Answer SSEP Question 12

Q12. A. The fire protection provided for the propulsion motor and generator of a diesel electric drive vessel is usually one of the following methods:

i. Fixed foam extinguisher;

ii. Fixed CO2 system;

iii. Steam smothering system;

iv. Dry Chemical Powder

B. Briefly state in a comparative analysis, how each one of these methods has some disadvantages when used with propulsion system as stated above.

Answer: A. I. Fixed Foam Extinguisher:
Disadvantages
(1) A major problem associated with the use of low expansion foam as a fire frightening system in machinery space is that it is most effective only in the horizontal plane. Such a capability is valid only when the burning oil is conveniently held areas bounded by save all but for dangerous fires involving burst from fuel lines above the save all not effective.
(2) Certain amount of damage to machinery part particularly electrical fittings.
(3) Considerable entering period after use.
(4) Little cooling effect.
For High Expansion Foam Disadvantages are:
(1) Has to be cleaned after fire
(2) Skilled direction required to get best result in fire-fighting
(3) Restricts visibility
(4) Immersion of personnel for prolonged period may have debiliting effect
II. Fixed CO2 System
(1) Delay before application to allow evacuation by personnel.
(2) Quantity limited expect in case of refrigerated low pressure system.
(3) Relatively slow to inert in high engine room
(4) No cooling effect.
(5) Not effective in case sealing has been destroyed by explosion or other accidents.
(6) Grave risk of life in the event of accidental release or to person ring injured in protected space.
(7) Entry cannot be made from a considerable time without breathing apparatus.
III. Steam Smothering System
(1) While steam in its gaseous state is a good extinguishing medium in ship's system it may rapidly condense to form visible water particles and is not always effective as a smothering medium.
(2) Has a very limited cooling effect.
(3) Its higher temperature makes the control of smouldering fire somewhat protected.
(4) Damage to electrical machinery. it is now not accepted as a primary system.
IV. Dry chemical powder
(1) Can cause damage to delicate machinery by effecting electrical relay etc., and chocking narrow spaces.
(2) Not suitable for dealing with smouldering and deep seated fire.
(3) Little cooling effect, danger of reigniting.
(4) Toxic fumes can be produced under certain circumstance particularly in engine room. The powder can cause great discomfort to person not protected by breathing apparatus in relative confined areas.
(5) Powder mixture is subject to wind age may have reduced effect in open or ventilated spaces.