The importance of ventilation on ships
Ventilation on ships as in land buildings comprises a network of ducts through which air is forced by fans. It is not essential or desirable that there is a single ventilation system and it is important that parts can be shut off as required for a variety of purposes.
Ventilation is covered in SOLAS in many aspects. First and foremost the structural elements and particularly ducting and its routing through bulkheads and decks are considered. That this should be so is understandable given that any penetration of bulkheads and decks are potential conduits for fire and flooding. Most of this will be addressed at the design stage and as part of the construction will be covered by the Safety Construction certificates.
Turning to the purpose of ventilation and its operation and management, this too is covered in SOLAS where for example SOLAS II-2 Regulation 4 includes provision for ventilation of machinery spaces sufficient under normal conditions to prevent accumulation of oil vapour.
Elsewhere in SOLAS there are requirements for means of control of ventilating systems and closing them as necessary to prevent the spread of fire. Ventilation is important in the control of fire and in dealing with it’s after effects. SOLAS II-2 Regulation 9, section 7 covers many aspects including the type of materials allowed to be used in ventilation systems.
SOLAS requires that the main inlets and outlets of all ventilation systems shall be capable of being closed from outside the spaces being ventilated. The means of closing shall be easily accessible as well as prominently and permanently marked and shall indicate whether the shut-off is open or closed and also that power ventilation of accommodation spaces, service spaces, cargo spaces, control stations and machinery spaces shall be capable of being stopped from an easily accessible position outside the space being served.
This position shall not be readily cut off in the event of a fire in the spaces served. There are also requirements that ventilation openings on the open deck should be protected and not a source of hazardous atmosphere being inducted into the vessel.
An aspect of ventilation that often attracts Port State Control attention is the condition of fire dampers. These are often kept open and as a consequence may become seized in the open position. In the event that CO2 is released to control an engine room fire, an open damper could make that ineffective and endanger the ship. Following an investigation into causes of PSC detentions, classification society DNV GL issued the following advice:-
The following inspections and checks are recommended to ship owners and crew to ensure compliance:
- Ventilation flaps and dampers shall move freely with all parts in place.
- The crew is to be familiar with the operation of fire dampers.
- Fire dampers/ducts indicated on the Fire and Safety Plan are to be marked, indicating clearly which space the damper serves.
- Other ventilation inlet/outlet closings are preferably to be marked to the same standard as above.
- Operating handles and stoppers are to be in good working condition.
- A responsible officer is to be assigned for maintenance and inspection.
- Periodic maintenance and required tests of local and remote operation are to be carried out.
- Adequate testing procedures are to be stated in the vessel’s PMS and/or SMS.
- Open/closed positions are to be properly marked.
- The vessel-specific fire-training manual is to explain in detail the operation and use of fire and smoke dampers.
- The checking and operation of fire dampers and the main inlets and outlets of ventilating systems are to be included in regular fire drill scenarios.
Fire dampers are and will continue to be in focus, since they have a vital safety function in case of fire. It is important that the vessel’s crew execute proper maintenance procedures for fire dampers and make sure that they function properly.