Maintenance and Cleaning Methods for Common Laboratory Instruments

News 31 7 月, 2024

Laboratory instruments are essential partners in our work. Proper use and maintenance habits can make our experiments smoother and more efficient. So, how should these instruments be maintained? Let’s explore some key methods together.

Electronic Balance

Electronic balances are indispensable for weighing in experiments. While most lab personnel are familiar with their operation, maintenance and cleaning are often neglected. Residues and stains left on the balance pan can reduce the sensitivity and accuracy of the balance and shorten its lifespan. Preheat the electronic balance for 10 minutes before use, as directly weighing items immediately after turning it on is a common mistake.

Ensure that the temperature of the item to be weighed matches the balance’s temperature. Avoid placing extremely hot or cold objects directly on the balance pan. Volatile or corrosive reagents should be weighed in sealed containers, and remember to close the side doors of the balance during weighing. After use, clean the balance pan and surrounding areas thoroughly.

In humid environments, rust may form on the balance. Use mechanical methods to remove rust, such as scraping or sanding, and apply a protective layer afterward. When not in use, close the side doors, cover the balance with a cloth, and store it in a dry, shaded area.

Electric Thermostatic Drying Oven

Electric thermostatic drying ovens are used for baking and drying items in chemical experiments. The operating voltage is 220V, and the temperature should be maintained between 100 to 110 degrees Celsius. Avoid placing flammable or volatile chemicals inside. Items should be centrally placed on the shelf to ensure even air circulation and temperature distribution.

Do not touch the oven body or switches with wet hands during use. If abnormal situations like odors or smoke occur, immediately turn off the power and consult a professional. Regularly wipe the inner walls and surface to keep them clean and maintain glass transparency. If the oven is not used for an extended period, unplug it and run it for 2-3 days periodically to eliminate moisture and prevent damage.

Thermostatic Water Bath

Thermostatic water baths are essential for distillation, drying, and chemical concentration in labs. They also serve as a constant temperature heating source for various experiments.

Before use, ensure students understand the operation and safety precautions. Never connect the power before adding water, preferably distilled to prevent scaling. Do not overfill to avoid overflow when boiling, and ensure the water level is above half the height of the heating tube. Avoid water getting into the control box to prevent electric shock. If temperature control fails, clean the silver contacts on the controller with fine sandpaper. After use, remove the items, turn off the power, drain the water, and record the usage.

Beaker

Beakers are commonly used for holding liquids, preparing solutions, and simple chemical reactions. However, they should not replace graduated cylinders for precise measurements. Use a wire gauze when heating a beaker to distribute the heat evenly and prevent glass breakage. Do not heat beakers directly with a flame, as uneven heating can cause them to crack. When heating liquids in a beaker, fill it no more than one-third full to prevent spillage.

Test Tube

Test tubes are used for holding small amounts of substances and heating reactions. Do not fill a test tube more than half its capacity with liquids or one-third for heating. Use tweezers to place solid materials inside to avoid breaking the tube. When heating, use a test tube holder and avoid pointing the open end at people. Preheat the test tube before direct heating, tilt it at about 45 degrees for liquids, and keep the exterior dry to avoid breakage.

Volumetric Flask

Volumetric flasks are used for preparing precise solution concentrations. They have a long neck and a ground glass stopper, with a marked line indicating the volume at a specific temperature. Use the flask only to prepare solutions up to its marked volume, and check for leaks before use. Dissolve solutes in a beaker before transferring to the flask, and use a glass rod to direct the flow.

Burette

Burettes are used to measure variable volumes of liquid in titration analyses. Acid burettes with glass stopcocks are used for acidic substances, while base burettes with rubber tubes are for alkaline substances. Ensure no leaks before use, and rinse with the solution to be measured. During titration, keep the burette vertical and add the solution drop by drop near the endpoint. Read the volume to two decimal places and dispose of remaining solutions properly.

Washing Common Glassware

Glassware such as beakers, test tubes, burettes, and volumetric flasks must be cleaned thoroughly after use to prevent contamination and ensure accurate results. Rinse with tap water, use a brush with detergent, and rinse again until a uniform water film forms. For oily residues, wash with an alkaline alcohol solution followed by detergent and water. For rust and scale, soak in hydrochloric acid, then rinse. Delicate items can be soaked in detergent for easier cleaning.

Maintaining and Cleaning Optical Instruments

Optical instruments like spectrophotometers and refractometers require careful handling and cleaning. Avoid disassembling parts or exposing them to harsh conditions. After use, clean lenses and prisms with distilled water, and if necessary, a mixture of ethanol and ether. Use lens paper or cotton balls with minimal cleaning solution, wiping gently from the center outward. Store in a dry, dust-free environment to prevent corrosion.

Conclusion

Proper maintenance and cleaning of laboratory instruments are crucial for ensuring their longevity and accuracy. Following these guidelines helps maintain a clean and efficient lab environment, ultimately leading to more reliable experimental results.