1. FIRE & SAFETY FIRE DETECTION SYSTEM

2. WHEN VESSEL OPERATED WITH UMS CONDITION, FIRE DETECTION SYSTEM MUST BE INSTALLED TO REPLACE FIRE PATROL FUNCTION (WATCHKEEPER) REQUIRED BY ALL MAJOR CLASSIFICATION SOCIETIES & NATIONAL AUTHORITIES FOR UMS VESSEL.

3. TYPE OF DETECTOR HEAD

4. 1.IONIZATION CHAMBER 2.SCATTER SMOKE DETECTOR 3.OBSCURATION SMOKE DETECTOR 4.RATE OF RISE DETECTOR 5.FIXED TEMPERATURE DETECTOR 6.INFRA RED FLAME DETECTOR 7.UV FLAME DETECTOR

5. IONIZATION CHAMBER

6. Gap A open to atmosphere (ionization chamber) Gap B enclosed (reference chamber) Radioactive source + ve - ve COMBUSTION PRODUCT DETECTOR

7. IONIZATION CHAMBER The detector chamber is open, reference chamber is closed. The presence of radioactive source introduces free ions in the gaps permitting leakage current to pass where gaps considered as very high resistors having values depending on the amount of radiation present and voltage applied. Negative ions slowed down when attached to burn particles altering the voltage across the potential divider and the trigger circuit operates

8. SCATTER SMOKE DETECTOR

9. Photo cell Light barrier Light source Shadow area Air and smoke diffuses through baffles SCATTER SMOKE DETECTOR

10. These detectors make use of the Tyndall effect as shown It will seen that a light radiating from the lamp to be scattered pass the light barrier illuminating the photocell and alarm operates. The small voltage generated in the photocell is amplified to actuate the alarm SCATTER SMOKE DETECTOR

11. OBSCURATION SMOKE DETECTOR

12. Smoke enter light path through aperture 30 cm long mounting tube photocell Light source Lens

13. OBSCURATION SMOKE DETECTOR Smoke obscures the light from the lamp, reduces the current through the photocell and cause the alarm to sound Semiconductor light sources have been introduced to overcome difficulties with filament lamps The sensitivity of light is defined in % light obscuration per metre.

14. RATE OF RISE DETECTOR

16. Supporting bracket Bimetallic strip A Bimetallic strip B Thin metal cup Operating principle RATE OF RISE HEAT DETECTORS Thick metal cup

17. RATE OF RISE HEAT DETECTOR Utilizing a pair of bimetallic strips to sense the temperature. Strip A has high thermal inertia due to enclosed in insulating material. Strip B surround by thin metal cap – have a faster response. Increase in temperature causes the bimetallic strips to bend to the right. Gap G will close, operating the alarm when temp rise too rapid.

18. RATE OF RISE HEAT DETECTOR Fixed temperature feature incorporated to ensure that slow burning fires will eventually be detected. This formed a stop for strip A which allow strip B to close gap G at predetermined temp.

19. FIXED TEMPERATURE DETECTORS

20. FIXED AIR TEMPERATURE HEAT DETECTORS These trigger the alarm when the air temperature reaches a predetermined level, usually 70 o C for machinery space. The most commonly available sensors are bimetallic devices and low melting point solder links which release when heated Other are Thermistors and liquid filled glass bulb which burst at predetermined temperature

21. INFRA RED FLAME DETECTORS

22. INFRA RED FLAME DETECTOR

23. This type of detector comprises a silicon solar cell fitted with a dark lens or filter which focuses radiation from a wide angle The material in the lens or filter attenuates low frequency heat radiation from hot parts of machinery and light emitted by engine room illumination to minimized false alarms. In additional the signal from the solar cell is processed by a selective amplifier which has a maximum gain at 25 Hz. It has been found that flame has a characteristic flicker around this value due to turbulence.

24. INFRA RED FLAME DETECTOR Trigger circuit incorporate a delay and release an alarm only for a predetermined period Any heat and light sources or even sudden flare up may likely due to high pressure oil leakage is ignited, the solar cell operative to energy from a fire

25. UV FLAME DETECTOR

27. ULTRA VIOLET FLAME DETECTOR Ultra violet radiation from fire Quartz window Gas fillet glass envelope Special coated wire electrode

28. UV FLAME DETECTOR It use a pair of electrodes enclosed in a gas filled envelope. Voltage pulse are applied across the electrodes at a level just below the electrical breakdown value. When the ultra violet radiation from the flame of a fire strike the special coating on the electrodes, electrons are release thus reducing the breakdown of electrodes while the applied voltage pulse is present. When fire exists, each voltage will cause discharge, allow a current pulse to flow thru the alarm trigger circuit.

29. !!!!!!!!!!!!!!!!!!!!! ALL TYPE OF DETECTORS HAVE OWN WEAKNESS. TO OVERCOME THESE WEAKNESS, IN A COMPREHENSIVE FIRE DETECTION SYSTEM, COMBINATION OF 3 TYPES OF DETECTORS ARE EMPLOYED INSTEAD OF 1 TYPE ONLY.

30. WEAKNESS & DISADVANTAGES

31. IONIZATION CHAMBER IT DOES NOT DEPEND ON THE COMBUSTION PRODUCTS BEING VISIBLE, IT IS THE NUMBER OF PARTICLES THAT IS IMPORTANT. EASILY TO DETECT THE FALSE ALARM IF SENSITIVITY SETTING IS TOO HIGH. DOES NOT REACT WHEN COMBUSTION PRODUCTS IS ORIGINATED FROM ALCOHOL & ACETONE.

32. SCATTER SMOKE DETECTOR LAMP FAILURE LEAD THE DETECTOR INOPERATIVE. MOST LAMPS ARE VULNERABLE TO VIBRATION & HAVE UNPREDICTED LIFE. PHOTOCELLS ARE VULNERABLE TO VIBRATION & CONTAMINATION.

33. OBSCURATION SMOKE DETECTOR FAILURE OF LAMP CAUSE ALARM TO INITIATED. SENSITIVITY REDUCED WHEN TUNGSTEN FILAMENT SAGGING WITH AGE, CAUSING DEFOCUSING OF THE LIGHT BEAM. PARTICLE SIZES & SMOKE COLOUR CAN EFFECT THE RESULT.

34. RATE OF RISE DOES NOT RESPOND OR LESS SENSITIVE TO SLOW INCREASES IN AIR TEMP.

35. INFRA RED DETECTOR EASILY INITIATED BY FALSE ALARM. –REFLECTION OF RADIATED ENERGY FROM VIBRATING & ROTATING MACHINERY PARTS. SURROUNDING HEAT & LIGHT SOURCE CAN SWAMP THE SOLAR CELL. COST LIMITS ITS WIDESPREAD USE. UNABLE TO DETECT FIRE IF SCREEN BY SMOKE.

36. UV DETECTOR MORE OR LESS SAME WITH INFRA RED DETECTOR. WIDELY USED AT SHORE BASED BUT NOT COMMON USED ON SHIP. SENSITIVITY IS LOWER THAN INFRA RED DETECTOR.

37. HOW TO TEST THESE DETECTOR??

38. 1.IONIZATION CHAMBER BY INJECTING BUTANE GAS (AEROSOL FORM). THE LONG CHAINS OF BUTANE’S MOLECULAR CORRESPOND IN SIZE TO THE COMBUSTION PRODUCTS OF FIRE. 2.SMOKE DETECTOR BY CIGARETTE SMOKE OR BURNING RAG. 3.RATE OF RISE DETECTOR BY USING SMALL ELECTRIC HEATED MUFF. BY MEANS OF PORTABLE HAIR DRYER. 4.FLAME DETECTOR BY MEANS OF CIGARETTE LIGHTER OR TORCH LIGHT.

39. POINTS TO CONSIDER WHEN POSITIONING THE DETECTORS

40. PRESENT OF BEAM GIRDER & WEB IN ER STRUCTURE CAN BLOCKED THE VIEW OF DETECTORS – ACTION DELAY & COULD LEAD TO SERIOUS CASE. STRONG CURRENT OF AIR FLOW, DISPERSE SMOKE & PARTICLES AWAY FROM DETECTORS. SENSITIVE & EASILY DAMAGED TO VIBRATION. HEIGHT PROBLEM – SENSITIVITY AFFECTED. STRONG LIGHT SOURCE COULD IMPAIR THE PERFORMANCE. SHOULD NOT LOCATED AT AREA WHERE SPURIOUS FALSE ALARM CAN EASILY INITIATED.

41. REMOTE FIRE DETECTOR??

42. THOSE DETECTORS WHICH LOCATED REMOTE FROM CARGO HOLD (USUALLY IN BRIDGE) AND ONLY THE SAMPLING PIPE FOUND IN CARGO HOLD :- –POSSIBLE DAMAGE TO DETECTOR DUE TO LOADING OF CARGO, VEHICLE ETC. –DUST, DIRT & OTHER PARTICLE MAY DAMAGE THE DETECTOR. –FAULTY DETECTOR’S WIRING IN CARGO HOLD COULD RESULT SERIOUS FIRE OUTBREAK. –SAMPLING LINE FOR FIRE DETECTOR CAN BE USED FOR EXTINGUISHING PURPOSES, THUS SAVING IN COST.

43. CONTROL PANEL AUDIBLE FIRE ALARM CIRCUITS FIRE ZONE IDENTIFICATION. AUTOMATIC CHANGE OVER POWER SUPPLY. SYSTEM FAULT ALARM CIRCUITS.

44. AUDIBLE FIRE ALARM CIRCUITS RELAY OPERATED FROM ZONE IDENTIFICATION CCTS. GIVE AUDIBLE SIGNAL WHEN OPERATED BY FIRE DETECTOR & CONTINUOUS UNTIL SET OFF BY MANUALLY SWITCH. SILENCING THE ALARM CARRIED OUT BY RESET SWITCH, ONLY BY RESPONSIBLE OFFICER. LOCATING OUTSIDE ER – ALLEYWAY OF ENGR CABIN IS THE BEST. WHY NOT INSIDE THE BRIDGE??

45. FIRE ZONE IDENTIFICATION GROUPS OF DETECTOR ARRANGED IN CCT ACCORDING TO THEIR LOCATION. ALARM INDICATING LIGHT CORRESPONDENCE TO FIRE ZONE. ZONE IS FAIRLY WIDE RANGING. WHERE POSSIBLE, PURIFIER, GENERATOR, STORE & W/SHOP ROOM SHALL HAVE A SEPARATE ZONE.

46. AUTOMATIC CHANGE OVER MAJORITY SYSTEM 24V DC, CONNECTED WITH STANDBY BATTS. NORMAL STATE – BATTS FULLY CHARGED BY POWER SUPPLY. AUTO C/O TO BATTS POWER BY MEANS OF INVERTER. BATTS POWER CAPACITY – 6 HRS FOR NO ALARM STATE & 1/2 HOUR FOR ALARM SOUNDING.

47. SYSTEM FAULT ALARM CCT SELF CHECKING CCT. POWER SUPPLY FAULTS. LOOP & LINE TERMINATION MONITORING EARTH LEAKAGE MONITORING

48. COMMON CHECKS & INSPECTION AUDIBLE FIRE ALARM & ZONE INDICATING LIGHT IS WORKING PROPERLY. EXTENSIVE SIMULATION TEST FOR DETECTORS. AUDIBLE ALARM INDICATING LIGHT FOR SYSTEM FAILURE IS WORKING INCLUDING CCT BREAK & EARTH LEAKAGE MONITORING. EMERGENCY BATTS SUCCESSFULLY CUT IN WHEN POWER LOSS OCCUR.

49. CONCLUSION WIDE SELECTION OF DETECTORS AVAILABLE BUT NEED TO EMPHASIZE ON ADVANTAGE & DEMERIT. SELECTING RIGHT & GOOD COMBINATION OF DETECTORS TOGETHER WITH THOROUGHLY & SYSTEMATIC TESTING COULD OFFER ADEQUATE PROTECTION & DETECTION WITHOUT SPURIOUS FALSE ALARMS. ……AND…PEACEFUL SLEEP AT NIGHT.