the bhopal disaster: how it happened - drum storage

by:Demi     2019-09-11
the bhopal disaster: how it happened  -  drum storage
Stewart Diamond Zhan
1985 this is a digital version of an article from The Times Print Archive, before it starts online in 1996.
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According to current and former employees, the Bhopal gas leak resulted in at least 2,000 deaths due to operational errors, design defects, maintenance failures, training defects and economic measures endangering safety, technical documents of the company and chief scientist of the Indian government.
These are one of the seven discoveries.
The New York Times reporter began a week-long survey after December.
A toxic methyl isocyanate gas leak from a joint Carbide plant in the central Indian city of Bhopal has caused the worst industrial disaster in history, shocking India and the world.
The questions raised by this tragedy include how it happened and who should be responsible for it.
The survey involved more than 100 interviews conducted in Bhopal, New Delhi, Mumbai, New York, Washington, and Danbury, Connecticut.
And Research Institute, W. Va.
It found information that could not even be obtained by United Carbide, the main owner of the plant where the leak occurred, because the Indian authorities refused to obtain some documents, equipment and personnel from the company's representative.
The Times investigation provides evidence of at least 10 violations of the standard procedures of the parent company and its Indian companiesrun subsidiary.
Advertising Director of United Carbide India Ltd.
The operators of the factory were reluctant to address the issue of responsibility for the tragedy in which about 200,000 people were injured.
The manager of the factory refused to discuss the violation.
The general manager of the Indian company refused to talk about the details of the accident or the conditions under which the accident occurred, although he did say that the implementation of the safety regulations was the responsibility of the Bhopal factory executives.
In recent days, when asked about the shortcomings disclosed by The Times in the investigation, a spokesman for the headquarters of Danbury United carbide said that any suggestion about the cause of the accident was speculation, and stressed that the joint carbide will not "contribute" to this speculation ". (
The article describing the company's relationship with its Indian subsidiary and its comments on the Bhopal accident appears on page 7. )
Summary of The Times's review of some company documents and interviews with chemical experts, factory workers, company officials and former officials disclosed these and other irregularities in Bhopal :-
When an employee finds an initial leak of isocyanate at 11: 30M. on Dec.
2, supervisor-
He later said he believed it was leaking
Several workers said they decided to deal with the matter only after the next tea break.
For the next hour or more, the reaction that occurred in the tank was out of control.
"The internal leak has never bothered us," one employee said . ".
In fact, workers say there is little investigation into the cause of the leak.
They said the issues were either addressed without further inspection or ignored. -
The factory staff said that a few months before the accident, the management turned off a refrigeration unit designed to keep isocyanate salt cool and inhibit chemical reactions.
The shutdown violated the procedures of the factory. -
According to several employees, about two hours after the leak began, a worker who trained not to meet the factory's original standards was ordered by a novice supervisor to clean a pipe that was not properly sealed.
This procedure is prohibited by plant rules.
Workers believe that the most likely source of pollution to trigger an accident response is water in the process. -
Technical experts say these three major safety systems, at least two of which were built according to the specifications of the joint carbide plant at the W InstituteVa.
Unable to cope with the conditions that existed on the night of the accident.
Also, one of the systems has been running for several days and the other has been out of maintenance for several weeks. -
Factory operators failed to transfer some of the isocyanate salts from the problem tank to the standby tank as required, as they said the spare tank was not as empty as it should be.
Workers say it is a common practice to leave isocyanate in a spare tank, although the standard procedure requires it to be empty. Advertisement-
According to isocyanate il Qureshi, who was on duty at the time of the accident, the plant's instruments were unreliable.
For this reason, he said, he ignored the initial warning of the accident, and one instrument showed that one of the three methyl salt tanks had increased pressure five times in an hour. -
Employees say there are no other operations at the Bhopal plant (including the West Virginia plant) that are used to monitor its functions and quickly alert employees to leaked computer systems.
They added that the management relied on the worker to perceive the leaking methyl isocyanate when the eye began to water.
This practice violates the specific order in the technical manual of the parent company entitled "Isocyanate Ester", which sets out the basic policies for the manufacture, storage and transportation of chemicals.
"Although the tear gas effect of steam is very unpleasant, this feature cannot be used as a means of reminding people," the manual said. ''-
According to about a dozen factory employees, the requirements for training levels, for experience, education and maintenance levels have been significantly reduced, and they say the cuts are the result, at least in part, budget cuts.
They said production cuts led them to believe the safety of the plant was threatened. -
According to several employees, employees at the isocyanate salt plant, which has little automation equipment, have been cut from 12 shift operators to 6 in 1983.
Kamal K said the plant "cannot operate safely with six people ".
Pareek is a chemical engineer who started working at the Bhopal plant in 1971 and served as a senior project engineer during the construction of isocyanate salt facility there eight years ago. -
The public did not have an effective warning of the disaster.
According to employees, the alarm issued on the night of the accident is similar or identical to the alarm issued for various purposes, including practice drills, usually about 20 times a week.
Local officials said there was no distribution of brochures or other materials around the factory to warn about the dangers it posed, and there was no public education program on what to do in an emergency. -
According to many employees, most workers panicked during the gas leak, fled to save their lives, and ignored buses that were idle on the factory floor, ready to evacuate nearby residents.
The parent company Danbury headquarters said last month: "United carbide regards safety as a top priority.
We have taken significant steps to ensure that the factories of our affiliates, as well as our own, are equipped with appropriate safeguards and that the staff are properly trained.
"Over the weekend, in response to the Times question, a company spokesman said the manager of the Indian subsidiary was" well qualified "and quoted their" excellent record ", he added that due to possible litigation in India, judicial and ethical rules and practices prevented them from answering questions.
The spokesman said: "The responsibility for plant maintenance, hiring and training of employees, establishing training levels and determining appropriate staffing levels lies in plant management. ''V. P.
Gokhale, chief operating officer, India United carbide Co. , Ltd.
This is his first detailed interview since December.
3, will not comment on the specific violations or the cause of the accident, but he said that the Bhopal plant is responsible for its own safety and there is no review from outside experts.
The Indian company has a security officer at its headquarters in Mumbai.
But the official is mainly responsible for updating the safety manual used by the company's factories, gokarai said.
Despite the autonomy of the Bhopal plant on safety issues, it was inspected in 1982 by experts from the US parent company who submitted an important report.
However, in the interview,
Gokarai believes that many of the issues mentioned in the annual report of 1982 have been corrected.
There are no signs of any problems, he said.
"We have no reason to believe that there is any reason for such an accident. ''Mr.
Gokhale, who became general manager of United Carbide India in December 1983 and has worked in the company for 25 years, added: "it is impossible for me to personally supervise 14 factories and 28 sales branches across the country and 9,000 employees in a week --to-week basis.
"In a month or two, there may be a dozen points.
In an hour's interview, he read his answer in a tape recorder saying he would tell the parent company's Danbury headquarters what he said.
He also noted down some of his comments and said that he would send them to Danbury for approval by United calcium carbide counsel.
The relationship between the company and the exact relationship between calcium carbide's US headquarters and its Indian subsidiaries is a theme
Officials from gokarai and other companies declined to discuss in detail.
But the understanding of this relationship is a key factor in determining the responsibility for the Bhopal disaster.
Lawyers from the United States and India say this is at the heart of a lawsuit filed by residents of Bhopal over damage to the accident.
Although the current situation is not clear, some evidence of the relationship between Indian and American companies has begun to emerge.
S. companies have direct representation on the board of corporate directors in India. J. M.
Mr. Rayfield, executive vice president of Danbury, is also on the board.
Four delegates from gokarai and United carbide East both acknowledged this
A department headquartered in Hong Kong. Mr.
Gokarai said the board reviewed the report on the operation of Indian subsidiaries.
In addition, it is reported that some key security decisions affecting Bhopal have been made or reviewed at the company headquarters in Danbury.
Srinivaradarajan, chief scientist of the Indian government, said that the management of the Bhopal plant told his employees that the refrigeration unit was designed to cool the isocyanate salt, and he said that the place was small and never worked satisfactorily, because the manager concluded after a discussion with US headquarters that the equipment was unnecessary.
Thomas Falia, spokesman for Danbury's headquarters, said: "As far as we know, Union Carbide has not discussed with anyone the issue of shutting down the refrigeration unit.
According to a former senior official in Bhopal, the isocyanate Ester operating manual that Bhopal is using is adapted by five Indian engineers based on similar documents prepared for the West Virginia plant: maintain a continuous cycle of the contents of the tank through a refrigeration device.
A senior official at India's United Carbide Company said that if someone died in December, almost no one would die.
If the unit is running all the time, because it will slow down the chemical reaction that occurred during the accident and increase the warning time from two hours to two days.
The worker said, when 30-
The ton refrigeration unit was shut down, saving power, and Freon in the cooling unit coil was pumped out for use elsewhere in the plant. Mr.
Gokarai specifically refused to answer questions about the refrigeration unit.
Employees criticized many of the employees who advertised more about the Bhopal factory, which used to be a display factory, but faced a continuing sales deficit since 1982, it loses a lot of trained staff its morale and attention to the details of ensuring safe operation.
The entire industrial culture of Bhopal's Union Carbide is losing.
Pareek, former project engineer.
The factory is losing money, and the top management thinks it is more important to save money than to be safe.
Maintenance practices get bad and things usually get sloppy.
There seems to be no future in the factory, and many skilled people become frustrated and leave as a result. ''Mr.
Pareek said that he resigned in December 1983 because he was frustrated with the development of the plant and because he got a better job at Goodyear India Ltd.
As production manager of department. Mr.
The cost of the company is called
Spending cuts are only made to reduce avoidable and wasteful spending.
A Danbury spokesman said that United Electric stone is carrying out an operation improvement plan, which includes a regular review of the cost reduction method.
India United carbide is involved in these projects, he said, but we do not know the details of these projects at the Bhopal plant.
The spokesman added: "The financial information provided to us indicates that the Bhopal plant is not profitable.
"In the absence of an official company account, the details of the accident and its causes have been provided by technical experts such as doctors
Mr. Varada Rajan and
Pareek and more than 30 factory workers, past and present company officials and others who know directly about factory operations.
Many of them only agree to be interviewed without revealing their identity.
Most workers barely understand English and speak in Hindi through translation.
They provided some documents, but often relied on their memories as the Indian authorities investigating the accident seized many factory files and even public records.
Almost all of the people interviewed believe that the company is not technically and managed to prepare for the accident.
1982 of the inspection reports seem to support this view, saying that the safety issue at the Bhopal plant represents "a higher probability of a serious accident or more serious consequence if an accident occurs ".
"The report strongly recommends, among other things, the installation of a larger system to supplement or replace one of the main safety devices of the plant, a water jet designed to prevent chemical leakage.
The factory staff said the change had never happened, and so had it in December.
The spray is not high enough to reach the escaping gas.
A Danbury spokesman said the company was informed that India United carbide had taken "all actions it considers necessary to respond effectively" to the 1982 report ".
Another safety device, a gas washer or neutralizer, is said to be one of the systems built according to the specifications used by the West Virginia plant because it has a maximum design pressure so it cannot cope with the accident
According to factory documents and employees, the quarter of the gas leak.
The third safety system, a torch tower that should burn the leaking gas, said that, in theory, without this pressure, the volume of the leaking gas will be able to handle it for about a quarter. Pareek.
He said the pressure is high enough to burst a tank that must flow through it before it is delivered to the torch tower.
The tower is the second system described by technical experts that meets the use specifications of West Virginia.
In any case, the pressure limit of the torch tower does not matter because it does not operate at the time of the accident.
Design Guidelines for former executives at the Bhopal plant say the parent company provides guidelines for the design of the scrubber, Torch Tower and spray system.
But he said that the detailed design work of these systems and the entire plant was done by Humphries and the Glasgow consultant Pvt. Ltd.
Subsidiaries of Mumbai, Humphries and Glasgow Limited
A London-based consulting firm
The London company is also owned by Enserch in Dallas.
A spokesman for Danbury said that United carbide provided its Indian subsidiary with "a process design package containing the necessary and sufficient information for the subsidiary to arrange the design and construction of the plant and its equipment ".
The spokesman said the company had only incomplete information about the scrubber, lighting tower and other equipment, and he declined to comment on the possible relationship between the equipment and the accident.
It is not clear whether the limitations of the safety system are caused by the guidelines provided by United carbide or the detailed design.
The employees of the factory recalled the accident on the evening of December after the accident.
They don't realize how high the pressure is in the system.
Suman Dey, a senior operator on duty, said he was in the control room at about 11. M.
It is noted that the pressure gauge of a tank reads 10 pounds per square inch, about five times the normal pressure gauge.
He said he never thought about anything. Mr.
Qureshi, an organic chemist who worked as isocyanate salt supervisor for two years at the plant, had the same reaction half an hour later.
These readings may be inaccurate, he thought.
"There has been a problem with the instrument," he later said . ".
Instruments often do not work.
"Leak was found, but tea was the first time around 11: 30. M.
Isocyanate structural workers from about 100 feet m in the control room detected a leak.
Their eyes began to water. V. N.
Operator Singh found a drop of liquid about 50 feet from the ground and some yellow
White gas in the same area.
He said, he went to the control room at about 11: 45 and told the gentleman.
Isocyanate salt leaked Qureshi. He quoted Mr.
Qureshi responded that he would see a leak after drinking tea. Mr.
Qureshi argued in an interview that he was told the leak was not the leak of isocyanate.
Until about 12: 40 after the tea was over, no one investigated the leak. M.
According to the staff on duty.
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According to the doctor, this inattention will only aggravate the already dangerous situation.
Varada Rajan, a government scientist.
AdvertisementHe is a 56-year-
Old organic and biochemist, with a PhD from Cambridge and Delhi University, is a guest lecturer in biochemistry at the Massachusetts Institute of Technology.
He is the head of the Scientific and Industrial Research Committee of the government's central research organization, which operates 42 national laboratories.
Within two weeks of the accident
Varadarajan said that he and a staff member of the Research Committee asked the plant manager of Bhopal about the experiments conducted by the plant researchers and analyzed the results of these tests
He said that some experiments were carried out on isocyanate salt at the Bhopal factory after the accident, and some experiments were made to measure the reliability of the test procedures used by the factory. Dr.
Varadarajan said in a long interview that routine testing at the Bhopal plant used a wrong approach, so the substance may have more
For example, he said that the staff of Bhopal did not adequately measure the incidence of isocyanate salts or the possible effects of cl-ions, which are highly reactive in the presence of a small amount of water.
Chlorine, in which chlorine is an ion for the production of isocyanate. Dr.
Varadarajan believes that the test procedure used by Bhopal assumes that all chloride ions present are the result of photogas decomposition, so the test measures photogas, not chloride.
Light gas is used to produce isocyanate, some of which remain in the compound to inhibit certain chemical reactions.
When his staff secretly added chloride ions to the isocyanate salt to be tested by the factory staff, Dr.
Varadarajan said that the test concluded that 23% of chlorine is light gas.
"So far," the scientist said, "the combined carbide has not yet been able to provide a clear way to distinguish light gas from chlorine methane . "
A spokesman for United Carbide Company in Danbury said: "Routine testing"
It is usually made to contain substances, including chloride ions in tanks.
"Dr. advertising
Varadarajan said that after United carbide failed to provide any cause of the accident, his staff had made their own assumptions about the cause of the accident, even as required.
A spokesman for Danbury said that a group of "very qualified" chemists and engineers from United carbide had studied the accident for 7 weeks, but still could not determine the cause.
He added: "Anyone trying to state the cause of the accident is just guessing unless he has more facts than we do and has done more analysis, testing and experiments than we do
Anyone speculating on the cause of the accident should clearly label it as a guess. ''Dr.
The analysis by Varadarajan, as well as the hard alloy documents within the Union and the dialogue with the workers, provided indirect evidence for at least one explanation that triggered the accident.
According to factory staff, 45 metric tons of leaked storage tanks, about 13,000 gallons of isocyanate.
This means that the tank is already 87% full.
A spokesman for United carbide in Danbury said the tank contained only 11,000 gallons of chemicals, well below the recommended maximum working capacity of 15,000 gallonsgallon tank.
However, even at a lower level
Capacity of 73%
Exceeding the limits set out in the Bhopal operation manual, the manual said: "Do not fill the MIC tank to a level of more than 60%.
'Mic is the abbreviation of isocyanate.
The technical manual of the parent company shows a lower limit of 50%.
According to the technical experts previously employed by the plant, the reason for the restriction is that if the reaction pressure in the tank is high, the rising speed will be reduced, allow more time to take corrective action before a toxic gas can leak.
For 13,000 gallons of chemicals, the amount reported by the factory staff to react with water, at least 1 gallon.
According to the joint carbide technical experts, 5 tons or 420 gallons of water are needed.
But the experts said the analysis of the contents of the tank did not reveal the water
Soluble urea, that is, double shrinking urine, is a normal product of the reaction between water and isocyanate.
In addition, all those interviewed agreed that it was not possible for 420 gallons of water to enter the tank.
These observations lead to assumptions about the cause.
Varadarajan and his staff suggested that there might be another reaction: water and light.
Light gas was used as a chemical weapon during World War I, and since water selectively reacts first with light gas, light gas inhibits the reaction between water and isocyanate. But Dr.
Varadarajan said his research found water
The photo-gas reaction produces something that is not suggested in the technical manual of the combined Carbide: highly corrosive cl-ion, which can react with the stainless steel wall of the storage tank, releasing metal corrosion productschiefly iron -
And a lot of heat.
Heat, the effect of chloride ions on isocyanate salts (releasing more heat) and the release of chloride ions on metals may combine to trigger a runaway reaction, he said.
"Starting a chain reaction requires only a very small amount of water," he said . " He estimated the amount between a pint and a quart.
A spokesman for the company, in Danbury, said that in addition to the routine inspection of the presence of chlorine, United carbide also stipulated that the tanks were built from certain types of stainless steel that would not be associated with methyl isocyanate
AdvertisementHe does not state whether the specified type of stainless steel reacts with cl-ions. Dr.
Varadarajan said that his hypothesis has been confirmed by laboratory experiments in which a isocyanate ate was aggregated or turned into a plastic in a leaking storage tank
Other contaminants may exist, but this is not the only possible explanation for the Bhopal disaster.
Although water breaks down isocyanate in the open air, it can explode with liquid chemicals in a closed tank.
The alkali can also react with it in a closed tank, but in the gas, in the sum agent or washer, in the solution of water and alkali and in the leaking gas.
In addition to water and alkali, isocyanate-based Ester reacts strongly with various contaminants (including metals such as acid, alkali and iron), usually violently.
Under certain conditions, most of these contaminants are present in factories.
Water is used to wash and condense on pipes, tanks and other equipment that are colder than the surrounding air.
Sometimes the equipment is cleaned with alkali or alkali.
Metal is a corrosion product of a stainless steel tank used to store isocyanate.
The isocyanate Technical Manual, published by United carbide in 1976, recognizes these dangers.
It says that metal contact with isocyanate acid salts can cause a "dangerous and rapid" reaction.
It added, "the evolution of heat will have a reaction to explosive violence . "
The manual says that when a chemical is not refrigerated, its reaction to water increases rapidly to the point of intense boiling.
It adds that the presence of acid or alkali greatly increases the speed of the reaction.
Pollution source investigators from India United carbide and its parent company have found evidence of at least five types of pollutant leaks in the tank, according to the New York Times, an MRI was obtained and analyzed by two Indian technical experts at the request of the New York Times.
A senior official at the Indian company said the pollutants included water, iron and alkali.
The workers speculated that the water came from the improperly sealed pipe that was cleaned, or, perhaps, was brought into the system after the nitrogen was condensed, and that the nitrogen was used to replace the air in the tank and pipe, to reduce the chance of fire.
Workers said they used nitrogen to pressurize tanks that leaked in December a few days before the accident, but did not succeed. 3.
Nitrogen should be sampled to look for traces of moisture, but "we haven't checked moisture all the time," said Mr.
Qureshi, supervisor.
The workers said that during the same period, they added alkali to the scrubber, connected to the tank by a complex set of pipes and valves that should be closed under normal circumstances, but workers say they sometimes open or leak. Dr. advertising
Varadarajan said that he was particularly upset that it was stored in such a large amount without the basic research that he believed would be sufficient for the stability of commercial isocyanate salts
He said: "I might put a small amount of kerosene in my room as my stove, but I didn't put a large can in the room.
Former officials of the Indian subsidiary said that the joint Carbide Company decided that it would be more effective to store this chemical in large quantities, and therefore, the production of pesticides that delay the production of isocyanate will not destroy its composition.
Many factories in 52-
The gallon barrel is considered to be safer than a large tank, as there are fewer quantities in each tank.
The chemical was stored in Bhopal barrels when it was imported from the United States.
In 1980, Bhopal began to produce its own methyl isocyanate salt and began storage of storage tanks.
The joint carbide technical manual of Isocyanate Ester indicates that drum storage is safer.
It says there are large storage tanks, pollution-
So the accident-
More likely.
Drums do not usually need to be refrigerated, the manual says.
But it warns that refrigeration is necessary for bulk storage.
Training is limited, and although the storage system increases the risk of failure in Bhopal, the isocyanate Ester operating manual at the plant provides little guidance in the event of a major leak.
After telling the operator that if the leakage in the tank cannot be stopped or isolated, the gas is dumped into the standby tank, the manual says: "There may be other circumstances not covered above.
The circumstances will determine the appropriate action.
As we gain practical experience, we will learn more and more.
"Some of the factory's operators are not satisfied with the equipment they are responsible. M. K.
Jain, the operator on duty on the night of the accident, said he did not understand much of the plant.
He said that he received three months of instrument training and two weeks of theoretical work, which allowed him to operate only one of several methyl acid systems.
"If there is a problem with another microphone system, I don't know how to deal with it," he said . "
Jain, a high school graduate.
AdvertisementRahaman Khan, the operator who cleaned the improperly sealed pipe a few hours before the accident, said: "I have been trained in a specific field and a specific job.
I don't know about other jobs.
During the training, they just said, "These are the valves that you should turn, and this is the system you work with, here are the instruments and their instructions. That's it.
"It's not my job on the day of the accident, sir.
Khan said he knew the pipe was not sealed but "my job is not to do anything ".
Previously, the operators said they were trained in all five systems handling the production and storage of isocyanate ester.
But they said that only a few of the approximately 20 operators in Bhopal knew about the entire isocyanate plant at the time of the accident.
The first page of the Bhopal operation manual reads: "to operate the plant, one should have sufficient knowledge of the process and the necessary skills to perform different operations in any case.
Part of the "preparation process is" if "training designed to help technicians respond to emergencies. C. S.
S. Joint carbide Inspector Tyson, who studied the Bhopal plant in 1982, recently said that "if" the lack of training was one of the major shortcomings of the plant.
In addition to training, the worker raised the issue of lower employment qualifications.
They said that the work of isocyanate salt operators who used to require a university degree in science was filled by high school graduates, and managers with experience in handling Methyl acid were often replaced by less qualified personnel, sometimes it is transferred from the combined carbide battery plant, which is less complicated than the isocyanate acid salt operation and does not have potential hazards.
The maintenance team reduced the worker also complained about the maintenance of the Bhopal plant.
Starting in 1984, they said, almost all of the major maintenance work was carried out on a day shift, with a backlog of work.
The Isocyanate operator said that the situation was more complicated because since 1983, there have been 6 operators in the shift, not 12, so there are fewer people preparing the equipment for maintenance.
The worker said that because of the backlog, the torch tower was one of the main safety systems of the plant and had stopped operating for six days at the time of the accident.
It's waiting for a 4-
They said they estimated the job would take four hours.
The staff said that the advertisement for the vent gas washer has been shut down for maintenance since October.
22, despite the factory procedure, it is "running continuously" before the factory has no toxic chemicals ".
"The factory Procedure states that the cooler must operate whenever isocyanate methane is present in the system.
The Bhopal Operating Manual states that chemicals must be kept at temperatures not higher than 5 degrees Celsius or 41 degrees Fahrenheit.
It states that a high temperature alarm is issued if the methyl isocyanate reaches 11 degrees Celsius or 52 degrees Fahrenheit.
Workers say, but the cooler is off and the chemicals are usually kept at nearly 20 degrees Celsius or 68 degrees Fahrenheit.
Factory officials have adjusted the temperature alarm to 20 degrees instead of 11 degrees, they said.
They think this temperature is good on the way to isocyanate Ester boiling point 39.
Monthly degrees Celsius, or 102.
4 degrees Fahrenheit
In addition, the 1976 Technical Manual of the United Carbide company specifically warned that if isocyanate salt is kept at 20 degrees Celsius, contaminants can trigger a reaction that is out of control.
The preferred temperature is 0 degrees Celsius or 32 degrees Fahrenheit, the manual says.
A senior official of the Indian company said that if the refrigeration unit is running all the time, it will take two days instead of two hours to react to produce the conditions that cause the leak.
This will give the factory personnel enough time to deal with the accident and prevent most, if not all, loss of life, he said.
Isocyanate acid operating manual indicates that workers who cannot control tank leakage dump some of the leaking gas to 15,000-
The gallon tank will remain empty for this purpose.
But the workers on duty said they had never opened the valve for the spare tank in the accident and their supervisor had never ordered them to do so.
The workers said they did not try to use the spare tank because its level indicator showed it was 22% full and they were concerned that the heat in the leaking tank might trigger another reaction in the spare tank.
According to the operator on duty that night, the level indicator is wrong.
The spare tank is equipped with only 437 gallons of isocyanate, not 3,300 gallons as indicated by the meter.
However, standard procedures were violated.
The operation manual says, "always empty a tank.
This will be used as a dump tank in an emergency.
It states that any tank less than 20% can be completely emptied.
A spokesman for Danbury said, "our investigators did find some microphones in the spare tank," he added: "We don't know when and how the microphone goes into the spare tank.
Next: What happened that night.
A version of the article appears on page A00001 of the National edition in January 28, 1985 with the title: Bhopal disaster: How it happened.
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