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©HIVE® Laboratory Safety & Data Sheets
(Rated as: Excellent)
Work in infinite Progress (LT/)
The RULE: You must wear your safety glasses at all times in the laboratory even if you aren't "doing anything".
Don't believe it? Read a terrific example of what can happen when incompatibles are mixed!http://www.ilpi.com/safety/explosion.html
Chem Lab Accident Prevention (06-11-04):
Chemical Formulary, Vol. IX. (Miscellaneous Chapter)
ACIDS & BASES
. Whenever a substance enters the eye, flush with water for 15 minutes and get prompt medical attention.
=== An acidic solution is defined as one that has a pH less than 7.0.
. All of the following are strong acids, meaning that they completely dissociate into ions and form H+ in aqueous (water) solution. For example:
HCl -> H+ + Cl-
Chemists will tell you that the following equation is more correct because H+ ions (sometimes referred to as "protons") actually exist as H3O+ ions (called hydronium cations) in water:
HCl + H2O -> H3O+ + Cl-
They will cause severe and immediate burns upon skin contact :
The acids listed above are all examples of inorganic acids, sometimes called mineral acids. Mineral/inorganic acids can be strong or weak.
Weak acids do not dissociate completely into ions. Examples of these include acetic acid (a 5% solution of acetic acid in water is called vinegar), formic acid, ammonium cation (NH4+), and water itself. The strength of acids can be measured using the pH scale. The lower the pH, the greater the acidity of a solution.
Substances with names that end in "oic acid" or "ic acid" are organic acids called carboxylic acids. Two of the examples we just looked at, formic acid and acetic acid are carboxylic acids.
!!! Just because an acid is weak does not mean that it can't harm you. For example, HF, hydrofluoric acid, is a weak inorganic acid. When you spill it on your hand it doesn't burn...but over the course of hours it migrates to the bones in your fingers and then begins to dissolve them from the inside out (a painful process; amputation can be required).
Some common properties of acids are:
. They have a sour taste (tasting acids is not generally recommended!). For example, citric acid in lemons and vinegar are both sour.
. They can react with metals such as magnesium, zinc or iron to corrode them and produce explosive hydrogen gas. Do not store acids in metal containers!
. Solutions of acids can conduct electricity. Don't put acids near electrical outlets!
=== A basic solution is defined as one that has a pH greater than 7.0. Basic materials or solutions are sometimes called caustic or alkaline.
The following are examples of strong bases, meaning that they completely dissociate into ions and form OH- in aqueous (water) solution. For example NaOH -> Na+ + HO-.
All of these will cause severe burns upon skin contact :
Weak bases do not dissociate completely to form hydroxide (OH-) ions in water. Examples of these include ammonia (NH3), amines, fluoride ion (F-), and acetate ion (CH3COO-). Water can also act as a weak acid or base.
Here is a representative example of a chemical reaction of a weak base in water. The two arrows below are together called an equilibrium arrow, which means that the reaction takes place in both directions simultaneously until the concentration of each component reach a steady value :
NH3 + H2O <=> NH4+ + OH-
Just because a base is weak does not mean that it can't harm you. For example, ammonia can cause severe burning of the lungs and death if enough is inhaled and is extremely irritating to the eyes.
FIRE SAFETY and FIRE EXTINGUISHERS in a CHEMISTRY LABORATORY
All you must know about it.
FUMEHOOD SELECTION , PERFORMANCE , SAFETY
A very extensive Fumehood operation description.
GLASS : GROUND GLASS AND GLASSWARE CLEANING SAFETY
Ground glass is commonly used in laboratories. Any abrasion reduces the strength of glass, making it more susceptible to breakage under impact, pressure, and/or thermal shock. Thermal shock may result from sudden changes in temperature or use on a burner or hot plate. Serious injuries could result if breakage occurs while glass is pressurized or holds heated and/or corrosive liquid. To avoid accidents, follow these tips for safely using and cleaning glassware :
GLASS , TIPS :
· Borosilicate glassware is recommended for all laboratory glassware except for special experiments that use UV or other light sources.
· Careful handling and storage procedures should be used to avoid damaging glassware.
· Inspect the glassware before each use and discard if scratched on inner surfaces, chipped, cracked or damaged in any way.
· Use heavy gloves to protect the hands when inserting glass tubing into rubber stoppers/corks or when placing rubber tubing on glass hose connections. Tubing should be fire polished or rounded and lubricated, and hands should be held close together to limit movement of glass should fracture occur. The use of plastic or metal connectors should be considered.
· Glass-blowing operations should not be attempted unless proper annealing facilities are available.
· Vacuum jacketed glass apparatus should be handled with extreme care to prevent implosions. Equipment such as Dewar flasks should be taped or shielded. Only glassware designed for vacuum work should be used for that purpose.
· Tongs, a dust pan, and a broom are the best tools for cleaning up broken glass.
If hands are used to pick up glass, only handle large pieces of glass and wear heavy leather gloves to protect the hands. Broken glass must be packaged in labeled, rigid, and sealed containers before disposal in the trash. Take broken glass containers directly to the dumpsters.
Instruction manuals should be read in the use of glass equipment designed for specialized tasks, which can represent unusual risks for the first-time user.
· Use good glass cleaning techniques.
GLASS , Proper Cleaning Procedures
· Wear heavy, water-resistant rubber gloves during glassware cleaning operations.
Gloves with textured or slip-resistant palms are recommended. Also wear protective eyeware to prevent cleaning agents from entering the eyes.
· Washing machines may be used. Support racks on the washer must be well maintained. The support pins should be coated with a non-abrasive material to prevent metal to glass contact and scratching.
· For manual washing, use only plastic core brushes that have soft non-abrasive bristles or soft, clean sponges/rags. Use brushes to clean inside of deep glassware. Do not reach inside of glassware while cleaning to prevent cuts should the glassware break.
· Many commercial glass cleaners are available. Follow the manufacturer’s directions for the use of these products since some are corrosive and can damage the glass. Organic solvents are acceptable cleaning agents when conditions warrant their use.
· Do not use strong alkaline products and hydrofluoric acid as cleaning agents.
These materials dissolve glass, leading to damage and eventual breakage.
· Do not use any abrasive cleansers, including soft cleansers (e.g., Ajax, Comet, Old Dutch, Soft Scrub, etc.), as these will scratch the glass and cause eventual breakage and possible injury. Do not use abrasive cleaners. Scotch Brite and similar scouring pads will scratch glass and should not be used.
· Do not place metal or other hard objects, such as spatulas, glass stirring rods, or brushes with metal parts, inside the glassware. This will scratch the glass and cause eventual breakage and injury.
· Do not place hands inside glassware while wearing any jewelry, particularly diamond rings, as these will score the inside of the glassware and eventually cause breakage and injury.
· Do not use heat as a method to remove carbon residues. Heating glassware to temperatures >800°F will cause permanent stresses in the glass and eventual breakage.
· AVOID IMPACT - Glass will break as a result of impact. Use care when handling to avoid impacting hard objects, such as spigots, other glassware, counter tops, etc.
· Store glassware carefully during drying operations. Do not place round or oddly shaped glassware on countertops or other flat surfaces where they might roll off and break. Drying racks are the best option.
GLASS , Ground-Glass Surfaces
Ground-glass joints and stopcocks should never be used when dry. Although groundglass surfaces seal well without the use of lubricants, it is advisable to lubricate them to prevent sticking and breakage.
· Ground surfaces must be cleaned prior to lubrication—dust, dirt and particulate matter may score the surface and cause leakage.
· Different lubricants are used for these operating conditions:
Ш Silicone grease — for high temperature and high vacuum.
Ш Glycerin — for long term reflux or extraction.
Ш Hydrocarbon grease — for general laboratory use.
· Lubricate joints that must be airtight and when glassware contains strong alkaline solutions.
· Lubricate only the upper part of the inner joint. A properly lubricated joint appears clear, without striations.
· Spread two circular bands of grease around the stopcock plug. Insert the plug into the barrel and twist several times until the assembly is completely transparent. Be careful not to use too much lubricant or the bore will become plugged.
The actual heating element of any heating device should be enclosed in a glass, ceramic or metal case. Heating devices (a.k.a. heat sources include steam baths, water baths, oil and wax baths, salt and sand baths, heating mantles, and hot air or nitrogen baths) require autotransformers to control the temperature.
· Auto-transformers must be wired according to code and have a two-pole switch, a three-prong plug, and a power overload device. These devices are to be located away from areas where flammable vapors are produced.
· Unattended heating devices must be protected with overload circuitry and with a temperature-sensing device that will turn the power off in the event of overheating.
· When cooling water is used in connection with heating (as in the condenser of a solvent still), an automatic device to turn off the power when water flow is interrupted is absolutely necessary.
· When used with auto-transformers (variac or powerstat), make certain that the auto transformer is properly wired and located.
· The temperature of heating mantles can be effectively controlled with solid state controllers with a feedback sensor sensing the temperature of the heated liquid.
· If a solid state controller is used, make sure that the feedback device is fail-safe (i.e., if the circuit opens the power is turned off).
· Always support the heating mantle with a ring to allow air circulation around it to prevent overheating of the exterior of the mantel.
· Never support a heating mantle with combustible materials.
Hot Plates / Heated Stir Plates
· Hot plates with heating elements that are not totally enclosed must be discarded.
· Hot plates with temperature control devices must be spark-free.
· If water or other liquid has been spilled onto the element, have the equipment electrically checked before use.
· Allow plenty of time for the hot plate to cool before handling.
Personal Protective Equipment
· Use thermal gloves or tongs to remove items from their heating units.
· Use protective eyeware when using ovens, hot plates, or other heating devices.
HOUSEKEEPING IN LABS
Housekeeping is important in any work area. A clean, well maintained work area improves safety by preventing accidents and can enhance the overall efficiency of work in the space. Many of the housekeeping tips below are common sense. It is suggested a cleaning routine be established for the work area, with weekly pick-up, and thorough cleaning once a month.
· Keep the area as clean as the work allows. Work surfaces should be kept as clean as possible, with only those items needed for the immediate project on that surface.
· Clean all working surfaces at the end of each day.
· Keep floors clean and free of tripping hazards.
· Chemical products should be returned to their proper storing place after use.
· Clean up all small spills immediately. Know what to do in the event of a hazardous material spill and take appropriate action immediately.
· Do not let stored items project beyond the front of shelves or counter tops. Restrain material stored near entrances, when necessary, to prevent them from falling.
· Store items so they do not block access to your fire extinguisher(s), safety equipment,
electric panel boxes, or other emergency items such as an eyewash or safety shower.
· Do not allow combustible material such as paper, cardboard boxes, or pallets to accumulate. Do not place these materials in your hallway. Set up a process for immediate disposal or filing of items.
· Do not let materials accumulate. Ensure materials, chemicals, and equipment that are no longer needed, are disposed of properly or turned in as excess. Make sure you know how to manage laboratory wastes properly.
· Do not let materials accumulate in laboratory hoods. The safety of this workspace and the ventilation provided is compromised when excessive chemicals and equipment are kept in this space.
MERCURY , MERCURY SALTS SAFETY
Practical considerations when working with elemental mercury in the laboratory.
SEARCH keywords : mercury , Hg , Hg salt , toxic , practical , spill , clean up , thermometer , liquid , metal , reuse , recycling , dimethylmercury , lab , laboratory , environmental , precaution , procedure , element , poison , poisoning , health , safety .
Is there a medical test to show whether I've been exposed to mercury?
Tests are available to measure mercury levels in the body. Blood or urine samples are used to test for exposure to metallic mercury and to inorganic forms of mercury. Mercury in whole blood or in scalp hair is measured to determine exposure to methylmercury. Your doctor can take samples and send them to a testing laboratory.
Introduction and Background
Working With Mercury in the Laboratory
Recycling Mercury in the Laboratory
Risks and Environmental Impact
Introduction and Background
With proper controls and training, elemental mercury , Hg , can be safely used in a laboratory setting. However, when spilled or misused it can present a significant hazard; see Cleaning Up The Quicksilver Mess
( http://www.msta-mich.org/publications/newsletter/newsletter.september00/mercury.html ) for a chilling example. Therefore, minimize your use of mercury and mercury compounds whenever possible.
Small amounts of mercury residues left behind on contaminated glassware can be removed (dissolved) with a dilute nitric acid solution, HNO3. Be sure not to pour the acid waste down the sink. Collect the used acid solution in a waste container that is used only for mercury-contaminated nitric acid waste and dispose of it properly.
The element mercury is a liquid metal with a vapor pressure of 0.00185 mm at 25 degrees C. This corresponds to a saturation concentration in air of 20 milligrams of mercury per cubic meter of air or 2.4 ppm . The American Conference of Governmental Industrial Hygienists has established a threshold limit for mercury vapor of 0.05 milligrams of Hg per cubic meter of air for continuous 40 hour per week exposure. Long term chronic exposure to mercury vapor in excess of 0.05 mg Hg per cubic meter of air may result in cumulative poisoning. The use of mercury in laboratory amounts in well-ventilated areas is fairly safe; however, mercury can present a health hazard under the following circumstances:
. . . When a mercury spill is not cleaned up promptly it may be ground into the floor, fracturing into extremely small particles with a large total surface area (6.4 ft for 1 ml as 10 micron spheres). From such large areas mercury may vaporize at a rate faster than the room's ventilation can safely dilute it.
. . . The rate of mercury volatilization is directly related to temperature. Whenever elevated temperatures are involved special care must be exercised to provide adequate ventilation. A common occurrence is the breaking of thermometers in ovens due to bumping or raising the oven above the thermometer's capacity.
. . . The impact of mercury at high velocities or its release into high air velocity systems will atomize mercury into extremely small particle sizes and large surface area. This generally results from inadequate connections in pressure systems.
. . . Mercury is often dumped into drains. These drains may eventually leak and a workman using a torch to free the joints may, as the result of another's carelessness, receive an overexposure. [Such releases are also a violation of EPA regulations].
Mercury compounds can be quite dangerous. A professor at Dartmouth University (an experienced researcher and expert on the toxicology of heavy metal poisoning) died in 1997 after spilling just a few drops of dimethylmercury on her latex gloves ( http://www.denison.edu/naosmm/topics/dartmouth.html ).
In case of underground chemists, the chance to ever work with methyl or dimethylmercury is neglectible small.
Working With Mercury in the Laboratory
Whenever you perform any action with mercury it will spill and splash. It inevitably forms tiny beads that cling to many surfaces and roll several feet away. Large drops quickly break up into thousands of small ones as described above.
Mercury can be handled safely by a professional chemist, although you should minimize or eliminate its use whenever possible. Here are some prudent practices when using mercury:
1. Find an alternative to using mercury in the first place:
a. Use alcohol thermometers instead of mercury ones.
b. Use oil bubblers instead of mercury bubblers when possible.
c. Consider using reducing agents other than mercury amalgams in your laboratory procedures.
2. NEVER use a mercury thermometer in a laboratory oven. If it breaks in a hot oven, you have not only the obvious health concern, but also a possible unavoidable HazMat response situation. You'll have to shut down your lab completely, probably for several days, for cleaning and testing. The oven will have to be disposed of as hazardous waste. A break in a cold oven is an equally serious situation.
The cost of cleaning up a thermometer break in a laboratory oven far exceeds that of a new laboratory oven with a built-in digital temperature display and fail-safe mechanism.
3. Do not leave open containers of mercury in the laboratory. If used in a bubbler, the exhaust should go up a vertical tube to eliminate splashing and should be vented to a fume hood.
4. Do not keep excess mercury around if you do not need it.
5. Clean up spills promptly. When handling mercury use a glass, plastic or steel tray to contain any spills that might occur. Caution: mercury amalgamates with many common metals such as aluminum, so choose your container carefully.
6. Glass or plastic vessels should have a secondary steel or plastic container around them in case the vessel fails.
7. Do not use mercury where it could contact a hot surface and vaporize.
8. Avoid inhaling mercury vapor and use suitable gloves when working with it.
9. Put mercury waste in a special waste container. Do not combine it with "regular" organic or inorganic wastes. NEVER dispose of it down the sink!
10. Do not wear gold or silver jewelry when working with mercury; it will amalgamate and irreversibly damage your jewelry!
11. Although not a safety issue, mercury is very expensive to dispose of as waste.
12. Take appropriate measures in the event of a spill. Sprinkling elemental sulfur on spilled mercury is virtually ineffective; the reaction between Hg and S is not appreciable at room temperature. Amalgamation with fresh zinc dust works fairly well for "soaking up" those noisome tiny beads of mercury once the bulk of the spill has been collected manually.
13. Read the Material Safety Data Sheet (MSDS) for mercury before using it. As indicated on the MSDS, mercury is dangerously incompatible with aluminum, ammonia, chlorates, copper, copper alloys, ethylene oxide, halogens, iron, nitrates, sulfur, sulfuric acid, oxygen, acetylene, lithium, rubidium, sodium carbide, lead, nitromethane, peroxyformic acid, calcium, chlorine dioxide, metal oxides, azides, 3-bromopropyne, alkynes + silver perchlorate, methylsilane + oxygen, tetracarbonylnickel + oxygen and boron diiodophosphide.
14. As with most other chemicals in your laboratory, access to mercury should be restricted to a locked cabinet or room. Do not leave mercury where a passerby or unauthorized person can swipe it (see the Quicksilver Mess article above).
Recycling Mercury in the Laboratory
Those who use mercury know that clean mercury has a wonderfully shiny surface. But over time, the mercury in your bubbler or diffusion pump tends to get dirty and contaminated, usually with a floating film of gray/black sludge. While you certainly need to clean your apparatus, you can easily recover most of the mercury for reuse rather than replacing it. This saves on disposal costs and reduces the amount of mercury you need to use.
The "best" cleanup method in a chemical sense would be distillation However, boiling mercury and then cleaning up the distillation apparatus afterward is not appealing for a number of obvious reasons. Luckily, there are two easier methods that work quite well for most needs. Before using either of these, set up a large steel or plastic spill tray in a fume hood! Do not try this on the bench because you will spill some mercury :
1. The syringe technique. Get a 10 mL syringe with needle. Stick the needle below the surface of the contaminated mercury and withdraw clean mercury. Hold onto the syringe with both hands when you withdraw it, keeping the syringe vertical and holding the plunger to prevent/reduce mercury from dribbling back out. Transfer the mercury to your recovery vessel (which should be only an inch or two away).
2. The filter paper technique. Fold a filter paper into quarters and then rip a tiny hole in the bottom of the cone. Place the paper in a glass or plastic funnel with the stem of the funnel as close to the bottom of your collection vessel as possible (to minimize splashing). Slowly pour your contaminated mercury into the filter. Most of the sludge will remain behind on the filter paper. You may need to refilter one or more times.
Clean mercury has a mirror-like surface. These cleanup methods work because the sludge is insoluble and less dense than mercury. If your mercury is contaminated with a metal that has amalgamated such as sodium, you may be able to remove the metal chemically, for example, by quenching the sodium metal using established procedures. If the metal is not easily or safely removable through such chemical means, then proper disposal (rather than dealing with distillation) is your best option.
Small amounts of mercury residues left behind on contaminated glassware can be removed (dissolved) with a dilute nitric acid solution. Be sure not to pour the acid waste down the sink. Collect the used acid solution a waste container that is used only for mercury-contaminated nitric acid waste and dispose of it properly.
Risks and Environmental Impact
Remember, inhalation is the primary danger from mercury, especially if there is no good ventilation.
Brief, one-time exposures on the skin (from handling mercury) or even ingestion (it has been used as a laxative) are not likely to produce significant health effects in most cases, but don't test your luck. Chronic (long-term) exposure of any sort can lead to all sorts of nasty effects including permanent central nervous system damage, fatigue, weight loss, tremors, personality changes and death.
Because of the ease with which mercury is spilled, the difficulty of ensuring complete cleanup, the curiousity factor of a room temperature liquid metal, and the known health risks, it is recommended that mercury use for fresh Newbees be discontinued entirely. This includes both mercury-containing compounds as well as equipment such as thermometers.
ATSDR has a Public Health Statement ( http://atsdr1.atsdr.cdc.gov/ToxProfiles/phs8916.html THE MOST EXTENSIVE MERCURY FACTS SOURCE THERE IS !!!) as well as a Toxin FAQ ( http://atsdr1.atsdr.cdc.gov/tfacts46.html ) on mercury.
Mercury In Schools ( http://www.mercuryinschools.uwex.edu/ ) is an excellent site with lots of additional information.
UNL has a page briefly detailing how to handle mercury spills in the laboratory ( http://bifrost.unl.edu/ehs/FactSheets/mercmetl.html ).
Search the SIRI MSDS database or check for an MSDS direct from the manufacturers lists, or, if you need chemical toxicity data , you can search Toxicology Reports here as well (These are NOT MSDSs), you can also search via CAS numbers you can find in chemicals catalogues :
SIRI MSDS Index :
MSDS Translation and MSDSs in languages other than English :
3DWord , http://www.3dword.com/msds.htm MSDS translation to all major languages
Racco Safety , http://www.raccosafety.com.br/ (Brazil) MSDS in Spanish and Portugese
Dell Tech- MSDS Authoring in English, French and Spanish , http://www.delltech.com/
Pro-Active Translations , http://hazard.com/msds/www.biomedtranslation.com
MSDS-Mexico , http://www.msds-mexico.com/ Automatic or manual creation of MSDS in Spanish
Harris , http://www.harrisind.com/spcat.htm Safety warnings and signs in Spanish
MSDS and Safety information in Italian , http://www.eidos.it/
Internet Resources for MSDS :
Scroll down !!!
We should restrict ourselfs at the HIVE to IUPAC or/and CAS nomenclature.
And include those nrs in important procedures, for the precursors and endproducts.
There must be one Hive-guideline for nomenclature we must follow to indicate chemicals :
The HTML version of IUPAC "Blue Book" Nomenclature of Organic Chemistry, Pergamon
Press, Oxford, 1979 and A Guide to IUPAC Nomenclature of Organic Compounds.
Description: Recommendations 1979 and 1993. Nicely organized and searchable.
Basic Organic Nomenclature, An Introduction.
Dave Woodcock ©1996,2000 Okanagan University College.
http://www.chem.qmul.ac.uk/iupac/ UP to DATE! IUPAC Chemical Nomenclature Searchable:
IUPAC International Union of Pure and Applied Chemistry :
USA : http://www.iupac.org/
: http://www.iupac.org/general/index.html : Search IUPAC.
GERMANY : http://sunsite.informatik.rwth-aachen.de/iupac/
UK : http://iupac.chemsoc.org/
Systematized Nomenclature of Medicine, better known as SNOMED® :
Released in January 2002. SNOMED users include many leading organizations in the health care industry and health information technology field, from nationwide provider organizations and HMOs to pharmaceutical companies, Web portals and government agencies.
CAS, Chemical Abstracts Service HomePage :
http://www.cas.org/ World's largest and most comprehensive chemical database with over 21 million document records.
The CAS Substance Databases:
* help you identify over 21 million organic and inorganic substances and 29 million sequences, each with a unique CAS Registry Number
* locate your substance as either a reactant or product in a reaction
* ensure a complete search of the prior art for your proposed patent
* assure that the substances you use in manufacturing are within regulatory compliance
= Regulated Chemicals Information: http://www.cas.org/Support/substance.html , read, then go to:
+ http://www.cas.org/CASFILES/chemlist.html CHEMLIST contains national inventory information from Australia, Canada, Europe, Israel, Japan, Korea, Philippines, Switzerland, Taiwan, and the United States. These are NOT the CONTROLLED Substances lists!
* verify that the substance is available from a supplier
* Check the Substance Counter for the most up to date numbers.
Where can I find CAS REGISTRY Numbers? Find CAS Registry Numbers in online databases :
http://www.cas.org/stn.html CAS Search
You can use STN with confidence because the system and the more than 200 databases :
( http://www.cas.org/ONLINE/DBSS/dbsslist.html ) it brings you are operated by some of the most respected scientific organizations in the world.
University of Minnesota:
Chem Lab Safety Plan (Added 04-08-04):
An excellent text with many informative data sheets and appendices on lab and chemical safety.
SEARCH keywords : Ultrasonication , ultrasonicator , liquid , ether , sound waves , hearing protection , ultrasonic equipment , infectious agents , lab , laboratory , precaution , procedure , health , safety .
Ultrasonication uses sound waves to agitate mixtures. This process can cause rapid heating, localized points of high temperatures and pressures, and sound waves that could exceed NIOSH hearing protection levels. Follow these safety tips for preventing accidents and for hearing comfort when using ultrasonicators.
· Never use ultrasonication for sealed flasks or with flammable liquids, especially low-boiling solvents, such as ether.
· Ultrasonic equipment in the lab can be enclosed in a box lined with acoustically absorbing materials to reduce (mostly inaudible) emissions. Noise reducing boxes can be purchased from various vendors. Many come with clear acrylic doors that permit safe viewing of samples during processing. If your ultrasonic equipment cannot be enclosed, workers should wear earmuffs or other hearing protection for their comfort.
· Do not use sonicators with infectious agents.