What Measures Can Be Taken To Prevent The Leakage of Chemical Reagents During The Use of Fume Hoods?

Management of reagent storage and retrieval

Store reagents properly

Classified storage: According to the properties of chemical reagents, such as acids and bases, oxidants, reductants, flammable substances, highly toxic substances, etc., they should be classified and stored. For instance, strong acid reagents such as hydrochloric acid and sulfuric acid should be concentrated in a reagent cabinet resistant to acid corrosion. Oxidants like hydrogen peroxide and potassium permanganate should be stored separately to avoid being mixed with reducing agents, so as to prevent dangers such as leakage or explosion due to mutual reactions.

Sealed storage: Ensure that the cap of the reagent bottle is well sealed to prevent the reagent from evaporating or leaking. For some volatile reagents, such as ether and acetone, reagent bottles with ground glass stoppers or rubber stoppers should be used, and sealing materials such as Vaseline should be applied to the bottle mouth to enhance the sealing effect. At the same time, the sealing condition of the reagent bottles should be checked regularly. If the bottle caps are found to be loose or the sealing materials aged, they should be replaced in time.

Control the storage quantity: Do not store a large amount of reagents in the fume hood. Only store the reagents needed for the current experiment. Excessive reagents will increase the safety hazards inside the fume hood. Once a leakage occurs, it may lead to more serious consequences. For instance, only 500 milliliters of hydrochloric acid and 200 grams of sodium hydroxide needed for the experiment on that day should be stored in a fume hood instead of keeping the entire bottle of reagents inside.

Take the reagents correctly

Use appropriate tools: According to the nature and amount of the reagent, select the appropriate tools for taking it, such as droppers, pipettes, spatulas, etc. For example, when taking a small amount of liquid reagents, use a dropper; When taking a certain volume of liquid reagent, use a pipette. When taking solid reagents, use a spatula. Avoid using inappropriate tools to prevent reagent spillage or leakage.

Standardize the operation process: When taking reagents, strictly follow the operation procedures. For instance, when using a pipette to draw liquid reagents, one should first clean and rinse the pipette. Then, insert the pipette into the reagent bottle, use a bulb to draw the reagent above the scale line, and then press the opening of the pipette with the index finger to lift the pipette out of the liquid surface. Slightly tilt the pipette to allow the solution to flow out slowly along the tube wall until the meniscus of the solution is tangent to the scale line. During the operation, be careful to avoid splashing or dripping of reagents.

Timely cleaning of residues: After taking reagents, it is necessary to promptly clean the residual reagents on the reagent bottle mouth and the taking tools. For instance, wipe the mouth of the reagent bottle with a clean paper towel, and place the pipette in the designated cleaning container for cleaning to prevent the residual reagent from dripping or evaporating and contaminating the environment inside the fume hood.

Maintenance and inspection of fume hood equipment

Regularly check the sealing of the fume hood

Check the glass window: The glass window of the fume hood is one of the important barriers to prevent reagent leakage. It is necessary to regularly check whether the sealing strips of the glass window are in good condition, and whether there is any aging, deformation or damage. If any problem with the sealing strip is found, it should be replaced in time. For instance, inspect the sealing strip of the glass window once every quarter. Gently press the sealing strip with your hand to check if its elasticity is normal and observe if there are any cracks or notches on the surface of the sealing strip.

Check the interfaces of ventilation ducts: The interfaces of ventilation ducts are also areas prone to leakage. It is necessary to regularly check whether the interfaces of the ventilation ducts are tight and whether there is any loosening or air leakage. You can apply soapy water to the interface and observe if there are any bubbles. If there are bubbles, it indicates that there is air leakage at the interface, and it should be tightened or sealed in time. For example, check the interfaces of the ventilation ducts once a month to ensure the normal operation of the ventilation system.

Maintain the exhaust system of the fume hood

Clean the fan and air duct: During long-term use, the fan and air duct of the fume hood will accumulate dust and debris, which will affect the exhaust effect and may even lead to fan failure or air duct blockage, thereby increasing the risk of reagent leakage. Regular cleaning of the fan and air duct is necessary. A vacuum cleaner or brush can be used to remove dust and debris from the fan blades and air duct. For instance, clean the fans and air ducts once every six months to ensure the exhaust capacity of the ventilation system.

Check the operating status of the fan: Regularly inspect the operating status of the fan, including its rotational speed, noise, vibration and other conditions. If abnormal fan speed, excessive noise or severe vibration is detected, the machine should be stopped immediately for inspection. The cause should be identified and maintenance carried out. For instance, check the operating status of the fan once a week, record the fan's rotational speed and noise conditions, so as to detect any abnormalities in time.

Experimental operation norms and protection

Standardize experimental operations

Control reaction conditions: When conducting chemical experiments, it is essential to strictly control reaction conditions such as temperature, pressure, and reaction time. Avoid reagent leakage or intense reaction due to out-of-control reaction conditions. For instance, when conducting certain exothermic reactions, a cooling device should be used to control the reaction temperature to prevent the reaction from being too intense, generating a large amount of gas or heat, which could lead to reagent splashing or container rupture.

Add reagents slowly: When adding reagents to the reaction system, do it slowly to avoid adding too many reagents at one time, which may cause the reaction to get out of control. For instance, when adding water to concentrated sulfuric acid, the water should be slowly poured along the wall of the container into the concentrated sulfuric acid while constantly stirring to dissipate the heat in time and prevent the liquid from splashing.

Strengthen personal protection

Wear protective equipment: When conducting chemical experiments, laboratory personnel should wear appropriate personal protective equipment, such as protective glasses, protective gloves, and protective suits. Protective glasses can prevent reagents from splashing into the eyes, protective gloves can protect the skin on the hands from being corroded by reagents, and protective suits can prevent reagents from coming into contact with the body. For example, when conducting experiments involving strong acids, strong alkalis or toxic reagents, it is necessary to wear acid and alkali resistant protective glasses, rubber gloves and chemical protective suits.

Timely handling of leakage: If reagent leakage occurs during the experiment, the laboratory personnel should immediately take measures to deal with it. For a small amount of liquid reagent leakage, absorbent paper or a cloth can be used for adsorption. For large-scale leakage of liquid reagents, sand or adsorbents can be used for covering and adsorption, and then the adsorbed substances should be collected in designated containers for treatment. At the same time, timely ventilation and air exchange should be carried out to reduce the concentration of harmful gases indoors. For instance, when a small amount of hydrochloric acid leaks, immediately use absorbent paper to absorb the leaked hydrochloric acid thoroughly, and then rinse the leaked area with clean water.