What Are The Safety Points for Fume Hoods When Handling Flammable And Explosive Reagents?

When fume hoods handle flammable and explosive reagents, the following safety points must be strictly followed:

Preparations before the experiment

Check the status of the fume hood: Before use, carefully inspect whether the power supply, water supply and drainage, gas and other switches and pipelines of the fume hood are normal to ensure that it is in good operating condition. Turn on the lighting equipment and check whether the sight light source and the interior of the cabinet are normal. Turn on the exhaust fan and listen carefully to see if it operates normally. Generally, there should be no obvious abnormal sounds within about 3 minutes. If there are any problems, the use should be stopped and the relevant departments or personnel should be notified for handling.

Familiarize yourself with the properties of reagents: Get familiar with the properties of flammable and explosive reagents in advance, including their flash point, ignition point, explosion limit, etc., so as to take corresponding protective measures during the experiment. Make sure that the chemicals handled in the fume hood do not react with each other to avoid danger.

Experimental Operation Specifications

Take good personal protective measures: Laboratory personnel should wear work clothes, gloves and goggles. When necessary, they should also wear protective face masks and gas masks. When using an electric stove or operating high-temperature equipment, protective gloves must be worn to prevent burns.

Standard operation window: Move the upper and lower Windows slowly and gently to avoid hasty operation. During the experiment, the height of the window from the table surface should be 100 to 150mm. This not only ensures ventilation but also protects the upper part of the operator's chest. At the same time, personnel should keep a distance of 15cm from the fume hood. Their heads and upper bodies must not be inserted into the hood.

Proper placement of items: Do not place any equipment or reagents within 150mm of the glass window. When placing large-sized instruments and equipment in a fume hood, sufficient space should be left, and no items should be piled up around to ensure that the air flow is not affected. Items placed should be at least 15cm away from the inner side of the adjustable door to prevent them from falling. Power sockets should not be installed in fume hoods involving flammable and explosive organic reagents to prevent accidents such as fire and explosion. Do not leave disposable gloves or light plastic bags in the fume hood to avoid blocking the exhaust.

Control experimental conditions: Strictly control experimental conditions such as temperature, pressure, reaction time, etc. Avoid reagent leakage or intense reaction due to out-of-control reaction conditions. For instance, when conducting heating experiments involving flammable and explosive reagents, appropriate heating equipment should be used and the heating temperature should be strictly controlled to prevent explosions caused by excessively high temperatures.

Monitoring of the experimental process

Observe the ventilation effect: During the experiment, constantly monitor the ventilation effect of the fume hood. When the fume hood is in operation, paper can be placed at the hood opening to test the ventilation effect, ensuring that the face air velocity at the hood opening is controlled within 0.35-0.75m/s, usually set at 0.5m/s, to guarantee that harmful gases can be discharged in a timely manner.

Timely handling of abnormalities: In the event of dangerous situations such as chemical splashing or fire, the power supply should be immediately cut off, and corresponding emergency measures should be taken based on the specific circumstances. In case of a small-scale fire, fire extinguishers can be used to put it out. If the fire is large, evacuate the scene immediately and call the fire alarm number.

Post-experiment processing

Continuous exhaust: Before the experiment ends, the fan should continue to run for at least 5 minutes before being turned off to ensure that all residual gases in the pipeline are completely discharged, preventing the accumulation of flammable and explosive gases in the fume hood and causing danger.

Clean the fume hood: After use, clean the reagents, chemicals, instruments and equipment, etc., and wipe the inside and outside of the hood clean. If there is pollution, warning signs should be posted and other people should be informed to avoid unnecessary harm. After that, close all the switches and Windows.

Daily maintenance and management

Regular inspection and maintenance: Conduct a comprehensive inspection and maintenance of the fume hood on a regular basis, including checking whether the ventilation ducts are unobstructed, whether the fans are operating normally, and whether the sealing strips are aged, etc. It is recommended to conduct a regular inspection once a month and a comprehensive maintenance every six months to ensure that the fume hood is always in good operating condition.

Avoid illegal storage: It is prohibited to store or experiment with flammable and explosive items in the fume hood, and it is also forbidden to store waste in the fume hood for a long time. A fume hood is not a storage cabinet. Inside the cabinet, apart from necessary instruments, consumables and a small amount of commonly used reagents, it should avoid storing too many items.