Fire

Question 1

What is the safety procedure that a C/E should adopt with reference to Contractors working on CO2 systems?

Answer 1

See certificates to ensure they are competent
Safety briefing
Establish a time frame
Assign a member of staff
Appropirate isolation of CO2 system
Thus no hot work as the fire fighting capacity has reduced
Ensure fire fighting systems are working

Question 2

What factors should be consider before re-entry after CO2 release?

Answer 2

Observe a significant temperature drop by measuring the bulkhead
BA team to check the fire is extinguished
Ventilate and test atmosphere

Question 3

What is the explosive limits?

Answer 3

The Explosive limits are the Lower explosive limit and Upper explosive limit. Within the two there is a suitable concentration for ignition. Above or below the respective limit the concentration will be too rich or too lean to ignite

Question 4

What is vapor pressure?

Answer 4

Vapor pressure is the pressure exerted by a substance as it changes phase from liquid to vapor

Question 5

What is Flash point?

Answer 5

Flash point is the minimum temperature in which substance gives off sufficient vapor that can be ignited in the presence of an ignition source

Question 6

How can a cargo tank be maintain for an explosive state?

Answer 6

By using treated flue gas from the boiler which has 5% O2 to reduce the O2 level in the tank. The inerting gas should reduce the O2 content to below 8% as per SOLAS. This ensures the concentration in the tank is below the lower explosive limit.

Question 7

Why Compressed air should not be used to blow through the CO2 line?

Answer 7

Compressed air should not be used as it contains contaminates such as oil and moisture which can cause corrosion, this has the potential to create a hole in the pipe which could be deadly in the event of CO2 release. Additionally, the moisture can freeze when the CO2 is released therefore blocking the orifices.

Question 8

What CO2 maintenance is there?

Answer 8

Weekly:
Ensure securing of bottles
Visual inspection of system ensure valves are in correct position

Monthly:
Liquid level on bottles - using ultrasound sensors
Visual inspection of all pipe work
Bottle are properly secured
All discharge pipes are in place
Alarms are in place and not damaged

Annual:
Boundaries of the protected space should be checked to ensure the system would not be rendered useless
Functionality test of audible and visual alarms

Two yearly:
Blow line with dry compressed air or nitrogen
Ensure bottles have 95% charge - weigh or ultrasound level

5 years:
Internal inspection of control valves

10 years:
Hydrostatic test of cylinders
Replace hoses

Question 9

Walk me through a CO2 release?

Answer 9

Decision is made to use CO2
Ensure EDG is running
Ensure Ventilation is off and dampers closed
Machinery is closed
QCV are closed
Muster at CO2 muster station
Man CO2 room
Head count (Confirmation of everyone)
Notify Master
Request to release
Opening of directional valve
Opening of release valve after time delay
Re entry into CO2 room with BA gear to confirm release

Question 10

Economizer fire

Question 11

Scavenge Fire

Question 12

What is a CO2 siphon tube?

Answer 12

Ensures the CO2 leaves the bottle as liquid, because if the change of phase occurred in the bottle it could freeze the orifice

Question 13

CO2 bottle pressure

Answer 13

58.5 bar at 20 degrees