When conducting chemical experiments, safety is of utmost importance to us. This article summarizes common experimental accidents in the laboratory and our emergency response methods when accidents occur. Experimental safety concerns both you and me, with a focus on prevention.

Types of common laboratory accidents

1. Fire related accidents

Fire accidents are common and can occur in almost all laboratories. The direct cause of such accidents is:

① Forgetting to turn off the power, causing equipment or appliances to be powered on for too long, resulting in high temperatures and causing fires; On August 8, 2005, a laboratory at Capital Normal University caught fire. The cause of the fire was that Wei, a master's student at the university, was conducting experiments in the laboratory in the morning. He went out for lunch without turning off the power, and the experimental instrument "rotor" was still running. The fire was caused by a short circuit in the wires

② Aging and overloaded operation of power supply lines can cause heating and fire;

③ Improper handling or storage of flammable and explosive materials can cause the fire source to come into contact with flammable substances, resulting in a fire;

④ Littering cigarette butts and coming into contact with flammable substances can cause a fire.

2. Explosive accident

Explosive accidents often occur in laboratories with flammable and explosive materials and pressure vessels. The direct cause of such accidents is:

① Explosion caused by violating operating procedures by using equipment or pressure vessels (such as high-pressure gas cylinders);

② Equipment aging, faults or defects, causing leakage of flammable and explosive materials, and causing explosions when encountering sparks.

③ Improper handling of flammable and explosive materials resulting in combustion and explosion; Such items (such as trinitrotoluene, picric acid, ammonium nitrate, azide, etc.) will undergo violent chemical reactions when exposed to external factors such as high heat friction, impact, vibration, or other substances with conflicting properties, producing a large amount of gas and high heat, causing explosions.

④ The mixture of strong oxidants and substances with conflicting properties can decompose, causing combustion and explosion.

⑤ Explosion of instruments, equipment, drugs, etc. caused by fire accidents.

3. Toxic accidents

Toxic accidents often occur in laboratories containing chemicals and highly toxic substances, as well as in laboratories with toxic gas emissions. The direct cause of such accidents is:

① Bringing food into a laboratory with toxic substances can cause accidental ingestion and poisoning (for example, a staff member at a university in Nanjing accidentally drank intermediate products containing aniline in the refrigerator as sour plum soup during the summer, causing poisoning, because the refrigerator had previously stored sour plum soup for staff to drink);

② Equipment and facilities are aging, with faults or defects, resulting in toxic substance leakage or inability to release toxic gases, leading to poisoning;

③ Poor management, careless or irregular operations, improper handling of toxic substances after experiments, resulting in the scattering and loss of toxic substances, causing personnel poisoning and environmental pollution;

④ The blockage or disrepair of wastewater discharge pipelines can cause toxic wastewater to flow out without treatment, resulting in environmental pollution.

4. Mechanical and electrical accidents that harm human nature

Mechanical and electrical accidents often occur in laboratories with high-speed rotation or impact motion, laboratories that require live work, and some laboratories that generate high temperatures. The manifestation and direct cause of the accident are:

① Improper operation or lack of protection, resulting in squeezing, throwing, and collision injuries;

② Violating operating procedures or causing malfunctions and defects due to aging equipment and facilities, resulting in electric shock and arc sparks injuring people;

③ Improper use can cause harm to people from high-temperature gases and liquids.

5. Equipment damage accidents

Equipment damage accidents often occur in laboratories that use electric heating. The manifestation and direct cause of the accident are:

Due to line faults or lightning strikes causing sudden power outages, the heated medium cannot be restored to its original state as required, resulting in equipment damage. For example, the recent two incidents of about 20 mercury tubes being scrapped at a university in Hunan (with a loss of about 15000 yuan) were caused by sudden power outages.

Handling methods for common laboratory accidents

1. Prevention and Handling of Fire Accidents

Improper handling of volatile and flammable organic solvents such as benzene, ethanol, ether, and acetone can easily lead to fire accidents. To prevent accidents from happening, it is necessary to pay attention to the following points at all times:

(1) When handling flammable and explosive solvents, keep away from sources of ignition; The residue of explosive solids must be carefully destroyed (such as using hydrochloric acid or nitric acid to decompose metal alkynes); Do not litter unextinguished matchsticks; For substances that are prone to spontaneous combustion (such as the catalyst Raney nickel used in hydrogenation reactions) and filter paper contaminated with them, they should not be discarded casually to avoid creating new sources of ignition and causing fires.

(2) Before the experiment, carefully check whether the instrument and device are correct, secure, and tight; The operation requirements are correct and strict; During normal pressure operation, do not cause the system to be sealed, otherwise explosion accidents may occur; For liquids with boiling points below 80 ℃, water bath heating should generally be used for distillation, and direct fire heating should not be used; During experimental operations, it is necessary to prevent the leakage of organic vapors, and do not use open devices for heating. If solvent removal is to be carried out, it must be done in a fume hood.

(3) Large quantities of flammable materials are not allowed to be stored in the laboratory. Once a fire occurs during the experiment, one should not panic or lose control and should remain calm. First, immediately cut off all indoor sources of fire and power. Then rescue and extinguish the fire correctly according to the specific situation.

Common methods include:

When a flammable liquid is ignited, immediately remove all flammable substances from the ignition area, close the ventilator, and prevent further combustion.

When alcohol and other water-soluble liquids catch fire, water can be used to extinguish the fire.

When organic solvents such as gasoline, ether, and toluene catch fire, they should be extinguished with asbestos cloth or dry sand. Never use water, otherwise it will expand the combustion area.

4. When metal potassium, sodium or lithium catches fire, water, foam extinguisher, carbon dioxide, carbon tetrachloride, etc. must not be used. Dry sand and graphite powder can be used.

5. When electrical equipment wires are on fire, do not use water or carbon dioxide fire extinguishers (foam fire extinguishers) to avoid electric shock. The power should be cut off first, and then a carbon dioxide or carbon tetrachloride fire extinguisher should be used to extinguish the fire.

When clothes catch fire, do not run. Immediately cover them with asbestos cloth or thick outer clothing to extinguish the flames, or quickly remove your clothes. When the fire is intense, roll them on the ground to extinguish the flames.

When an odor or smoke is found in the oven, the power should be quickly cut off to slowly cool it down, and a fire extinguisher should be prepared for backup. Do not rush to open the oven door to avoid sudden supply of air for combustion assistance (explosion), which may cause a fire.

8. When a fire occurs, attention should be paid to protecting the scene. Major fire accidents should be reported immediately. If there are severe injuries, they should be taken to the hospital immediately.

9. Familiarize oneself with the location of fire-fighting equipment and the use of fire extinguishers in the laboratory.

When a fire occurs, three things should be done:

① Will report a fire alarm;

② Will use fire-fighting equipment to extinguish initial fires;

③ Can self rescue and escape.

Instructions for using portable dry powder fire extinguishers:

① First, tear off the small lead block and remove the safety pin;

② Use one hand to press down on the handle and then lift the fire extinguisher;

③ Hold the nozzle with the other hand and spray the dry powder jet towards the root of the flame in the combustion zone.

2. Prevention and Handling of Explosion Accidents

(1) Some compounds are prone to explosion.

For example, peroxides, aromatic polynitro compounds, nitrate esters, dry diazonium salts, azides, heavy metal alkynes, etc. in organic compounds are all explosive materials, and special attention should be paid during use and operation. When distilling ether containing peroxides, there is a risk of explosion, and the peroxides must be removed beforehand. If there are peroxides, they can be removed by adding an acidic solution of ferrous sulfate. Aromatic polynitro compounds should not be dried in an oven. Mixing ethanol with concentrated nitric acid can cause extremely strong explosions;

(2) Incorrect instrument installation or operation can sometimes cause explosions.

If distillation or heating reflux is carried out under normal pressure, the instrument must be connected to the atmosphere. Be careful not to steam the material dry during distillation. Glass instruments that are not resistant to external pressure, such as flat bottomed flasks and conical flasks, should not be used during decompression operations.

(3) When gases such as hydrogen, acetylene, and ethylene oxide are mixed with air in a certain proportion, they will form explosive mixtures that will explode upon contact with an open flame. Therefore, open flames must be strictly prohibited when using the above-mentioned substances. For synthesis reactions that release a large amount of heat, it is important to carefully and slowly add the material, pay attention to cooling, and prevent accidents caused by leakage from the piston of the dropping funnel.

3. Prevention and Handling of Poisoning Accidents

Many reagents used in the experiment are toxic. Toxic substances often cause poisoning through inhalation, skin penetration, ingestion, and other means.

When dealing with chemicals that are irritating, odorous, and toxic, 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 carried out in a fume hood. After opening the fume hood, do not insert your head into the hood and keep the laboratory well ventilated.

During the experiment, direct contact with chemicals should be avoided, especially with highly toxic substances. Organic matter adhering to the skin should be immediately washed away with plenty of water and soap. Do not use organic solvents, otherwise it will only increase the rate of chemical penetration into the skin.

Any organic matter that splashes onto the desktop or floor should be promptly removed. If the mercury thermometer is accidentally damaged, the scattered mercury on the ground should be collected as much as possible and covered with sulfur powder at the scattered location.

The highly toxic substances used in the experiment are managed by the technical leaders of each research group, distributed to the users in appropriate amounts, and the remaining ones must be recovered. The containers used for experiments with toxic substances should be labeled and cleaned promptly after use. The operating table and sink frequently used for experiments with toxic substances should be labeled. Toxic residues after experiments must be disposed of according to laboratory regulations and are not allowed to be thrown around.

If you feel symptoms such as sore throat, discolored lips or cyanosis, stomach spasms or nausea, vomiting, palpitations and dizziness during the operation of toxic substances experiments, it may be caused by poisoning. After administering the following first aid based on the cause of poisoning, immediately send the patient to the hospital for treatment without delay.

(a) Solid or liquid toxin poisoning: If the toxic substance is still in the mouth, immediately spit it out and rinse your mouth with plenty of water. For those who accidentally consume alkali, drink plenty of water first and then some milk. For those who accidentally consume acid, drink water first, then take Mg (OH) 2 emulsion, and finally drink some milk. Do not use emetics, and do not take carbonates or bicarbonates. Heavy metal salt poisoning patients should drink a glass of water solution containing several grams of MgSO4 and seek medical attention immediately. Do not take emetics to avoid causing danger or complicating the condition. Individuals with arsenic and mercury poisoning must seek emergency medical attention.

(b) Inhalation of gas or vapor poisoning: Immediately move outdoors, undo collar and buttons, and breathe fresh air. People in shock should be given artificial respiration, but not mouth to mouth method. Immediately send to the hospital for emergency treatment.

4. Prevention and Handling of Laboratory Electric Shock Accidents

Electric furnaces, electric heating sleeves, electric mixers, etc. are often used in experiments. When using electrical appliances, direct contact between the human body and the conductive parts of the appliances, as well as contact between asbestos mesh metal wires and electric furnace resistance wires, should be prevented; Do not touch the electrical plug with wet hands or by holding wet objects; It is strictly prohibited to drip water or other solvents into the electric heating sleeve to prevent electrical short circuits.

To prevent electric shock, the metal casing of the device and equipment should be connected to a ground wire. After the experiment, the instrument switch should be turned off first, and then the plug connected to the power supply should be unplugged.

To check for electrical leakage in electrical equipment, a test pen should be used. Any instrument with leakage should not be used.

First aid methods in case of electric shock:

① Turn off the power;

② Separate the wire from the victim with a dry wooden stick;

③ Separate the victim from the land, and during first aid, the rescuer must take safety measures to prevent electric shock, and their hands or feet must be insulated. If necessary, perform artificial respiration and send to the hospital for treatment.

5. First aid knowledge for other accidents in the laboratory

(1) Glass cuts: For minor injuries, the stained blood should be squeezed out in a timely manner, and glass fragments should be removed with sterilized tweezers. The wound should be washed with distilled water, coated with iodine, and then wrapped with band aids or bandages; A large wound should be immediately bandaged tightly on the upper part of the wound to stop bleeding, and rushed to the hospital for treatment.

(2) Burn: When burned by flames, steam, red hot glass, iron, etc., the wound should be immediately rinsed or soaked with a large amount of water to quickly cool down and avoid temperature burns. If blisters appear, they should not be punctured and should be wrapped with gauze before being sent to the hospital for treatment. For minor burns, apply some cod liver oil, burn ointment, or all-purpose oil to the affected area and wrap it up. If the skin is blistered (second degree burn), do not break the blister to prevent infection; If the skin at the injury site is brown or black (third degree burn), gently wrap it with dry and sterile disinfectant gauze and send it to the hospital for treatment urgently.

(3) Burns caused by acid, alkali or bromine solution:

(a) Skin burns caused by acid should be immediately rinsed with plenty of flowing water (when the skin is contaminated with concentrated sulfuric acid, do not rinse with water first to avoid strong heat release during sulfuric acid hydration and aggravating the injury. Use a dry cloth to absorb the concentrated sulfuric acid first, and then rinse with water). After thorough rinsing, neutralize with 2-5% sodium bicarbonate solution or soapy water, and finally rinse with water and apply the medicine Vaseline.

(b) Alkali burns should be immediately rinsed with plenty of flowing water, followed by further rinsing with 2% acetic acid or 3% boric acid solution, and finally rinsed with water before applying the drug Vaseline.

(c) When phenol burns, immediately wipe with 30% alcohol several times, rinse with plenty of water, and then wet compress with saturated sodium sulfate solution for 4-6 hours. As diluting phenol with water at a concentration of 1:1 or 2:1 can instantly aggravate skin damage and increase phenol absorption, do not rinse the contaminated surface with water first. After suffering from the above-mentioned burns, if blisters appear on the wound, it is not advisable to puncture the blisters. After initial treatment, the severely injured person was urgently sent to the medical room.

(4) Acid, alkali or other foreign substances splashing into the eyes:

(a) If acid splashes into the eyes, immediately rinse with plenty of water and then rinse with 1% sodium bicarbonate solution.

(b) If it is alkaline solution, immediately rinse with plenty of water and then rinse with 1% boric acid solution. When washing the eyes, keep the eyelids open and have someone help lift them open. Rinse continuously for 15 minutes. After initial treatment, severely injured individuals should be immediately sent to the hospital for treatment.

(c) If there are foreign objects such as sawdust or dust particles, someone else can open their eyelids and gently remove the foreign objects with a disinfectant cotton swab, or let them cry. After the foreign objects are discharged, a few drops of cod liver oil can be added. If glass shards enter the eyes, it is quite dangerous. At this point, try to remain calm and never rub or rub with your hands. Also, do not let others flip their eyelids, try not to move their eyes, and allow them to shed tears. Sometimes debris may flow out with the tears. Gently wrap the eyes with gauze and immediately send the injured person to the hospital for treatment.

(5) For strong acidic corrosive toxins, drink a large amount of water first, then take aluminum hydroxide paste and egg white; For strong alkaline toxins, it is best to drink a large amount of water first, and then take vinegar, sour fruit juice, and egg white. Regardless of whether it is acid or alkali poisoning, milk infusion is necessary and vomiting agents should not be taken.

(6) Mercury can easily enter the human body through the respiratory tract and can also be directly absorbed through the skin, causing cumulative poisoning.

The signs of severe poisoning include a metallic odor in the mouth and an odor in exhaled gas; Saliva, black mercury sulfide on the gums and lips; Enlargement of lymph and salivary glands. If accidentally poisoned, one should be sent to the hospital for emergency treatment. During acute poisoning, it is usually necessary to thoroughly wash the stomach with carbon powder or vomit, or consume protein (such as 1 liter of milk and 3 egg whites) or castor oil to detoxify and induce vomiting.