IMO Conventions

 

5. Translate into English.

1. Меры предотвращения  пожаров на судах обусловлены  их конструкционными, организационными  и техническими аспектами.

2.  Большое  количество пожаров на судах  связано с взрывом и воспламенением  легкого вида топлива.

3.  Пожар  в машинном отделении – это,  обычно, результат воспламенения  смазочного материала в подшипниках  главных и вспомогательных механизмах.

4.  Открытый  огонь – это искры, возникающие  в процессе сварки.

5.  Необходимо  соблюдать требования к хранению  опасных грузов.

6. Красящие  вещества должны иметь низкую  теплопроводимость, чтобы не допускать  распространение огня.

7. Необходимо, чтобы на каждом судне имелись  высокоэффективные системы пожаротушения. 

 

Lesson 5.

Fire detection methods.

 

1. Read and translate the following text.

 

Fire Patrols

These are not normally carried out on a regular basis upon most vessels but they should be conducted (1) immediately prior to, or upon sailing. A thorough inspection of the vessel being made especially in hold compartments, stores, engine and boiler rooms, etc. (2) when the vessel has been vacated by shipyard personnel whilst the vessel is in port undergoing repair. Someone may have been using oxy-acetylene burning or welding equipment on one side of a bulkhead totally unaware that the beginnings of a fire were being created on the other side of the bulkhead.

The patrol should, in addition to looking for fire, assess and correct any possible dangerous situation, e.g. loose oil or paint drums, incorrectly stored chemicals, etc.

Fire Alarm Circuits

These consist of an alarm panel, situated outside of the machinery spaces, which gives indication of the fire zone. Zone circuits, audible alarms and auxiliary power supply.

Circuits

When the contacts in a detector head close (open under normal conditions) they short the circuit and cause operation of the audible fire alarm. The lines in the circuit are continuously

monitored through 1 to 2 and 3 to 4, hence any fault which develops, e.g. damaged insulation, break in the cable, causes the system failure alarm to sound.

Power failure

In the event of failure of mains supply power, automatic auxiliary power is supplied from fully charged stand-by batteries for up to 6 hours.. Most systems operate on 24V. dc, however, for those operating at mains supply of 220V. ac an inverter converts the 24V. dc to 220V. ac.

Audible Alarms

   The fire alarm is usually an intermittent audible signal whereas fault and manual test are normally a continuous audible signal.

Fire Detector Heads

Various types are available for fitting into an alarm circuit, choice is dependent upon fire risk, position, area to be covered, volume and height of compartment, atmosphere in the space, etc. To economize and simplify, standard bases are generality used in the circuit into which different types of detectors can be fitted.

Heat Sensors

These may be fixed temperature detectors, rate of rise detectors or a combination. Rate of rise detectors do not respond and give alarm if the temperature gradually increases, e.g. moving into tropical regions or heating switched on.

Increase in temperature increases the air pressure inside the hemi-spherical bulb, if the bleed of air through the two way bleed valve from the inside of the bulb is sufficient the diaphragm will not move up and close the contacts. If however the rate of rise of temperature causes sufficient pressure inside the bulb to close the contacts, alarm will be given. In either case a bi-metal unit will at a pre-determined temperature close the contacts on to> the fixed temperature adjustment screw, giving alarm. Quartzoid bulbs of the type fitted into a sprinkler system are fixed temperature detectors used for spaces other than engine and boiler rooms.

Relevant Points

Sensitivity: The greater the heat release rate from there the poorer the ventilation and the more confined the space, the quicker will be the response of the detector and the sooner an alarm sounds.

Fixed temperature setting depends upon whether the detector is in accommodation or machinery spaces and can vary from 55°C to 70°C.

The detector is useful for dusty atmospheres as it is completely sealed but it does not give as early a warning of fire as other types of detectors. It can be tested by a portable electric hot air blower or muff.

Infra Red Flame Detector

Flame has a characteristic flicker frequency of about 25 Hz and use is made of this fact to trigger an alarm. Flickering radiation from flames reaches the detector lens/filter unit, which only allows infra-red rays to pass and be focused upon the cell. The signal from the cell goes into the selective amplifier, which is tuned to 25 Hz, then into a time delay unit (to minimize incidence of false alarms, fire has to be present for a predetermined period), trigger and alarm circuits.

Relevant Points

Very early warning of fire is possible, suitable for areas where fire risk is high, i.e. machinery spaces— but not in boiler rooms where naked flame torches are to be used for igniting oil. Reflected radiation can be a problem in boiler rooms and from running machinery. Obscuration by smoke renders it inoperative. It can be tested by means of a naked flame.

Pneumatic Type:

Increase in temperature increases the air pressure inside the hemi-spherical bulb, if the bleed of air through the two way bleed valve from the inside of the bulb is sufficient the diaphragm will not move up and close the contacts. If however the rate of rise of temperature causes sufficient pressure build up inside the bulb to close the contacts, alarm will be given. In either ease a bi-metal unit will at a pre-determined temperature close the contacts on to the fixed temperature adjustment screw, giving alarm.

 Bi-metal Coil Type:

Two bi-metal coils attached to a vertical support bracket are encased in a protective metal cap. When the temperature increases A will move to close the gap С at a faster rate than В moves to maintain the gap, this is due to В being better insulated from the heat than A. If the rate of rise of temperature is sufficient, gap С will be closed and alarm given. At a fixed temperature gap D, then gap С will be closed, giving alarm.

Quartzoid bulbs of the type fitted into a sprinkler system are fixed temperature detectors used for spaces other than engine and boiler rooms.

Photo-electric Cell Smoke Detectors

Three types are in use, those that operate by light scatter, those that operate by light obscuration and a type which combines scatter and obscuration.

A photo-cell separated by a barrier from a semi-conductor intermittently flashing light source are housed in an enclosure whose containment allows smoke but not light inside. When smoke is present in the container, light is scattered around the barrier on to the photo-cell and an alarm is triggered.

Relevant Points

Smoke may be present without much heat or any flame, hence this detector could give early warning of fire. Photo-cells and light sources are vulnerable to vibration and dirt. Testing can be done with smoke from a cigarette.

The light obscuration type is used in oil mist detectors for diesel engine crank cases and the obscuration/scatter type is to be found in the detecting cabinet of the carbon dioxide flooding system. Standard Bases

The standard bases for the various detector heads have a neon light incorporated which flashes to indicate which detector head has operated. Detector heads can be simply unplugged from the base and tested in a portable test unit which has an adjustable time delay, audible alarm and battery.

Combustion Gas Detector

Two ionization chambers connected in series contain some radioactive material which emits a continuous supply of ionizing particles.

The detecting chamber is open, the reference chamber closed and operating at a constant current since it contains air which is being ionized and the applied potential ensures that saturation point is passed. Current strength is dependent upon the applied potential, since if the potential is low not all the ionized particles reach the electrodes, some will combine with electrons and thus be neutralized.

 

Vocabulary.

Whilst – пока

Unaware – незнающий, неосторожный

A detector head –  детекторная головка

The system failure alarm – система аварийного оповещения

Audible alarm –  звуковой аварийный сигнал

The bleed of air –  продувка воздуха

Bleed valve –  выпускной клапан

A bi-metal unit –  биметаллический агрегат

To be encased in – быть упакованным, облицованным

Quartzoic bulb – кварцевая, лампа

Flicker frequency – частота мельканий

To trigger –  запускать

Detector lens –  объектив датчика

Naked flame torch – горелка с открытым пламенем

Light scatter – рассеянный свет

Obscuration затемнение

A barrier – барьер

Photo-cell – фотоэлемент

Vulnerable – уязвимый

То be unplugged from – быть вынутым из, быть отключенным от

 

 

Exercises.

1.  Answer the questions.

1.   What fire detection methods can you name?

2.   What are the tasks of fire patrols?

3.   What are fire alarm circuits consist of?

4.   When is audible fire alarm operated?

5.   What is the source of power supply in the event of failure of mains supply power?

6.   What is the choice of Fire Detector Heads dependent upon?

7.   What types of heat sensors do you know?

8.    In what condition does increase in temperature increases the air pressure inside the hemi-spherical bulb?

9.    What spaces are fixed temperature detectors used for?

10.   Under what conditions does an alarm sounds sooner ?

11.   What characteristic flicker frequency has a flame in Infra Red Flame Detector?

12.   What three types of Photo-electric Cell Smoke Detectors are in use?

13.   When is an alarm triggered in Photo-electric Cell Smoke Detector?  

14.   What test can Detector Heads be tested in?

15.   Why is current strength dependent upon the applied potential in Combustion Gas Detector?

 

2. Find the right endings of the sentences.

1. A thorough inspection by Fire Patrols of the vessel is made …

a) prior to sailing

b) while sailing

c) whilst the vessel is in port undergoing repair

 

2. An alarm panel of Fire Alarm Circuits is situated …

a) inside of the machinery spaces.

b) outside of the machinery spaces.

c) outside of the engine room.

 

3. Any fault which develops causes …

a) the system failure alarm to sound.

b) the system failure alarm to stop sounding.

c) the system failure alarm to break down.

 

4. For systems operating at mains supply of 220V ac an inverter converts …

a) the 220 V ac to 24 V ac.

b) the 24 V dc to 220 V ac

c) the 24 V ac to 220 V dc

 

5. Rate of rise detectors don’t respond and give alarm if the temperature …

a) gradually decreases.

b) doesn’t change its value.

c) gradually increases.

 

6. Alarm of rate of rise detectors will be given if …

a) the rate of rise of temperature causes sufficient pressure inside the bulb to close the contacts.

b) the rate of rise of temperature causes insufficient pressure inside the bulb to close the contacts.

c) the rate of rise of temperature causes sufficient pressure outside the bulb to close the contacts.

 

7. The detector lens/filter unit allows infra-red rays …

a) to be focused inside the cell.

b) to be focused upon the cell.

c) to be distributed inside the cell.

 

8. Obscuration by smoke can be tested by …

a) means of a naked flame.

b) means of a Flame Detector.

c) means of a Smoke Detector.

 

9. Photo-electric Cell Smoke Detectors can give early warning of fire because …

a) smoke may not be present without much heat.

b) any flame may not be present without smoke.

c) smoke may be present without much heat or any flame.

 

10. If the potential in Combustion Gas Detector is low …

a) all the ionized particles reach the electrodes.

b) not all the ionized particles reach the electrodes.

c) all the electrons reach the electrodes. 

 

3. Restore the following sentences.

1. Fire patrol should in addition to looking for fire … 2. Если скорость подъема температуры  приведет к тому, что давление  внутри лампы … 3. When the contacts in a detector head close ... 4. Стационарный термодатчик может  использоваться в запыленной  обстановке т.к. он полностью  герметичен … 5. In the event of failure of mains supply power … 6. Огонь имеет частоту мерцания  около 25 Гц … 7. The choice of fire detector heads is dependent upon … 8. Две ионизационные камеры соединенные  последовательно содержат радиоактивный  материал, который … 9. When smoke is present in the container light is scattered around the barrier … 10. Головки сигнализации могут  быть просто удалены от основы (опоры) и проверены на переносной  испытательной установке, которая  …

a) … to close the contacts? Alarm will be given. b) … пожарной опасности, положения, района действия, объема и высоты отсека и т.д. c) … emits a continuous supply of ionizing particles. d) …оценить и исправить любую потенциально опасную ситуацию. e) … but it does not give as early a warning of fire as other types of detectors. f) …вспомогательная энергия поступает из полностью заряженных резервных батарей, время действия которых рассчитано до 6 часов. g) … фотодиод (фотоэлемент) и сигнал тревоги запускается. h) … has an adjustable time delay, audible alarm and battery. i) … они закорачивают цепь и приводят к действию слышимый сигнал пожарной тревоги. j) … and use is made of this fact to trigger an alarm.

 

Home task.

1. Find the equivalents of the following word combinations.

1. Fire Patrol                               a) стравливание воздушной пробки

2. Fire alarm circuit                    b) детектор выхлопных газов

3. Detector head                          c) фотоэлектрический точечный дымовой извещатель

4. System failure alarm               d) пожарный патруль

5. Stand-by battery                      e) датчик, измеряющий уровень повышения температуры за

                                                    определенное время 

6. Heat sensor                              f) электрический вентилятор горячего воздуха           

                                                        (выдувающий наконечник)

7. Fixed temperature detector     g) элемент выдержки времени

8. Rate of rise detector                h) инфракрасный датчик пламени

9. The bleed of air                       i) сигнал о неисправности системы         

10. The electric hot air blower    j) тепловой датчик

11. Infra red flame detector        k) датчик определения темпа нарастания температуры               

12. Time delay unit                     l)  резервный аккумулятор (батарея)

13. Photo-electric cell smoke detector        m) цепь аварийной пожарной сигнализации

14. Combustion gas detector      n) детекторная (измерительная) головка

 

2.  Match the names of fire detectors with their functions.

a) Fire Patrol

b) Fire Alarm Circuit

c) Fire Detector Head

d) Rate of Rise Detector

e) Fixed Temperature Detector

f) Infra Red Flame Detector

g) Photo-electric Cell Smoke Detector

h) Standard Bases

i) Combustion Gas Detector

 

1. It’s quartzoid bulb fitted into splinker system. It is used for spaces other then engine and boiler rooms.
2. They can be fitted into any alarm circuit. Their choice is dependent upon fire risk, position, area to be covered, volume and height of compartment, atmosphere in the space, etc.
3. Flickering radiation from flames reaches the detector lens/filter unit, which only allows infra-red rays to pass and be focused upon the cell. The signal from the cell goes into the selective amplifier, then into a time delay unit, trigger and alarm circuits.
4. It should look for fire, assess and correct any possible dangerous situation.
5. They have a neon light incorporated which flashes to indicate which detector head has operated.
6. The detecting chamber is open, the reference chamber closed and operating at a constant current since it contains air which is being ionized and the applied potential ensures that saturation point is passed.
7. They do not respond and give alarm if the temperature gradually increases. Increase in temperature increases the air pressure inside the hemi-spherical bulb, if the bleed of air through the two way bleed valves from the inside of the bulb is sufficient, the diaphragm will not move up and close the contacts. In this case alarm is given.
8. It is an alarm panel which gives indication of the fire zone when the contacts in a detector head close they short the circuit and cause operation of audible fire alarm.
9. Three types of them are in use: those that operate by light scatter, those that operate by light obscuration and a type which combines scatter and obscuration.