Handling Laboratory And Chemical Apparatus

Introduction

Laboratory equipment can be hazardous if they are not used and maintained properly. Laboratory personnel must be trained on the proper use of laboratory equipment prior to using the equipment. Glassware is designed for a specific purpose. It should only be used for that purpose. "Makeshift" apparatus may be unstable and could lead to accidents and injuries.

When selecting glassware, determine the compatibility of the glassware with the chemicals or process. Some chemicals react with glass or cause damage (etch) glass.

If your process involves temperature or pressure changes, ensure the glassware can withstand the changes. Many dangers lurk in the laboratory. The most obvious risks are chemical hazards, but unsafe usage of laboratory apparatus can lead to disastrous consequences as well. There are certain procedures which must be observed when handling laboratory apparatus to reduce accidents and prevent injury.

Working safely with hazardous chemicals requires proper use of laboratory equipment. Maintenance and regular inspection of laboratory equipment are essential parts of this activity.

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Many of the accidents that occur in the laboratory can be attributed to improper use or maintenance of laboratory equipment. This chapter discusses prudent practices for handling equipment used frequently in laboratories.

The most common equipment-related hazards in laboratories come from devices powered by electricity devices for work with compressed gases, and devices for high or low pressures and temperatures. Other physical hazards include electromagnetic radiation from lasers and radio-frequency generating devices. Seemingly ordinary hazards such as floods from water-cooled equipment, accidents with rotating equipment and machines or tools for cutting and drilling, noise extremes, slips, trips, falls, lifting, and poor ergonomics account for the greatest frequency of laboratory accidents and injuries.

SAFETY IN THE USE OF LABORATORY EQUIPMENT

Glassware

The primary hazards associated with laboratory glassware are cuts from broken glassware, puncture wounds from attempting to force thermometers or glass tubing into stoppers, and burns from inadvertently touching heated glassware. Laboratory glassware should never be used for food or beverages. When using glass tubing, all cut ends should be fire polished. Use a dustpan and brush, not your hands, to pick up broken glass. Broken glass should be discarded in a separate designated container. Use the right size and type of glassware for any given operation. Wear proper cut‐resistant gloves when inserting or removing glass tubing from flexible tubing or a stopper. Ensure that stopper holes are appropriately sized and carefully insert tubing by gently twisting back and forth.

When cutting a piece of glass tubing, score a line using a file or equivalent. Wrap a cloth or paper towel around the tubing and break at the score over a piece of cloth/paper to catch any pieces.

Centrifuges

Most hazards associated with centrifuges are due to the processing of hazardous materials and poor mechanical conditions.  Ensure centrifuges have an interlocking device that will prevent both the lid from being opened when the rotor is in motion and the centrifuge from starting when the lid is open.  Inspect the centrifuge tubes prior to use for stress lines, hairline cracks and chipped rims. Ensure the centrifuge is properly balanced. Load the rotor with samples arranged symmetrically. Opposing tubes must be of equal weight. If necessary, use “water blank” tubes to balance sample tubes of unequal weight. Avoid over‐filling the tubes.

Use caps or stoppers on centrifuge tubes. Avoid using lightweight materials such as aluminum foil as caps. Do not open the lid during or immediately after operation, attempt to stop a spinning rotor by hand or with an object, or interfere with the interlock safety device. Decant supernatants carefully and avoid vigorous shaking when re‐suspending. Never exceed the specified speed limitations of the rotor. Inspect the O‐ring on the rotor lid regularly and replace if cracked or dry. Never operate a centrifuge if the rotor lid is missing its O‐ring. Do not leave the centrifuge until it has reached its programmed speed.

Decontaminate the outside of the cups/buckets and rotors before and after centrifugation. Unless fitted with a suitable exhaust system, do not centrifuge materials capable of creating flammable or explosive vapors. Immediately abort the run if you hear abnormal vibration, whining or grinding noises. At the end of the run, ensure the rotor and centrifuge are cleaned according to the manufacturer’s instructions. Do not use abrasive cleaners. Rotors are easily damaged. Do not use metal tools to remove tubes or clean. Do not attempt to move the centrifuge while it is in operation.

Gas Burners

All laboratory workers using gas burners shall follow these guidelines:

Place the burner away from any overhead shelving or equipment. Remove all papers, notebooks, combustible materials and containers of flammable chemicals from the area surrounding the burner. Tie‐back long hair, remove dangling jewelry and secure any loose clothing. Inspect the rubber tubing for cracks, holes, or other defects and ensure that the hose is securely connected on the gas valve and the burner. Report any damage to the laboratory supervisor and replace any defective parts.

Inform others in the laboratory that the burner will be in use. Use a burner sparker to ignite the gas burner. Never use a match or cigarette lighter to ignite a burner. Hold the sparker above the burner before turning on the gas and ignite immediately after opening the gas valve. Adjust the flame by turning the collar to regulate airflow and produce an appropriate flame. Do not leave open flames unattended. Never leave the laboratory while the burner is on. Turn off the gas when the burner is no longer needed. Ensure the main laboratory gas valve is off before leaving the laboratory. Regularly inspect all gas valves in the laboratory to ensure they are completely shut off.

Heating and Cooling Glassware

Check with the glassware manufacturer to determine safe temperature usage. Most glassware can only be exposed to certain high and low temperatures. Usage outside of those ranges may cause damage or breakage to the glassware. Always watch evaporation closely. A vessel, heated after evaporation has already occurred, may crack. Do not put hot glassware on cold or wet surfaces as it may break with temperature change. Never heat glassware that is etched, cracked, chipped, nicked or scratched. Glassware with thick walls (e.g. bottles and jars) should never be heated over a direct flame. Additionally, do not heat glassware directly on electrical heating elements. Do not look down into a vessel being heated.

Cool all glassware slowly to prevent breakage, unless using specifically designed glassware. Use care when removing glassware from ultra-low temperature freezers (-70 to -150 C) to prevent thermal shock and cracking. For best results, immediately rinse the entire bottle under cold running water until thawing begins. Never place bottles directly from the freezer into warm water baths.

When using a Bunsen burner, the flam should touch the glass below the liquid level. A ceramic-centered wire gauze will diffuse the burner flame to provide more even heat. Always use hotplates that are larger than the bottom of the vessel being heated. Thick-walled glassware (e.g. jars, bottles, cylinders, and filter flasks) should never be heated on hot plates. When using a hot/stir plate, ensure that only the settings necessary are activated (i.e. if you do not intend to heat, ensure the hot plate is NOT turned on.

Cleaning and Drying Glassware

Good lab technique necessitates the use of clean glassware. Glass must be physically clean, chemically clean, an in many cases, sterile. Many glassware accidents occur during cleaning. Some reminders when washing and drying glassware. Eye protection and heavy-duty slip-resistant and chemically resistant gloves should be worn when washing glassware. Wash glassware as quickly as possible after use. The longer it is left unwashed, the harder it will be to clean. If necessary, allow harder to clean apparatus to soak in soapy water. Do not overload sinks, dishwashers, or soaking bins.

Keep glassware clear of the sides of the sink. Rubber sink and counter mats can also help reduce the risk of breakage and injury. Never use worn out cleaning brushes; they can scratch or abrade the glass. Specialized training in the safe usage of caustic cleaning agents must be completed before using aqua-regia, chromic acid or other reactive solutions to clean glassware. When drying glassware, place articles on towels, lined basket, or slip-resistant pads. Be sure to place away from the edge of the bench. Large containers may be hung on pegs to dry. When cleaning pipettes, place pipettes, tips down, into a cylinder or tall jar of water or appropriate disinfectant (e.g. for biologically contaminated tips). A pad of cotton or glass wool at the bottom will help prevent breakage of the tips. Ensure the water or disinfectant level is high enough to immerse the pipettes. New glassware should be washed before use to remove any residue or loose particles.

Disposal and Spill Clean-up

Spills and Broken Glass

Glass is fragile and breaks easily. When glass breaks, care should be taken to reduce the risk of cuts. If something is falling, let it drop! Catching it may cause the glassware to break in your hand. Wear cut-resistant gloves when handling broken glass. Disposal nitrile or latex gloves should NEVER be worn. Glass will cut through those gloves. When cleaning broken glass, use mechanical means to pick up the pieces. Tongs, tweezers, or forceps should be used to pick up large pieces of broken glass. Small shards can be picked up using a wet paper towel or absorbent pad or by using rolled-up tape.

Disposal

Proper disposal ensure that others aren't injured by improperly disposed of broken glass.
Contaminated broken glass
Place in rigid, puncture-resistant container (e.g. sharps container). For biologically contaminated broken glass, closed and sealed container should be placed in bio hazardous waste box for disposal. For chemically contaminated broken glass, closed and sealed containers should be tagged as chemical waste. Uncontaminated broken glass

Uncontaminated broken glass may be disposed of in a broken glass box or uncontaminated waste box.

Activity

Objectives: Let’s see if you can recall the things that you learned and how sharp your eyes is! Find the following words that is related on what have you learned from the topic.

References:

http://www.ncbi.nlm.nih.gov/books/NBK55884/
http://www.uvm.edu/safety/lab/safe-handling-of-glassware
https://www.sigmaaldrich.com/content/dam/sigma-aldrich/docs/Sigma-Aldrich/Usage/1/glass_care_safe_handling.pdf http://mdk12.org/instruction/curriculum/science/safety/handling.html