Posted on 12/16/2002 12:54:20 PM PST by Dallas
ANKARA (Reuters) -
A man was killed and nine people were injured on Saturday when gas used to artificially ripen fruit exploded in a Turkish market, police said.
Erbil Esmer, 36, was killed while shopping for bananas at a fruit wholesaler in the northwestern city of Balikesir, a policewoman said.
"A spark caused the gas used to (ripen) bananas ... to explode," she said.
Nine people were treated in hospital for injuries from the strong explosion, she said. Several buildings and vehicles outside the market were damaged.
INTRODUCTION
1 There are about 40 Fruit Ripening Plants in the LA enforcement sector. Bananas are the most common fruit but other exotic fruit (eg kiwi fruit) are ripened by the same process.
BACKGROUND
2 Bananas imported green into the UK are ripened in specially constructed rooms by exposure to controlled atmosphere containing ethylene gas at a concentration of typically 0.l% by volume in air. Some rooms are heated by gas or electricity. The ethylene is introduced from pressurised cylinders, cartridges or a catalytic generator. If the introduction of ethylene is uncontrolled there is a risk that the ethylene may reach or exceed the Lower Explosive limit (LEL) and be ignited by unprotected electrical apparatus or gas heating systems. The LEL for ethylene is 3.1 %.
THE PROCESS
3 a. green bananas in cartons and at a fruit pulp temperature of around 11°C are loaded into the ripening room.
the room is closed, heated for 12 to 16 hours until the pulp temperature reaches 15 to 17°C. The heating is then switched off.
ethylene is discharged into the room at a concentration of around 0.1%. The room is then kept closed for 24 hours. The ethylene acts as a catalyst initiating the hormonal process of ripening.
at the end of this time the room is ventilated to clear the ethylene.
the room is then closed again and the atmosphere controlled at a temperature of 15 to 17°C for three to four days. The fruit pulp may reach a temperature of 32°C during this process and gases, including carbon dioxide, are evolved in substantial quantities.
the room is finally ventilated and the ripe fruit removed. A common way of ventilating involves opening the doors for at least 5, usually 15 minutes before entry is made. Extractor fans may also be used.
NB The amount of ethylene gas required for a ripening room is normally calculated on the free air space after the bananas have been loaded (ie if bananas take up to 35% of the room size. calculate the amount of ethylene required for remaining 65% free air space).
METHODS OF INTRODUCING ETHYLENE GAS
'Ethy-Gen' Catalytic Generators
4 A method by which a liquid concentrate 'Ethy-Gen' is decomposed in an electrically powered catalytic generator, to produce ethylene gas. The 'Ethy-Gen' concentrate is supplied in containers which produce about 12 ft3 (0.33 m3 ) of ethylene gas. The amount of liquid put in the generator depends on size of ripening room.
Ethylene Cartridges
5 Each ethylene cartridge contains approximately 51g of pure ethylene and the ethylene concentration in the room may be controlled simply and accurately by using the appropriate number of cartridges. Ethylene is released by piercing the cartridge with a tool which is supplied.
Ethylene and Ethylene/Nitrogen Cylinders
6 The explosion risk from ethylene can be eliminated by the use of a mixture of gas consisting of 5% ethylene in nitrogen. Pure ethylene and the mixture can be obtained from British Oxygen Company Limited and Air Products Limited.
Pure Ethylene Cylinders
7 Pure ethylene can be obtained in cylinders.
HAZARDS
8 The hazards arising from this process fall into two main categories:
Fire/Explosion
introduction of pure ethylene from cartridges may result in localised and short-lived flammable gas/air mixtures.
extensive flammable gas/air mixtures may result from the uncontrolled addition of ethylene from a large cylinder or from a multiple discharge of small cartridges or the use of the catalytic generator in too small a room.
where gas-fired heating equipment is used, flame failure may result in quantities of unburnt gas entering the room and creating a flammable atmosphere.
Toxic/asphyxiation
excess addition of ethylene/nitrogen mixture from cylinders;
the evolution of carbon dioxide during the ripening process;
the combustion of fuel gas toxic combustion products (chiefly CO) will be produced if there is not sufficient oxygen present at the burner for complete combustion.
9 Incidents to date show that the main hazard to arise from this process is the combustion and explosion of excess quantities of pure ethylene resulting from uncontrolled discharge from large capacity cylinders. There may be a further hazard from asphyxiating gases in the ripening room, eg carbon dioxide and nitrogen if entry is made before ventilation is complete.
Ethanol
10 Ethy-Gen concentrate Ethanol. It is a mild irritant avoid contact with skin or eyes. It can be fatal if taken internally. It is also a highly flammable liquid.
PRECAUTIONS
11 a. Flammable or asphyxiating atmospheres can be created by admitting excess ethylene gas. The use therefore of cylinders of pure ethylene should be vigorously discouraged. Enforcement officers should press for a change to ethylene cartridges or Ethy-Gen generators;
a notice showing the quantity of ethylene cartridges or Ethy-Gen concentrate required for ripening in each room given different volumes of fruit etc, be conspicuously displayed in that room. This is particularly important where there are rooms of different sizes in the same premises;
it is impossible to form a flammable concentration with air using ethylene/ nitrogen cylinders but, advice should be given on the asphyxiation hazard to ensure awareness;
the ripening room should be thoroughly ventilated between loads, preferably by mechanical means;
the introduction of ethylene into a room should be undertaken only by a competent person who understands the hazards involved;
the catalytic generator must never be used in a room less than 1,150ft3 (32.56m3 ), it must never be moved while it still contains concentrate and no other liquids apart from Ethy-Gen concentrate can be used. It is virtually impossible to create an explosive or asphyxiating atmosphere using this system.
it is also advised that any gas-fired equipment installed in ripening rooms should be fitted with suitable safeguards, in the event of flame failure, which are properly maintained.
PREVENTION OF IGNITION SOURCES
12 a. No naked lights should be allowed in the room after introduction of ethylene until thorough ventilation has taken place;
Gas-fired heating systems should be turned off before ethylene is introduced;
Where small ethylene cartridges and ethylene generators are used the dilution of gas is very rapid. It is suggested that no protection against flammable atmospheres need to be provided for electrical equipment. However, ethylene should not be discharged within 2 m of fixed electrical installations. In order to prevent layering it should not be discharged less than 1m from the floor;
STORAGE OF ETHYLENE CARTRIDGES AND ETH-GEN CONCENTRATE
13 a. Quantities stored on site should be as small as is reasonably practicable;
cartridges and Ethy-Gen concentrate must be under the control of a competent person;
quantities of cartridges may be stored indoors within a suitably ventilated area as detailed in Guidance Note CS4 "The Keeping of LPG in Cylinders and similar containers";
empty ethylene cartridges be stored as for full containers and must be carefully disposed of;
Ethy-Gen concentrate (a highly flammable liquid) may be stored in a suitable bin or cupboard indoors in quantities of up to 50 litres. Greater quantities require special storage facilities as detailed in Guidance Note CS2 "The Storage of Highly Flammable Liquids". No naked flames or smoking should be permitted in these storage areas.
ENQUIRIES
14 Any further enquiries on the content of this circular may be referred in the first instance to the Enforcement Liaison Officer at the local HSE Area Office.
Unless you like ripe bananas.
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