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Taboos of laboratory operation (1)

The following operations are taboos for those who have been living in the laboratory all the year round. Xiao Bian sorted them out today and quickly forwarded them to everyone to learn!

1. Refrigerator bomb

During extraction or dialysis, organic reagents are used and placed in the refrigerator open. As the organic gas reaches the critical concentration, it is ignited by the electric spark when the refrigerator compressor is started.

On October 6, 1986, a refrigerator in a research institute of the Chinese Academy of Sciences exploded;

On December 15, 1987, a refrigerator in a laboratory of Ningxia Academy of Agricultural Sciences exploded;

On July 20, 1988, the “Shasong” refrigerator in the home of a teacher at Nanjing Normal University exploded.

In just a few years, there were more than 10 reported refrigerator explosions. The cause of the accident was not the quality of the refrigerator itself, but the chemicals such as petroleum ether, acetone, benzene and butane gas were placed in the refrigerator. We know that the temperature in the refrigerator is low. If flammable and explosive chemicals with low boiling point and flash point are placed in the refrigerator, they will volatilize flammable gas under low temperature conditions. Even if the bottle cap is tightly twisted, the low temperature will often cause the bottle shell to shrink, the gas valve to loosen or even the bottle shell to crack. The volatile combustible gas mixes with the air to form an explosive mixture and fills the refrigerator. The electric spark generated when the temperature control switch (or other control switches) is opened or closed is very easy to explode. Therefore, refrigerator users must not store chemicals in the refrigerator.

 

2. Pour alcohol with open fire

Open the burning twist of the alcohol lamp with pliers, and pour alcohol into the alcohol lamp with one hand, which may cause the whole bottle of alcohol to burn and explode.

3. Liquid nitrogen bomb

Use glass and buckle cover centrifuge tubes to pack samples and put them into liquid nitrogen tanks. When they are taken out, the properties of the pipe wall have changed, and they cannot withstand the expanding gas pressure, or the pressure is uneven when they are rapidly warming up, causing explosion.

 

Therefore, people who wear glasses have an advantage – “Long live glasses!”

 

Operators who frequently carry out liquid nitrogen shall wear plastic goggles.

 

Hazard Overview

Health hazard: This product is incombustible and asphyxiant, and skin contact with liquid nitrogen may cause frostbite. If the nitrogen produced by vaporization is excessive under normal temperature, the partial pressure of oxygen in the air will drop, causing anoxic asphyxia.

 

First aid measures

Skin contact: If there is frostbite, seek medical treatment.

Inhalation: quickly leave the site to fresh air and keep breathing smooth. If breathing is difficult, give oxygen. If breathing stops, conduct artificial respiration immediately and seek medical advice.

 

Fire fighting measures

Hazard: In case of heat, the internal pressure of the container will increase, which may cause cracking and explosion.

Extinguishing method: This product is incombustible, and the containers in the fire site shall be kept cool with foggy water. The vaporization of liquid nitrogen can be accelerated by spraying water in the form of mist, and the water gun shall not shoot liquid nitrogen.

 

Leakage emergency treatment

Emergency treatment: quickly evacuate the personnel in the leakage contaminated area to the windward place, isolate them, and restrict access. Emergency personnel shall wear self-contained positive pressure respirators and cold clothing. Do not touch the leakage directly. Cut off the leakage source as much as possible. Prevent gas from gathering in low recesses and exploding when encountering point heat source. Use the exhaust fan to send the leaked gas to the open space. Leaking containers shall be properly treated, repaired and inspected before use.

 

Handling and storage

Precautions for operation: closed operation, providing good natural ventilation conditions. Operators must be trained and strictly abide by the operating procedures. It is recommended that operators wear cold proof gloves. Prevent gas leakage into the air of the workplace. The cylinders and accessories shall be handled with care to prevent damage. Equip emergency equipment for leakage.

 

Precautions for storage: Store in a cool and well ventilated place, and the temperature should not exceed 50 ℃.

 

Personal protection

Respiratory system protection: no special protection is required generally. However, when the air oxygen concentration in the workplace is lower than 19%, air respirators, oxygen respirators and long tube masks must be worn.

Eye protection: wear a safety mask.

Hand protection: wear cold proof gloves.

Other protection: Avoid inhalation of high concentration to prevent frostbite.

 

……

To be continued

 


Post time: Oct-08-2022