IMO Conventions

Performance

Range about 3 to 4 m, duration of discharge about 15 s. Body is tested to 35 bar (3.5 MN/m²). ry powder acts to smother a fire in a similar way to a blanket. Owing to the great shielding properties of the powder cloud the operator can approach quite close to the fire. The sodium bicarbonate powder will, due to the heat from the fire, produce СО₂ which should further assist in smothering the fire.

Soda-acid Portable Fire Extinguisher

Construction (Fig. 8.16)

Riveted mild steel, lead coated internally and externally, is used for the body of the extinguisher. A screwed brass neck ring is riveted to the top dome of the mild steel body and the brass head assembly, which incorporates plunger and acid bottle carrying cage, is screwed into it. The head assembly joint is either acid resisting rubber or greased leather. The nozzle is made of brass and the delivery tube with loose gauze filter, generally copper.

To ensure that the solution does not leak out of the nozzle due to increase of air pressure in the enclosed space above the solution (due to increase of temperature), a non-return vent valve is usually incorporated in the head assembly.

Contents

A 9 litre sodium bicarbonate solution fills the body to the limit of the level indicator and the glass bottle in the carrying cage contains sulphuric acid.

Operation

When the plunger is depressed the acid bottle is shattered and the acid is released. The sulphuric acid will then react with the surface of the sodium bicarbonate solution and the result of this chemical reaction is СО₂. The СО₂ builds up in pressure and the solution is then driven out of the extinguisher through the dip tube and nozzle.

Performance

Length of jet 9 m approximately, working pressure 2.7 bar to 3 bar, duration of discharge 2 minutes. Body is tested hydraulically to a pressure of 25 bar (2.5 MN/m²) approximately.

Soda-acid fire extinguishers should not be used in machinery spaces for fighting oil fires as the principal substance discharged from such extinguishers is water.

Vocabulary.

Drawn steel –  тянутая сталь

Brass pressing –  латунное прессование

Bottle - баллон

Bursting disc – предохранительная (разрывная) мембрана

Discharge horn – выпускающий рычаг

Swivel - проворачивать

Safety pin – стопорный штифт

Neck ring – кольцо горловины

Plunger – поршень, плунжер, толкатель

swivel safety guard – поворотное предохранительное устройство

Rubber washer – резиновая прокладка

Nozzle – форсунка, насадка

Piercer - пробойник

Wetting agent – увлажняющее средство

Riveted steel – клепанная сталь

Reinforced hose – армированный шланг

Magnesium stearate –  стеарат магния

Supporting bracket –  опорный башмак

Top dome – верхний купол

Greased leather –  смазанная кожа

Loose gauze filter –  рыхлый сетчатый фильтр

Non-return vent valve – невозвратный выпускной клапан

 

2. Answer the questions.

 

Portable CO2 Fire Extinguisher.

1. What is the body made?

2.  What forms the head assembly?

3.  What does the head assembly incorporate?

4.  What is the content of this type of CO2 fire extinguisher?

5. Describe its operation.

6.  What are its performance characteristics?

CO2 and Water Portable Fire Extinguisher.

1. What is body coated?
2. What is the brass neck ring soldered to?
3. What does its brass head assembly incorporate?
4. What is the purpose of small radial vent holes?
5. What is the name of the part which gives water jet or spray?
6. What serves to keep the extinguisher vented?
7. What is its content?
8. Describe its operation and performance characteristics.

Dry Powder Portable Fire Extinguisher.

1. What is the body made of?
2. What is its head assembly fitted with?
3. Where does a reinforced hose lead to?
4. What is the brass nozzle fitted with?
5. What is its content?
6. Descibe its operation and performance characteristics/
7. Why can the operator approach quite close to the fire?  

 

Soda-acid Portable Fire Extinguisher

1. What material is the body made of?
2. What does its head assembly incorporate?
3. What is the head assembly joint?
4. What is the reason of the solution leakage?
5. What part of head assembly prevents the solution leakage?
6. What is its content?
7. Describe its operation and performance characteristics.

 

3. Find the equivalent of translation.

riveted steel welded steel an injunction tube head assembly spring-loaded plunger discharge tube reinforced hose brass nozzle lever-operated control valve dip tube bursting disc swivel safety guard rubber washer

труба впрыскивания предохранительная мембрана передний (верхний) узел сварная сталь латунная насадка поворотное предохранительное устройство уровне-регулирующий клапан клепанная сталь армированный шланг труба погружения выпускная труба выпускной рычаг резиновая прокладка

 

4. Choose the right endings of each sentence.
1. The body of CO2 portable fire extinguisher is made of …
1. … riveted or welded steel.
2. … of solid drawn steel.
3. … of welded steel zinc.
4. … of riveted mild steel, lead coated internally and externally.
2. The head assembly of CO2 and water portable fire extinguisher incorporates …
1. … plunger, handle and swivel safety guard.
2. … plunger and acid bottle carrying cage.
3. … a spring-loaded plunger.
4. … a level-operated valve, copper dip tube, bursting disc.
3. The body of the dry powder portable fire extinguisher contains …
1. … 4,5 kg of dry powder.
2. … 4,5 kg of liquid CO2.
3. …  9 litre sodium bicarbonate solution
4. … 9 litre of fresh water and a wetting agent.
4. Soda-acid portable fire extinguisher operate as follows:
1. A safety pin (not shown in sketch) would first be removed and then the valve operating lever would be depressed. The liquid CO₂ would pass into the discharge horn and emerge as a cloud of C0₂.
2. When the plunger is depressed the acid bottle is shattered and the acid is released. The sulphuric acid will then react with the surface of the sodium bicarbonate solution and the result of this chemical reaction is СО₂. The СО₂ builds up in pressure and the solution is then driven out of the extinguisher through the dip tube and nozzle.
3. The hose is first uncoiled from the body and the swivel guard is swung to uncover the plunger. The plunger is then depressed, this releases the СО₂ which then drives the water out of the extinguisher via the dip tube and hose.
4. The extinguisher is removed from its supporting bracket and the safety cap is removed. When the plunger is depressed it pierces the СО₂ bottle seal, СО₂ then blows out the powder charge.
5. CO2 portable fire extinguisher has the following performance characteristics.
1. Length of jet 9 m approximately, working pressure 2.7 bar to 3 bar, duration of discharge 2 minutes. Body is tested hydraulically to a pressure of 25 bar (2.5 MN/m²) approximately.
2. Range about 3 to 4 m, duration of discharge about 15 s. Body is tested to 35 bar (3.5 MN/m²). ry powder acts to smother a fire in a similar way to a blanket.
3. Range about 3 to 4 m in still air, duration of discharge about 20 s, about 2.5 m³ of gas is produced.
4. Length of jet 10.6 m approximately, spray 6.06 m with about 36 m² of cover. Duration of discharge approximately 60 seconds. Body tested hydraulically to 25 bar (2.5 MN/m²).

 

   5. Restore the sentences.

The head assembly incorporates a lever-operated valve, copper dip tube, bursting disc and a discharge horn made of …  The liquid CO2 would pass into the discharge horn and … A brass double purpose nozzle is fitted to the delivery end of the reinforced rubber hose and … The hose is first uncoiled from the body and the swivel guard … The body of the extinguisher contains approximately … The sodium bicarbonate powder will produce СО2 which … To ensure that the solution does not leak out of the nozzle … Soda-acid fire extinguishers should not be used in machinery spaces for fighting oil fires as …

a) …is swung to uncover the plunger. b) … should further assist in smothering the fire. c) … non-conducting (electrically) material. d)… a non-return vent valve is usually incorporated in the head assembly. e) …  the principal substance discharged from such extinguishers is water. f) … emerge as a cloud of C02. g) … 4.5 kg of dry powder. h) … the nozzle can be operated to give water jet or spray as desired.

6.  Translate into English.

1. Огнетушитель ОП-9

Найбольший  среди переносных порошковых огнетушителей  с массой заряда 9кг. предназначен для  тушения возгорания твердых, жидких и газообразных веществ (класса А, В, С), а также возможно их применение для тушения электроустановок, находящихся  под напряжением до 1000 В. Не следует  использовать порошковые огнетушители для тушения оборудования, которое может выйти из строя при попадании порошка (ЭВМ, электронное оборудование, электромашины коллекторного типа и т.д.).

2. Огнетушитель  ОУ 5 (ВВК3,5)

Огнетушитель  СО2 (углекислотный) переносной вместимостью баллона 5 литров(3,5 килограмма), предназначен для тушения загорании различных веществ, горение которых не может происходить без доступа воздуха. Преимуществом углекислотных огнетушителей является отсутствие следов тушения т.к. углекислота после использования не оставляет следов и грязи.

3. Предназначены для тушения пожаров  огнетушащими пенами: химической  или воздушно-механической. Химическую  пену получают из водных растворов  кислот и щелочей, воздушно-механическую  образуют из водных растворов  и пенообразователей потоками  рабочего газа: воздуха, азота  или углекислого газа.

4. Тушить пеной загоревшиеся электрические установки и электросети, находящиеся под напряжением, нельзя, так как она является проводником электрического тока.

5. К недостаткам пенных огнетушителей  относится узкий температурный  диапазон применения (5—45 °C), высокая коррозийная активность заряда, возможность повреждения объекта тушения, необходимость ежегодной перезарядки.

 

7. Discuss the following topic.

Достоинства и недостатки разных видов огнетушителей.

 

Lesson 7.

1. Read and translate the text.

 

C0₂ FLOODING SYSTEMS

 

This system of smoke detection, alarm and CO₂ flooding is frequently used for hold spaces and in some instances may be found as additional fire fighting equipment for engine rooms.

For the detection of smoke, 20 mm diameter sampling pipes are led from the various hold compartments in the vessel to a cabinet on the bridge. Air is drawn continuously through these pipes to the cabinet by suction fans, which deliver the air through a diverting valve into the wheel house.

When a fire breaks out in a compartment, smoke issues from the diverting valve into the wheelhouse, warning bridge personnel of the outbreak. Simultaneously, an electronic smoke detector in the cabinet sets off audible alarms, hence if the bridge is unoccupied (e.g. in port) the notice of outbreak of fire is still obtained.

With the cabinet is a dark chamber wherein the sampling pipes terminate in labelled chimneys. Diffused light illuminates strongly any smoke issuing from a chimney, hence the compartment which is affected by fire can easily be identified. Below the dark chamber in the cabinet is a well lighted compartment fitted with a glass window and hinged flap cover. Inside this compartment, 13 mm diameter glass tubes are fitted which are the ends of the sampling pipes, these glass tubes protrude into the metal chimneys in the dark chamber above. Small nylon propellers are visible inside the glass tubes in the lighted portion of the cabinet and when the fans are in operation these propellers will be seen to be continuously whirling if the sampling tube is not blocked.

Change over valves are generally situated inside the lower portion of the cabinet, one for each of the sampling pipes. To flood an affected compartment with CO₂ gas, the operator would first operate the appropriate change over valve and secondly release the requisite number of CO₂ cylinders for the compartment. CO₂ gas would then pass through the sampling pipe to the space in which the fire exists.

When a smoke detection system is to be used for the hold compartments of a refrigerated cargo vessel the lines to the refrigerated holds will be blanked-off in the detector cabinet. These blanks can be removed once per watch as a test (for a few days after loading cargo) and removed altogether when the hold is open and defrosted.

Note:

When an outbreak of fire in a compartment is detected, the fire may be of small proportions and be capable of being extinguished by means other than flooding with the СО₂ equipment provided. In this event it would be necessary for personnel to enter the compartment in order to extinguish the fire. However, after inspection, the fire may be such that C0₂ flooding is necessary. Before this is done, an audible alarm should first be operated warning personnel that C0₂ flooding of the compartment is about to be used.

After the fire has been extinguished, the compartment must be well ventilated before entry for damage inspection, as СО₂ gas is heavier than air and does not support human life.

CO2 Total Flooding System for Machinery Spaces

For machinery spaces containing diesel propelling machinery, or auxiliary machinery whose total power is 746 kW or more a fixed Fire-fighting installation has to be provided. One such system is the СО₂ total flooding system which must give a 40% saturation of the compartment, of which at least must be discharged into the compartment in about two minutes.

СО₂ flooding is often used for tanker engine rooms and pump rooms even if the machinery used is steam turbine.

Operation

First ensure that the compartment is evacuated of personnel and sealed off. This necessitates closing all doors to the engine

room, shutting down skylights, closing dampers on vents and stopping ventilation - Pumps should also be stopped and collapsible bridge valves closed. In a modern vessel the sealing off can be done by remote control from the fire control station generally using a compressed air or hydraulic system.

The door of the steel control box situated at the fire control station would then be opened, this operates a switch which may have a dual purpose. One is to operate audible and visual alarms in the engine room spaces, the other may be to shut ventilation fans. The СО₂ direction valve handle- would then be pulled and this would be followed by gas release.

Maintenance and Testing

Ensure that all moving parts are kept clean, free and well

lubricated. Wires must be checked for tightness, toggles and pulleys must be greased. With the use of compressed air the СО₂ distribution pipes could be blown through periodically. СО₂ bottles must be weighed regularly to check contents (an ultrasonic or radioactive isotope unit detector could be used to check liquid level).

Note:

The CO₂ storage bottles have seals which also act as bursting discs, should there be а СО₂ leakage from one or more of the starting bottles this cannot result in СО₂ discharge into the engine room from the battery because of the cable-operated safety valve. When leakage occurs either in the starting section or main battery a pressure switch in the lines will cause alarms to be sounded, vents to atmosphere can then be opened.

Bulk Carbon Dioxide System

This system was designed to replace the flooding systems for machinery and hold spaces which use a considerable number of carbon dioxide bottles.

It consists of a large, well insulated container (older systems may have two containers) which holds carbon dioxide at a working pressure of about 21 bar, temperature about - 20°С. In order to maintain this low temperature, duplicated refrigeration units automatically controlled by the pressure of the carbon dioxide are used. One refrigeration unit would and in the event of failure, the other would cut in automatically and warning would be given.