Sample extraction smoke detection systems
This is used for cargo spaces only.
Main components
Smoke accumulators: also used as nozzles to release CO2. Suck air samples.
Sampling pipes: Connects accumulator to control panel
Three way valves: Connects either accumulator to control panel or connects accumulator to CO2 fire extinguishing system.
Control panel: provides continuous monitoring of samples, may have viewing chamber or smoke sensing units. If smoke is sensed, alarm is sounded. It does not indicate location of fire. That is visually assessed by crew from control panel.
System is capable of continuous operation. Sequential scanning principle may be accepted under specified conditions. System does not leak any toxic or flammable substances or fire extinguishing medium in accommodation, control station or machinery area.
The system is robust to withstand usual problems faced by ships.
The system can be tested without renewal of any component.
Alternate power supply is provided.
Sensor unit shall operate when smoke density is 6.65% obscuration per metre.
There are 2 extraction fans of sufficient capacity. 1 is used at a time. Sampling pipe inner dia is over 12 mm. Means are provided on each sampling line to monitor airflow.
The control panel allows observation of smoke in the individual sampling pipe.
Sampling pipes extract equal quantities of airflow from each accumulator.
Samplings are purged periodically with compressed air.
Control panel is tested according to regulations.
SMOKE accumulators:
At least 1 accumulator in every enclosed space. They are located overhead or as high as possible. Each services 12 m radius of area.
Smoke accumulators are connected for each enclosed compartment and not inter-connected with others. In cargo hold with tween deck, accumulators are provided for both spaces.
Sampling pipes are arranged in such a way to indicate location of fire readily. They are self drained and protected from cargo.
Visual and audible sound signals
On detection of smoke, system gives audible and visual alarm at control panel and indicating units.
The control panel is placed on either Navigation Bridge or Fire control station. If at later then indicating unit is placed on Navigation bridge.
Clear information is provided near control panel.
Power supplies are monitored. Loss of power triggers distinct visual and audible alarm on control panel. Alarms can be manually silenced.
The system automatically resets to normal operation when alarm and fault conditions are cleared.
TESTING
Instructions and spares are provided for testing and maintenance.
System is tested using a smoke generator as a smoke source. Alarm must trigger on in less than 180 sec for RO RO ship vehicle deck and 300 sec for container and cargo ships.