When we are doing chemical experiments, safety is of the utmost importance to us. This article sorts out common experimental accidents in the laboratory and our emergency handling methods when accidents occur. Experimental safety is a matter of you and me, and the focus is on prevention.
Types of common laboratory accidents
1. Fire accident
The occurrence of fire accidents is common and can happen in almost all laboratories. The direct causes of this type of accident are:
① Forgetting to turn off the power supply, causing the equipment or electrical appliances to be energized for too long, and the temperature is too high, causing fire; (August 8, 2005, a fire in a laboratory of Capital Normal University) Reason: The graduate student Wei of the school did experiments in the laboratory in the morning. He went out to eat at noon without turning off the power. The experimental instrument "rotor" was still running, and fire was caused by the short circuit of the wire)
② The power supply line was aging and overloaded, which caused the line to heat up. Causing fire;
③ Careless handling or improper storage of flammable and explosive materials, contacting the fire source with flammable materials, causing fire;
④ Throwing cigarette butts, contacting flammable materials, causing fire.
2. Explosive accident
Explosive accidents mostly occur in laboratories with flammable and explosive materials and pressure vessels. The direct causes of such accidents are:
① The use of equipment and pressure vessels (such as high-pressure gas cylinders) in violation of operating procedures leads to explosions;
② Equipment aging , There are faults or defects, causing flammable and explosive materials to leak, and sparks may cause explosion.
③ Improper handling of flammable and explosive materials, resulting in combustion and explosion; such materials (such as trinitrotoluene, picric acid, ammonium nitrate, azide, etc.) are subjected to high thermal friction, impact, vibration and other external factors or other properties When the conflicting substances come into contact, a violent chemical reaction will occur, generating a large amount of gas and high heat, causing an explosion.
④ The coexistence of strong oxidants and substances with conflicting properties can decompose, causing combustion and explosion.
⑤ Explosion of equipment, medicine, etc. caused by a fire accident.
3. Toxic accidents
Toxic accidents mostly occur in laboratories with chemicals and highly toxic substances and laboratories with toxic gas emissions. The direct causes of this type of accident are:
①Bringing food into a toxic laboratory, causing accidental ingestion and poisoning (for example, a staff member of a university in Nanjing mistakenly drank the intermediate product containing aniline in the refrigerator as sour plum soup in midsummer. The poisoning is caused because the sour plum soup for the staff was stored in the refrigerator);
②The equipment and facilities are aging, there are faults or defects, causing the leakage of toxic substances or the emission of toxic gases, which leads to poisoning;
③Improper management and operation Careless or illegal operation, improper handling of toxic substances after the experiment, causing toxic substances to be scattered and lost, causing personnel poisoning and environmental pollution;
④ The wastewater discharge pipeline is blocked or unmodified, causing toxic wastewater to flow out without treatment, causing environmental pollution.
4. Mechanical and electrical accidents
Electromechanical injury accidents mostly occur in laboratories that have high-speed rotation or impact motion, or laboratories that require live work, and some laboratories that have high temperatures. The manifestations and direct causes of the accident are:
①Improper operation or lack of protection, causing squeezing, throwing off, and collision and hurting people;
②Violation of operating regulations or faults and defects due to aging of equipment and facilities, causing electric shock and arc sparks to hurt people;
③ Improper use can cause high-temperature gas and liquid to hurt people.
5. Equipment damage accident
Equipment damage accidents mostly occur in laboratories heated by electricity. The performance and direct cause of the accident are:
Sudden power outage caused by line failure or lightning strike, causing the heated medium to fail to return to its original state as required, causing equipment damage. For example: The two incidents of scrapping about 20 mercury tubes (with a loss of about 15,000) in a university in Hunan not long ago were caused by a sudden power outage.
How to deal with common laboratory accidents
1. Prevention and treatment of fire accidents
When using volatile and combustible organic solvents such as benzene, ethanol, ether, acetone, etc., careless operation may cause fire accidents. In order to prevent accidents, the following points must be paid attention to at all times:
(1) Keep away from fire when handling and handling flammable and explosive solvents; the residues of explosive solids must be carefully destroyed (such as decomposing metal acetylides with hydrochloric acid or nitric acid); do not litter unextinguished matchsticks ; For substances that are prone to spontaneous combustion (such as Raney nickel as a catalyst for hydrogenation reactions) and filter papers stained with them, they cannot be discarded at will, so as to avoid new sources of ignition and fire.
(2) Before the experiment, carefully check whether the equipment is correct, stable and tight; the operation requirements are correct and strict; during normal pressure operation, do not cause the system to be airtight, otherwise an explosion may occur; for liquids with a boiling point below 80°C, Generally, water bath heating should be used during distillation, instead of direct heating with fire; during experimental operation, organic vapors should be prevented from leaking out, let alone heating with an open device. To remove the solvent, it must be done in a fume hood.
(3) It is not allowed to store large amounts of flammable materials in the laboratory. Once a fire breaks out during the experiment, you must not panic and keep calm. First, immediately cut off all sources of fire and power in the room. Then rescue and extinguish fires correctly according to the specific situation.
The commonly used methods are:
1. When a combustible liquid is ignited, all combustible materials in the fire area should be removed immediately, and the ventilator should be turned off to prevent expanded combustion.
2. When alcohol and other water-soluble liquids catch fire, use water to extinguish the fire.
3. When gasoline, ether, toluene and other organic solvents catch fire, use asbestos cloth or dry sand to extinguish. Never use water, otherwise it will expand the burning area.
4. When metal potassium, sodium or lithium is on fire, it must not be used: water, foam fire extinguisher, carbon dioxide, carbon tetrachloride, etc. can be used to extinguish the fire. Dry sand and graphite powder can be used to extinguish.
5. Be careful not to use water and carbon dioxide fire extinguishers (foam fire extinguishers) when the wires of electrical equipment are on fire to avoid electric shock. The power should be cut off first, and then use a carbon dioxide or carbon tetrachloride fire extinguisher to extinguish the fire.
6. When your clothes are on fire, do not run. You should immediately put them out with asbestos cloth or thick coats, or quickly take off your clothes. When the fire is large, you should roll on the ground to extinguish the flames.
7. When the oven is found to have a peculiar smell or smoke, the power should be cut off quickly to allow it to slowly cool down, and a fire extinguisher should be prepared for standby. Do not open the oven door in a hurry to avoid sudden supply of air to support combustion (explosion) and cause a fire.
- Pay attention to protect the scene in the event of a fire. Larger fire accidents should be reported to the police immediately. If anyone is seriously injured, they should be sent to the hospital immediately.
- Be familiar with the location of fire extinguishing equipment in the laboratory and how to use fire extinguishers.
When a fire occurs, there will be three meetings:
①The fire alarm will be reported;
②Fire-fighting facilities will be used to put out the first fire;
③He will save himself and escape.
How to use the portable dry powder fire extinguisher:
①Tear off the small lead block and pull out the safety pin;
②Press the handle with one hand and lift the fire extinguisher;
③Hold the nozzle with the other hand and spray the dry powder jet to the root of the flame in the combustion zone. .
2. Prevention and treatment of explosion accidents
(1) Certain compounds are easy to explode.
For example, peroxides in organic compounds, aromatic polynitro compounds and nitrate esters, dry diazonium salts, azides, acetylides of heavy metals, etc., are all explosive materials, and special attention should be paid to them during use and operation . When distilling peroxide-containing ether, there is a danger of explosion, and the peroxide must be removed in advance. If there is peroxide, it can be removed by adding an acidic solution of ferrous sulfate. Aromatic polynitro compounds should not be dried in an oven. Mixing ethanol and concentrated nitric acid will cause a very strong explosion;
(2) Incorrect equipment or incorrect operation may sometimes cause an explosion.
If distillation or refluxing is performed under normal pressure, the instrument must be open to the atmosphere. When distilling, be careful not to evaporate the material to dryness. During decompression operation, glass instruments that are not resistant to external pressure (such as flat-bottomed flasks and conical flasks, etc.) cannot be used.
(3) When hydrogen, acetylene, ethylene oxide and other gases are mixed with air to a certain ratio, an explosive mixture will be formed, which will explode when exposed to an open flame. Therefore, open flames must be strictly prohibited when using the above substances. For the synthesis reaction with a large exothermic heat, the materials should be dropped slowly and carefully, and attention should be paid to cooling. At the same time, accidents caused by the leakage of the piston of the dropping funnel should be prevented.
3. Prevention and treatment of poisoning accidents
Many reagents in the experiment are toxic. Toxic substances often cause poisoning through breathing inhalation, skin penetration, and accidental ingestion.
When handling irritating, foul-smelling and toxic chemicals, such as H2S, NO2, Cl2, Br2, CO, SO2, SO3, HCl, HF, concentrated nitric acid, fuming sulfuric acid, concentrated hydrochloric acid, acetyl chloride, etc., it must be in a fume hood In progress. After the fume hood is opened, do not put your head into the hood and keep the laboratory well ventilated.
During the experiment, avoid direct hand contact with chemicals, especially direct contact with toxic drugs. Organic matter on the skin should be washed away immediately with plenty of water and soap. Do not wash with organic solvents, otherwise it will only increase the speed at which chemicals penetrate the skin.
Organic matter splashed on the table or the ground should be removed in time. If the mercury thermometer is accidentally damaged, the mercury scattered on the ground should be collected as much as possible and covered with sulfur powder.
The highly toxic substances used in the experiment are kept by the technical person in charge of each research group, and the appropriate amount is distributed to the users and the remaining is recovered. Vessels containing toxic substances in the experiment should be labelled and cleaned promptly after use. The operation table and sink that often use toxic substances in experiments should be noted. The toxic residue after the experiment must be handled in accordance with laboratory regulations and not littered.
If you feel a burning throat, discoloration or cyanosis of the lips, stomach cramps or nausea and vomiting, palpitation and dizziness during the operation of toxic substances, it may be caused by poisoning. After giving the following first aids depending on the cause of the poisoning, immediately send to the hospital for treatment without delay.
(a) Solid or liquid poisoning: spit out the poisonous substance in the mouth immediately, gargle with plenty of water. Those who accidentally eat alkali should drink plenty of water and then some milk. Those who accidentally eat acid should drink water first, then Mg(OH)2 emulsion, and finally drink some milk. Do not use emetics, and do not take carbonate or bicarbonate. For heavy metal salt poisoning, drink a glass of water solution containing several grams of MgSO4 and seek medical attention immediately. Do not take vomiting drugs, so as not to cause danger or complicate the condition. People who are poisoned by arsenic and mercury must seek medical treatment urgently.
(b) Inhaled gas or vapor poisoning: immediately move to the outdoors, untie the collar and buttons, and breathe fresh air. People in shock should be given artificial respiration, but not mouth-to-mouth method. Send to the hospital immediately.
4. Prevention and treatment of laboratory electric shock accidents
Electric furnaces, heating jackets, electric mixers, etc. are often used in the experiment. When using electrical appliances, prevent direct contact between the human body and the conductive parts of the electrical appliances and the asbestos mesh wire and the resistance wire of the electric furnace; do not touch the electrical plug with wet hands or wet objects. ; It is strictly forbidden to drip water and other solvents into the heating jacket to prevent electrical short circuit.
In order to prevent electric shock, the metal shell of the device and equipment should be connected to the ground wire. After the experiment, the switch of the instrument should be turned off, and then the plug connected to the power supply should be removed.
A test pencil should be used to check whether electrical equipment is leaking. Any leaking instrument cannot be used.
First aid methods in the event of an electric shock:
①Turn off the power supply;
②Use a dry wooden stick to separate the wire from the victim;
③Separate the victim from the ground. The first aider must take safety measures to prevent electric shock and insulate hands or feet. If necessary, give artificial respiration and send to hospital for treatment.
5. First aid knowledge for other accidents in the laboratory
(1) Glass cuts: For minor injuries, squeeze out the dirty blood in time, and use sterilized tweezers to remove the glass fragments, wash the wound with distilled water, apply iodine, and bandage it with bandages or bandages; large wounds should be used immediately The upper part of the wound was tied tightly with a bandage to stop the wound from bleeding, and he was rushed to the hospital for treatment.
(2) Burns: When burned by flame, steam, red-hot glass, iron, etc., immediately wash or soak the wound with plenty of water to cool down quickly to avoid temperature burns. If blisters occur, they should not be broken. They should be bandaged with gauze and sent to hospital for treatment. For minor burns, apply some cod liver oil or scald ointment or Wanhua oil to the wound and bandage it. If the skin blisters (second-level burns), do not break the blisters to prevent infection; if the wounds are brown or black (third-level burns), they should be gently wrapped with dry and sterile sterile gauze and sent to hospital for treatment.
(3) Burned by acid, alkali or bromine solution:
(a) If the skin is burned by acid, rinse immediately with a lot of running water (when the skin is contaminated with concentrated sulfuric acid, do not rinse with water first, so as to avoid the strong heat generation when sulfuric acid hydrates and aggravate the injury. You should use a dry cloth to absorb the concentrated sulfuric acid, and then Rinse with clean water), after thorough rinsing, neutralize with 2 to 5% sodium bicarbonate solution or soapy water, and finally rinse with water and apply the medicine petroleum jelly.
(b) lye burns should be rinsed immediately with a large amount of running water, and then further rinsed with 2% acetic acid or 3% boric acid solution, and finally rinsed with water, and then coated with the drug Vaseline.
(c) When phenol burns, immediately wipe with 30% alcohol several times, then rinse with plenty of water, and then wet it with sodium sulfate saturated solution for 4-6 hours. When phenol is diluted with water at 1:1 or 2:1 concentration, it will be instantly It can aggravate skin damage and increase phenol absorption, so do not rinse the contaminated surface with water first. After the above-mentioned burns, if blisters appear on the wound surface, it is not advisable to break the blisters. After initial treatment, the seriously injured were rushed to the infirmary.
(4) Acid, lye or other foreign objects splashed into the eyes:
(a) If acid is splashed into the eyes, rinse immediately with plenty of water, and then rinse with 1% sodium bicarbonate solution.
(b) If it is lye, rinse immediately with plenty of water and then rinse with 1% boric acid solution. Keep your eyelids open when you wash your eyes. You can open your eyelids with the help of others and continue to rinse for 15 minutes. The seriously injured were immediately sent to hospital for treatment after preliminary treatment.
(c) If there are foreign objects such as sawdust, dust particles, etc., others can open the eyelids and gently remove the foreign objects with a sterile cotton swab, or allow them to weep. After the foreign objects are discharged, add a few drops of cod liver oil. It is more dangerous if glass chips enter the eyes. At this time, try to stay calm, never rub with your hands, don't let others roll your eyelids, try not to move your eyeballs, but let them shed tears. Sometimes the debris will follow the KC certification. Please add a link to describe the tears. After gently wrapping the eyes with gauze, immediately send the injured to the hospital for treatment.
(5) For strong acid corrosive poisons, drink a lot of water first, then aluminum hydroxide paste and egg white; for strong alkaline poisons, it is best to drink a lot of water first, and then take vinegar, sour juice, and egg white. Regardless of acid or alkalosis, milk must be poured, and vomiting should not be taken.
(6) Mercury easily enters the human body from the respiratory tract, and can also be directly absorbed through the skin to cause cumulative poisoning.
Signs of severe poisoning are metal odor in the mouth and smell of exhaled air; saliva, the black color of mercury sulfide on the gums and lips; swollen lymph glands and salivary glands. In case of accidental poisoning, you should be sent to the hospital for emergency treatment. In acute poisoning, gastric lavage is usually done with toner or vomiting agent, or protein (such as 1 liter of milk plus 3 egg whites) or castor oil is used to detoxify and vomit.