How to maintain laboratory equipment

Laboratory equipment maintenance 

Once the instrument absorbs dust and dirt, it will not only affect the performance of the instrument, shorten the service life, directly affect the experimental results, but also affect the appearance and the physical and mental health of the experimenter. Frequent dust removal and cleaning is an important part of good instrument maintenance.

(一）Dust removal

There are many ways to remove dust, mainly depending on the degree of dust adhesion. In dry air, if there is little dust or the dust has not yet become damp, you can wipe it with a dry cloth or a towel, or use a soft brush to remove the dust on the general instrument; The dust inside the instrument can be blown with a pump to remove dust; When the air is humid and the dust has formed scales, the dust should be wiped with a damp cloth, but it is not suitable for discolored surfaces and electrical appliances. If the dirt is not easy to wipe clean, wipe it with a cotton ball moistened with alcohol, or clean it.

(二) Cleaning

The instrument will be stained with greasy, glue, sweat and other dirt during use, and rust and mildew will occur when stored carelessly. These dirt will have an extremely bad effect on the life and performance of the instrument. There are usually two cleaning methods for the instrument. One is mechanical cleaning, that is, cleaning with shovel, scraping, brushing, etc.; the other is chemical cleaning, that is, cleaning with various chemical decontamination solvents. The specific cleaning method depends on the condition of the dirt attached to the surface and the nature of the dirt. The following describes the cleaning methods of several common instruments and parts of different materials.

1. Cleaning of glassware

There are roughly two types of dirt attached to glassware. One type can be cleaned with water, and the other type can only be cleaned with cleaning agents or special detergents.

The glassware containing sugar, salt, starch, silt, alcohol, etc. can be cleaned by washing with water. It should be noted that if the attached dirt is dry and hard, the glassware can be soaked in water for a period of time, and then flushed with a brush until it is washed.

Glassware stained with oil or filled with animal or vegetable oil can be cleaned with washing powder, decontamination powder, detergent, etc. Use a brush to clean the glassware. After cleaning the glassware with detergent, rinse it with clean water.

Organic solvents such as gasoline and benzene should be used to clean glassware with tar, asphalt or other high molecular organic substances. If it is still difficult to clean, the glassware can be soaked in alkaline detergent for a period of time, and then washed with a solution of sodium carbonate, sodium bicarbonate, sodium hydroxide or sodium phosphate with a concentration of more than 5%, or even heated.

In chemical reactions, metal, oxides, acids, alkalis and other contaminants are often attached to the walls of glassware. When cleaning, according to the characteristics of the dirt, use strong acid, strong alkali to clean or use the method of neutralizing chemical reaction to remove the scale, and then rinse with water. When using acid and alkali cleaning, special attention should be paid to safety. The operator should wear rubber gloves and protective glasses; tweezers, clamps and other tools should be used during operation, and glassware should not be removed by hand.

2. Cleaning of optical glass

Optical glass is used in instrument lenses, prisms, glass slides, etc., which are easily stained with oil and fingerprints during manufacturing and use, which affect imaging and light transmittance. To clean optical glass, you should choose different cleaning agents, use different cleaning tools, and choose different cleaning methods according to the characteristics and different structures of the dirt.

To clean the lens with AR coating, such as the lens of camera, slide projector, microscope, use about 20% alcohol to prepare cleaning agent for cleaning. When cleaning, use a soft brush or cotton ball moistened with a small amount of detergent, and make a circular movement from the center of the lens outward. Do not soak this kind of lens in cleaning agent for cleaning; do not wipe the lens forcefully, otherwise it will scratch the AR coating and damage the lens.

Mold on the surface of optical glass is a common phenomenon. When the optical glass is moldy, the light will scatter on its surface, making the image blurry. In severe cases, the instrument will be scrapped. The mildew of optical glass is mostly due to the microbial spores attached to its surface. When the temperature and humidity are suitable, and there are required "nutrients", it will grow rapidly and form mildew spots. It is particularly important to prevent mildew and stains on optical glass. Once mildew occurs, it should be cleaned immediately.

To eliminate mildew, the mold can be cleaned with a cleaning agent made up of 0.1 to 0.5% ethyl hydrogen-containing dichlorosilane and anhydrous alcohol, or with propylene oxide, dilute ammonia, etc.

3. Cleaning of rubber parts

There are many parts made of rubber in the experimental instrument. As a kind of high molecular organic matter, rubber will age when it is stained with greasy or organic solvents, which will cause the parts to deform, soften and become sticky.

To clean oil stains on rubber parts, alcohol, carbon tetrachloride, etc. can be used as cleaning agents, but organic solvents cannot be used as cleaning agents. When cleaning, first wipe with a cotton ball or silk cloth dipped in the cleaning agent, and wait for the cleaning agent to evaporate naturally. It should be noted that carbon tetrachloride is toxic and harmful to the human body. It should be cleaned under better ventilation conditions and pay attention to safety.

4. Cleaning of plastic parts

There are many types of plastics, including polystyrene, polyvinyl chloride, nylon, plexiglass and so on. Plastic parts are generally very sensitive to organic solvents. When cleaning dirt, organic solvents such as gasoline, toluene, and acetone cannot be used as cleaning agents. It is advisable to scrub the plastic parts with a detergent prepared with water, soapy water or washing powder.

5. Rust removal of steel parts

Steel parts are very easy to rust. In order to prevent corrosion, steel parts in teaching equipment are often coated with protective layers such as oil layer and paint, but even so, rust often occurs. To remove the corrosion of steel parts, different methods should be adopted according to the degree of corrosion and the characteristics of the parts.

For steel parts with large size, low precision or mechanical methods that are not easy to remove, chemical methods can be used to remove rust, such as immersing the parts to be derusted with phosphoric acid with a concentration of 2-25%, and heating during soaking, the temperature should be 40～80℃. After the rust is removed, a protective film will be formed on the surface. Then the parts are taken out and soaked in a phosphoric acid solution with a concentration of 0.5-2% for about one hour, and finally taken out and dried.

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