakage
  • Operate the valve several times and make sure that it does not stick
  • Open the cabinet door and check the alarm and ventilation cut off working.

Once In Every Year

  • All the monthly checks
  • Cylinder should be weighed to determine the CO2 content
  • If the net weight is decreased by 10% of the actual weight, the cylinder should be recharged

Once In Every Two Years

  • All the checks in yearly
  • Blow through all piping with service air @ 25 bar pressure or Co2 to make sure that the line is not blocked

Once In Every Five Year

  • All the above
  • Spring loaded relief valve pressure test @ 180 bar.

10 Yearly

  • Cylinder pressure test @ 250 bar (after the first 10 years, the cylinder is to be pressure tested every 5 years)

15 yearly

  • Pressure testing of the line by a suitable liquid
  • Cylinder to master valve: @ 170 bar
  • Master valve to E/R or Cargo hold valve: @ 80 bar
  • E/R or Cargo hold to nozzle: @ 6-7 bar
← Back to MEP Question Bank Upload Recent Question Paper →