Chemical Safety

Chemical safety means personal safety

Chemical Storage Guidelines

Storing chemicals requires some thought and common sense. Many accidents that result from chemicals are caused by people being unfamiliar with storage procedures or being carelessly negligent. Observe these guidelines for storage after you receive chemicals:

Move chemicals immediately to a designated storage area. Place large glass containers in carrying containers or shipping containers during transportation. Pack carefully

Separate chemicals by hazard classification and compatibility in a well identified area, with adequate local ventilation

Separate mineral acids from flammable and combustible materials. Separation of stored chemicals is defined by the NFPA as stored within the same fire area but separated by as much space as practicable or intervened by storage of incompatible materials

Place acid-resistant trays shall under bottles of mineral acids Separate, and keep from contact with acids, acid-sensitive materials such as cyanides

and sulfides Store highly toxic chemicals or other chemicals whose containers have been opened

in unbreakable secondary containers Place chemicals in an outer container or bucket when taken from the storage area Make sure that all chemicals are properly labeled before they are put in storage.

NOTE

Don't store flammables in unapproved refrigerators.

Storing chemicals at the lab bench

Limit storage of chemicals at the lab bench or other work areas to those amounts necessary for one operation or shift. The container size shall be the minimum convenient. The amounts of chemicals at the lab bench shall be as small as practical. Do not expose chemicals in the workplace to sunlight or heat.

NOTE

Do not use the storage area as a preparation or repackaging station. Transportation Transportation of chemicals presents a potential danger to you or to other workers, and that danger can extend to the general public. Observe these guidelines for transporting chemicals:

DON’T Transport any chemical if you are unsure about its stability, integrity, or behavior Transport hazardous wastes yourself Transport chemicals during busy times, such as during a change of classes. DO Place chemicals in a safety container such as an acid-carrying bucket to protect

against breaks and spills Make sure your transport is stable and safety is observed: If you are transporting chemicals on a wheeled cart, the cart should have wheels large

enough to go over uneven surfaces without suddenly tipping or stopping If you must use a passenger elevator, label the chemicals and carry them in safety

containers

Fill out a Hazardous Chemical Transport Manifest for all chemicals either classified as hazardous waste or suspected to be hazardous waste

Turn in the Manifest to EH&S for evaluation, transport, and disposal.

Inspection and inventory

Lab managers must examine stored chemicals regularly for replacement, deterioration, and container integrity. The inspection can determine whether any corrosion, deterioration, or damage has occurred to the storage facility as a result of leaking chemicals.

In addition to inspections by the Lab Manager, the Chemical Safety Officer conducts periodic inventories of chemicals in campus labs and stockrooms.

Chemicals With Specific Properties

The guidelines listed below cover handling procedures and safety precautions for chemicals with specific properties.

Flammable liquids

WARNING

Never smoke near flammable liquids!

Never use an open flame near flammable liquids!

Flammable liquids are the most common of hazardous substances found in the laboratory. The ability of a liquid to vaporize, ignite, burn, or explode varies depending on its flash point. A flash point is the temperature at which a liquid gives off vapor in sufficient concentration to form an ignitable mixture with air. The solvent will not ignite below nor above the flash point.

When flammable materials are being used in a laboratory, close attention should be given to all potential sources of ignition. The vapors of all flammable liquids are heavier than air and capable of traveling considerable distances. Take special note that the ignition sources of flammable materials are usually closer to the ground than the level at which the flammable substance is used.

Observe these guidelines when handling flammable liquids:

Handle flammable liquids only in areas free of ignition sources Place and observe No Smoking signs wherever flammable liquids are handled or

stored Dispense and use flammable liquids in a hood or well-ventilated area so that

flammable vapors will not accumulate Substitute nonflammable liquids whenever possible Use some other type of heat source, such as a steam bath or water bath, instead of an

electrical heat source or open flame.

NOTE

Transfer flammable liquids carefully. The friction of flowing liquids may be sufficient to generate static electricity which in turn can cause a spark and ignition. Therefore, ground or bond all such large containers before pouring from them.

Flash point information

Flash point information is usually available on the label attached to the chemical container, on the MSDS, or in tables. Flammable liquids are those with flash points below 37.7ºC (100º F). Combustible liquids have flash points between 37.7 and 93.3ºC (100 and 210ºF).

Among the most hazardous liquids are those that have flash points at room temperature or lower, particularly if their range of flammability is broad. For a fire to occur, three conditions must exist:

A concentration of flammable vapor that is within the flammable limits of the substance

An oxidizing atmosphere such as common air A source of ignition, such as paper.

Elimination of one of these three will prevent the start of fire or extinguish an existing fire. See Table 1 on the next page for a list of flammable liquids with flash points below 100ºC (37.7ºF).

Table 1: Flammability data of common laboratory solvents

CHEMICAL CLASS FLASH POINT

BOILING POINT

IGNITION TEMPERATURE

FLAMMABLE LIMITS [by volume in air]

ºC ºC ºC LOWER UPPERAcetaldehyde 1A -37.8º 21.1º 175.0º 4.0 % 60.0 %Acetone 1B -17.8º 56.7º 465.0º 2.6 % 12.8 %Benzene 1B -11.1º 80.0º 560.0º 1.3 % 7.1 %Carbon Disulfide 1B -30.0º 46.1º 80.0º 1.3 % 50.0 %

Cyclohexane 1B -20.0º 81.7º 245.0º 1.3 % 8.0 %Diethyl Ether 1A -45.0º 35.0º 160.0º 1.9 % 36.0 %Ethyl Alcohol 1B 12.8º 78.3º 365.0º 3.3 % 19.0 %h-Heptane 1B - 3.9º 98.3º 215.0º 1.05 % 6.7 %h-Hexane 1B -21.7º 68.9º 225.0º 1.1 % 7.5 %Isopropyl Alcohol 1B 11.7º 82.8º 398.9º 2.0 % 12.0 %

Methyl Alcohol 1B 11.1º 64.9º 385.0º 6.7 % 36.0 %

Methyl Ethyl Ketone 1B - 6.1º 80.0º 515.6º 1.8 % 10.0 %

Pentane 1A -40.0º 36.1º 260.0º 1.5 % 7.8 %Styrene 1B 32.2º 146.1º 490.0º 1.1 % 6.1 %Toluene 1B 4.4º 110.6º 480.0º 1.2 % 7.1 %p-Xylene 1C 27.2º 138.3º 530.0º 1.1 % 7.0 %

Storage of flammable liquids

The following guidelines should be observed in the storage of flammable liquids:

Store flammable liquids to comply with those requirements specified in NFPA Standard #30: "Flammable Liquids"

Keep only small quantities of flammable liquids available for immediate use Use explosion-safe refrigerators and cooling equipment for storing certain reactive or

highly-flammable liquids. Explosion-safe equipment is externally wired to remove

possible internal sources of ignition. See Chapter 4: Safety Equipment for more information on explosion-proof refrigerators

Use NFPA-approved flammable-liquid storage cabinets when flammable liquids need to be stored in the laboratory.

The NFPA standard for flammable liquids is shown in Tables 2 and 3 on the next page.

NOTE

An ordinary five-gallon container does not provide adequate protection in cases of fire.

An approved safety can with a self-closing cover, vent, and flame arrester is the best container for storing flammable liquids or waste solvents in small quantities.

Table 2: Flammable liquids -- maximum size of containers

CONTAINER TYPE CLASS 1A LIQUIDS

CLASS 1B LIQUIDS

CLASS 1C LIQUIDS

Glass (see Note below) 1 pint 1 quart 1 gallonApproved Metal or Plastic 1 gallon 5 gallons 5 gallonsSafety Cans 2 gallons 5 gallons 5 gallonsMetal Drums (ICC Specifications) 60 gallons 60 gallons 60 gallonsClass 1A -- Flash point below 73 F. Boiling point below 100 F. Class 1B -- Flash point below 73 F. Boiling point at or above 100 F. Class 1C -- Flash point at or above 73 F, and below 100 F.

NOTE Exceptions may be made to regulations for glass for storage of Class 1A and Class 1B liquids up to 1 gallon, but you must ask EH&S for permission first.

Table 3: Flammable liquids -- maximum quantities

LOCATION MAXIMUM AMOUNT CONDITIONS

In the laboratory 10 gallons Observe the flash points and boiling points shown in Table 2 above.

In safety cans in the laboratory 25 gallons Observe the flash points and boiling points

shown in Table 2 above.In a fire-rated storage cabinet 50 gallons No conditions specified.

Toxic materials

Before you start work with a chemical substance, you (the researcher or laboratory person) should be familiar with certain aspects of the chemical, particularly:

The types of toxicity of the chemical The toxic dose of the chemical The hazards of the chemical.

Also realize that two or more substances may act synergistically -- that is, the combination of the substances can produce a toxic effect greater than that of either substance alone.

Toxicity is the capability of a chemical to induce injury in a body. Almost any substance is toxic when taken in doses exceeding tolerable limits.

Hazard is the probability that an injury will occur or the chance that a person will be exposed to a toxic dose.

The effects of a toxic chemical may be sorted into several categories:

Local toxicity is the effect a substance has on the body tissues on the point of contact Systemic toxicity is the effect a substance has on the body tissues other then on the

point of contact Acute toxicity is the effect a substance has after only a few short, relatively large

exposures Chronic toxicity is the effect a substance has as a result of many small exposures

over a long period of time.

Examples of toxic materials are:

Acrolein Allyl alcohol Metal cyanides Strong bases and acids Phenols Phosgene Nitrobenzene Toulene-diisocyanate.

A person can be exposed to a chemical substance through a number of different routes:

Inhalation Ingestion Contact with skin or eyes.

Inhalation

Inhalation of toxic vapors, mists, gases, or dusts can result in poisoning by absorption through the mucous membranes of the mouth, throat, and lungs and can cause serious effects. Lungs have a large surface area: a total surface area of 90 square meters. This large surface area, along with continuous blood flow, will rapidly absorb inhaled gases or vapors and carry them into the circulatory system.

The rate of absorption will vary with the concentration of the toxic substance, its solubility, and the individual inhalation rate. The degree of injury from exposure to a toxic substance depends on the toxicity of the material, its solubility in tissue fluids, and the concentration and duration of exposure.

Table 4: Combined tabulation of toxicity classes

COMMONLY USED TERM LAB TESTS

COMPARATIVE LETHAL DOSE LEVELS FOR HUMANS

LD50 SINGLE ORAL DOSE FOR RATS

4-HOUR VAPOR EXPOSURE CAUSING 2-4 DEATHS IN 6-RAT GROUPS

LD50 EXPOSURE ON THE SKIN FOR RABBITS

SINGLE ORAL

LD50 EXPOSURE ON

DOSE FOR RATS THE SKIN

grams per kilogram (g/kg)

parts per million (ppm)

grams per kilogram (g/kg)

Extremely toxic 0.001 or less 10.0 or less 0.005 or less Taste (1 grain)Highly toxic 0.001 - 0.05 10.0 - 100.0 0.005 - 0.043 1 teaspoon (4 cc)Moderately toxic 0.05 - 0.5 100.0 - 1,000.0 0.044 - 0.340 1 ounce (30 grams)

Slightly toxic 0.5 - 5.0 1,000.0 - 10,000.0 0.35 - 2.81 1 pint (250 grams)Practically nontoxic 5.0 - 15.0 10,000.0 - 100,000.0 2.82 - 22.6 1 quart

Relatively harmless

15.00 or more 100,000.0 or more 22.6 or more 1 quart or more

Ingestion

Ingestion of chemicals used in the laboratory can result in significant bodily injury. The relative acute toxicity of a chemical can be determined by its oral Lethal Dose 50% (oral LD50). An oral LD50 is the quantity of material ingested that will cause 50% of test animal deaths. Oral LD50 is usually expressed in milligrams per kilogram of body weight (mg/ kg body weight).

To prevent ingestion of chemicals:

Wash your hands immediately after using any toxic substance and before leaving the laboratory

Do not store or consume food, drink, or tobacco in areas where chemicals are being used

Most importantly, chemicals must never be tasted.

Contact with skin or eyes

Two other ways of ingestion are through contact with skin or eyes.

Skin contact. Skin contact is the most frequent route of exposure to chemical substances. A common result of skin contact is local irritation. But, some materials can be absorbed sufficiently through the skin to cause systemic poisoning.

To protect against skin contact with chemicals, use gloves, laboratory coats, tongs, and other protective devices. Consult chemical resistance charts for determining what types of clothing and materials resist the corrosive actions of specific chemicals.

Eye contact. Eye contact with most chemicals will result in pain and irritation. The vascular network of the eyes permits rapid absorption of many chemicals. And, a considerable number of chemical substances are capable of causing burns or vision loss. Alkaline substances are particularly corrosive and can cause permanent vision loss.

To prevent eye contact with chemicals, you should always wear safety glasses in the laboratory. For even better protection than safety glasses, use face shields, body shields, or safety goggles.

With these aspects in mind, be sure to thoroughly check your experimental procedure before you begin

Particularly dangerous acids

Certain acids are particularly dangerous in concentrated form:

Nitric acid Perchloric acid Picric acid Hydrofluoric acid.

Nitric acid

Nitric acid is a corrosive, flammable oxidizer. It can produce flammable and explosive compounds with many materials: ethers, acetone, and other combustible materials. Paper used to soak up nitric acid may ignite spontaneously when dry. Use nitric acid in a hood only. Store nitric acid away from combustible materials.

Perchloric acid

WARNING

Do not keep perchloric acid for more than one year. Explosive crystals can form in the acid.

Perchloric acid forms highly explosive, unstable compounds with many organic compounds and with metals. Unstable perchlorate compounds can collect in the duct work of fume hoods and cause fire or violent explosions.

Observe these guidelines when using perchloric acid:

Label and date perchloric acid when it is initially received Use perchloric acid with extreme caution and with a special fume hood designed for

its use. A perchloric acid hood has corrosion-resistant ducts and chemical washdown facilities

Keep only a small container of perchloric acid if needed for the present experiment Store the container in the perchloric acid hood on a glass tray deep enough to hold the

contents of the bottle.

Picric acid

Picric acid can form explosive compounds with many combustible materials. When the moisture content decreases, picric acid can become unstable and can explode from being shaken also. Date the container of picric acid and store it away from combustible materials. Do not store picric acid for more than one year.

Hydrofluoric acid (HF)

Hydrofluoric acid (HF) is extremely corrosive and can even attack glass. All forms -- diluted or concentrated solutions of the vapor -- can cause serious burns. Inhalation of hydrofluoric acid mists or vapors can cause you to suffer serious respiratory tract irritation which can be fatal. Burns from hydrofluoric acid heal slowly and with great difficulty.

NOTE

Hydrofluoric acid must always be used in a suitable, functioning fume hood.

Use gloves, eye protection, and a lab coat when handling the acid.

Take care to avoid contacting hydrofluoric acid with metals or ammonia. Toxic fumes can result from this contact.

Always store hydrofluoric acid in the original, Teflon-lined containers in which it was purchased.

Peroxides and peroxide-forming substances

In general, peroxides are among the most hazardous of substances handled in the laboratory. Organic peroxides are particularly sensitive and unstable. They are a class of compounds that have unusual stability problems. This instability makes them among the most hazardous substances handled in laboratories.

As a class, organic peroxides are considered to be powerful explosives. They are sensitive to heat, friction, impact, and exposure to light. In addition, organic peroxides are sensitive to strong oxidizing and reducing agents. All organic peroxides are flammable. Examples of organic peroxides are:

Acetyl and benzoyl hydroperoxides Di-t-butyl peroxide Alkyl and aryl hydroperoxides.

In addition, certain substances can form peroxides over time. See Table 5 on Page 85 for a list of compounds known to form peroxides. See Table 6 on Page 86 for specific chemicals that can form dangerous concentrations of peroxides.

Observe these safety guidelines when using peroxides:

Do not store peroxides -- especially peroxide-forming substances such as ethers -- in ground, glass-stoppered bottles

Use metal cans to store peroxides Store all peroxides and peroxide-forming materials in a cool place, away from light

Order ethers and other peroxide-forming substances in small quantities Order ethers and peroxide-forming compounds which are relatively stable. For

example, order tert-butyl ether instead of ethyl ether Date peroxides and peroxide-forming substances: Upon receipt When packages are opened Discard peroxides and peroxide-forming substances: Unopened: within a year after receipt Opened: within six months after opening package. Always handle ethers in a hood to assure proper ventilation. Using the hood can

protect individuals from inhaling the vapors and can prevent explosive concentrations of the vapor from accumulating.

Table 5: Common compounds that form peroxides during storage

Acetal Methyl acetyleneButadiene MethylcyclopentaneChlorobutadiene (Chloroprene) Methyl i-butyl ketoneChlorotrifluoroethylene Potassium metalCumene Sodium amideCyclohexene StyreneDiacetylene Tetrafluoroethylene

Dicyclopentadiene TetrahydrofuranDioxane TetrahydronaphthaleneDivinyl acetylene Vinyl acetateEthyl ether Vinyl acetyleneEthylene glycol dimethyl ether Vinyl chloride(glyme) Vinyl pyridineIsopropyl ether Vinylidene chloride

Table 6: Peroxide-forming structures

Structures Structure Related Examples

1 Ethers and acetals.

2 Olefins with allylic hydrogen, chloroolefins and fluoroolefins, terpenes, and tetrahydronaphi-thalene.3 Dienes and vinyl acetylene.4 Vinyl Monomers.5 N/A 1 Potassium.6 N/A 1 Alkali metal alkoxides and amides, and sodamide.7 Paraffinic and alkylaromatic hydrocarbons, particularly those with tertiary hydrogen.8 N/A 1 Grignard reagent.9 Aldehydes and ketones. NOTE Anhydrous acetaldehyde with ultraviolet-light catalysis forms peracetic acid. This combination will chain-react with more acetaldehyde to produce the explosive acetaldehyde monoperacetate.1 N/A: Structure not available.C = Carbon / H = Hydrogen / O = Oxygen

Corrosives

Corrosives consist of four major classes:

Strong acids Strong bases Dehydrating agents Oxidizing agents.

Each of these classes of corrosives can erode the skin, tissue and mucous membranes. Corrosives are especially damaging to the eyes.

Storage and use of corrosives

WARNING

When mixing or diluting solutions, do not pour water into acids. The correct procedure is:

Pour acids -- slowly -- into water.

In storing and using corrosives, observe these guidelines:

Store acids and alkalis:

In a cool-ventilated area Away from each other and from metals, flammables, and oxidizing material Check the storage area regularly for spills and leaks. Be sure suitable spill cleanup

materials are available Cap bottles and store them securely Clean up spills promptly. Do not leave residue on a bottle or lab bench where a person

may come into contact with it Wear protective clothing when handling acids or alkalis. Protective clothing includes rubber gloves, eye protection devices, and aprons.

Oxidizing agents and reactives

Highly-reactive chemicals and explosives require special care. Certain chemical reactions are considered safe because the reaction rate is either relatively slow or can be easily controlled. However, certain reactions proceed at such a fast rate and generate so much heat that, if left uncontrolled, they result in explosion. Oxidizing agents present fire and explosion hazards on contact with organic compounds and other oxidizable substances.

Reactives are unstable materials that:

Explode React with water violently Form explosive mixtures Generate dangerous quantities of toxic gases such as hydrogen sulfide and hydrogen

cyanide with water at any pH.

Examples of oxidizing agents and reactives are:

Inorganic nitrates Permanganates Chromates and hypochlorite salts Concentrated organic and inorganic peroxides Chromium trioxide Cyanide or sulfide-containing material Commercial explosives Organic peroxides Titanium tetrachloride Alkali metals.

When dealing with highly reactive chemicals and explosives:

Provide a large surface area for heat exchange to allow sufficient cooling Consult the laboratory supervisor or principal investigator when planning an

experiment in which reactives are used or hazardous conditions may occur.

Storage and use of oxidizing agents

In the storage and use of oxidizing agents, observe these guidelines:

Store oxidizing agents separately from flammable liquids, organics, dehydrating agents, and reducing agents

Store and use inert containers such as glass for particularly strong oxidizing agents. Do not use rubber or cork stoppers

Use caution when handling oxidizing agents in the vicinity of flammable materials.

Dehydrating agents

Dehydrating agents include:

Concentrated sulfuric acid Sodium hydroxide Phosphorous pentoxide Calcium oxide.

In order to avoid violent reactions and splattering, always add these chemicals to water -- never the reverse. Dehydrating agents can cause severe burns on contact with skin.

Storage and use of dehydrating agents

Always store dehydrating agents in a corrosion-resistant cabinet in a cool dry place.

Organic metals

Organic metals are divided into two classes:

Alkali metals Metal powders.

Alkali metals

WARNING

Use only special, Class D, dry powder fire extinguishers specifically designed for alkali metals on alkali metal fires.

Alkali metals such as sodium and potassium react violently with water. The metal decomposes the water back into oxygen and hydrogen. The hydrogen can ignite from the heat of the reaction.

Also, alkali metals can ignite spontaneously in air, especially if one or both of these conditions are present:

The metal is in powdered form The air is moist.

Storage and use of alkali metals. In using and storing alkali metals, observe these guidelines:

Store alkali metals under mineral oil or kerosene. Avoid using oils containing sulfur since a hazardous reaction can occur

Use care when disposing alkali metal waste:

Place alkali metal waste in a labeled, leak-proof container

Cover with mineral oil

Contact EH&S for waste pickup service.

Metal powders

Metal powders are as the name implies: finely ground metal in a powdered form. Metal powders can create certain hazards:

They can come into contact with acids, then ignite and burn They can create a dust explosion hazard. In a common scenario, the powder becomes

airborne in an area where a spark or flame is present. Then the powder oxidizes, ignites, and explodes

They can be highly toxic. Take precautions against inhalation of fine metal powders.

Storage and use of metal powders. To protect against exposure to metal powders, especially through inhalation, construct a clean-room environment with special ventilation or a controlled-atmosphere glove box. Contact your Lab Manager for inquiries.

Cryogenics

Cryogenics are materials that are supercooled. Cryogenic materials have certain hazards:

Cryogenics can cause serious burns on skin Cryogenics in containers stored in unvented spaces can build up pressure Cryogenics can cause fire, explosion, or asphyxiation if improperly or accidentally

evaporated.

Storage and use of cryogenics

Observe these guidelines for storing and using cryogenics:

Wear eye protection whenever you handle cryogenic liquids Use face shields if splashing is a possibility Wear appropriate gloves, shoes, and clothing. See Section 4.4: Protective Equipment

and Clothing Flood exposed areas and clothing with water in case of a splash Avoid wearing watches, rings, bracelets, or other jewelry when handling cryogenics Provide plenty of ventilation to avoid asphyxiation from cryogenics Provide safety venting to anticipate quick, violent pressure changes in cryofluid Handle combustible cryogenics such as liquid hydrogen and liquid natural gas in the

same manner for combustible gases: Provide ventilation Keep cryogenics away from open flames and other ignition sources Prohibit smoking Vent gases to a safe location Tape exposed glass portions of a cryogenic container. Securing the glass will reduce

the possibility of flying glass if the container should explode.

Compressed-gas cylinders

Observe the following rules when using compressed-gas cylinders:

Never attempt to refill cylinders Don't transport cylinders by carrying by hand or dragging them. Transport cylinders

with a hand truck Don't use cylinders without a pressure regulator Don't rely on a regulator to stop overnight gas flow of cylinders. Close valves when

cylinders are not in use Label all gas cylinders to identify their contents Know the properties of the chemical contents of gas cylinders Handle gas cylinders carefully Store and use gas cylinders in well-ventilated areas Keep away from heat and ignition sources

Keep oxygen cylinders away from flammable gas Keep reactive gases separate Chain or strap in place cylinders to prevent them from falling over Keep metal caps on at all times when the cylinders are not in use Close valves on empty cylinders and mark the cylinder EMPTY.

NOTE

Do not use color codes to label cylinders. Colors can cause confusion, especially to someone who is color-blind. Radioactive materials Radioactive materials are liquids and solids that spontaneously emit Alpha, Beta, or Gamma radiation. Radioactive materials require special lab procedures and laboratory supervision.

Radiation, both in natural form and from laboratory chemicals (radioisotopes), can cause a variety of adverse health effects in humans and living animals. When handling radioactives, you must always work under the supervision of a competently-trained person registered with EH&S. Consult the EH&S Radiation Safety Workbook or the Radiation Training Guidebook for further information.

NOTE

Consult EH&S if you need to work with radioactive materials. Biological Hazards Certain laboratory materials can be hazardous by being a biological hazard, an infectious disease hazard, or an etiological agent. These hazards require special equipment, laboratory procedures, and waste procedures.

Examples: chronic toxins, embryo-tetrotoxins, and etiological agents. Etiological agents are a variable micro-organism or its toxin which causes human disease.

NOTE

Please consult the EH&S Biological Safety Guidebook for information and for more detailed biological safety measures than described here.

OSHA's Bloodborne Pathogens Standard requires all laboratories handling biologically-hazardous chemicals to have an exposure control plan specific to these hazards. Other Hazardous Materials Hazardous materials, as discussed in the previous sections of this chapter, are defined as:

Any chemical or material that is flammable, corrosive, toxic, or reactive.

This section covers specific hazardous materials not covered previously in the manual.

Incompatible hazardous materials

Certain combinations of chemicals are particularly dangerous and should be avoided. The properties of hazardous materials determine what precautions to take for individual chemicals. See Table 7 beginning on the next page for a quick review of incompatible chemicals. Use this table when planning storage arrangements. Also, use this table to avoid storing incompatible chemicals together.

Table 7: Incompatible Chemicals

# CHEMICAL INCOMPATIBLES

1 Acetic acid Chromic acid, nitric acid, hydroxyl compounds, ethylene glycol, perchloric acid, peroxides, permanganates.

2 Acetylene Chlorine, bromine, copper, fluorine, silver, mercury.3 Acetone Concentrated nitric and sulfuric acid mixtures.

4 Alkali Water, carbon tetrachloride and other chlorinated hydrocarbons, halogens, carbon dioxide.

5 Alkaline earth metals

Water, carbon tetrachloride and other chlorinated hydrocarbons, halogens, carbon dioxide.

6 Ammonia (anhydrous)

Mercury, chlorine, calcium hypochlorite, iodine, bromine, hydrofluoric acid (anhydrous).

7 Ammonium nitrateAcids, powdered metals, flammable liquids, chlorates, nitrates, sulfur, finely-divided organic materials, finely-divided combustible materials.

8 Aniline Nitric acid, hydrogen peroxide.9 Arsenical metals Any reducing agent.10 Azides Acids.

11 BromineAmmonia, acetylene, butadiene, butane, methane, propane and other petroleum gases, hydrogen, sodium carbide, benzene, finely-divided metals, turpentine.

12 Calcium oxide Water.13 Carbon (activated) Calcium hypochlorite, all oxidizing agents.

14 Carbon tetrachloride Sodium.

15 ChloratesAmmonium salts, acids, powdered metals, sulfur, finely-divided organic materials, finely-divided combustible materials.

16 Chromic acid Acetic acid, naphthalene, camphor, glycerol, alcohol, flammable liquids.

TABLE 7 continued

17 Chromium trioxide Acetic acid, naphthalene, camphor, glycerol, alcohol, flammable liquids.

18 ChlorineAmmonia, acetylene, butadiene, butane, methane, propane and other petroleum gases, hydrogen, sodium carbide, benzene, finely-divided metals, turpentine.

19 Chlorine dioxide Ammonia, methane, phosphine, hydrogen sulfide.20 Copper Acetylene, hydrogen peroxide.

21 Cumene hydroperoxide Acids.

22 Cyanides Acids.

23 Flammable liquids Ammonium nitrate, chromic acid, hydrogen peroxide, nitric acid, sodium peroxide, halogens.

24 Fluorine INCOMPATIBLE WITH ANY MATERIAL.25 Hydrocarbons Fluorine, chlorine, bromine, chromic acid, sodium peroxide.26 Hydrocyanic acid Nitric acid, alkali.

27 Hydrofluoric acid (anhydrous) Ammonia -- aqueous or anhydrous.

28 Hydrogen Iodine, flammable liquids, combustible materials.

29 Hydrogen peroxideCopper, chromium, iron, most metals and their salts, alcohols, acetone, organic materials, aniline, nitromethane, combustible materials.

30 Hydrogen sulfide Fuming nitric acid, oxidizing gases.31 Hypochlorites Acids, activated carbon.32 Iodine Acetylene, hydrogen, ammonia.33 Mercury Acetylene, fulminic acid, ammonia.

34 Nitrates Sulfuric acid.

35 Nitric acid (concentrated)

Acetic acid, aniline, chromic acid, hydrocyanic acid, hydrogen sulfide, flammable liquids, flammable gases, copper brass, heavy metals.

36 Nitrites Acids.37 Nitroparaffins Inorganic bases, amines.TABLE 7 continued38 Oxalic acid Silver, mercury.

39 Oxygen Oils, grease, hydrogen, flammable liquids, flammable solids, flammable gases.

40 Perchloric acid Oils, grease, acetic anhydride, bismuth and its alloys, alcohol, paper, wood.

41 Peroxides, organic Acids -- organic or mineral.

42 Phosphorous (white) Oxygen, alkalis, reducing agents.

43 Potassium Carbon tetrachloride, carbon dioxide, water.44 Potassium chlorate Sulfuric acid and other acids.

45 Potassium perchlorate Sulfuric acid and other acids.

46 Potassium permanganate Glycerol, ethylene glycol, benzaldehyde, sulfuric acid.

47 Selenides Reducing agents.

48 Silver Acetylene, oxalic acid, tartartic acid, ammonium compounds, fulminic acid.

49 Sodium Carbon tetrachloride, carbon dioxide, water.50 Sodium nitrite Ammonium nitrite and other ammonium salts.

51 Sodium peroxideEthyl or methyl alcohol, glacial acteic acid, acetic anhydride, benzaldehyde, carbon disulfide, glycerin, ethylene glycol, ethylacetate, methyl acetate, furfural.

52 Sulfides Acids.

53 Sulfuric acid Potassium chlorate, potassium perchlorate, light metals -- sodium, lithium, potassium permanganate, and so on.

54 Tellurides Reducing agents.

Specific hazardous materials

These sections give brief health and safety information on specific hazardous materials.

Acetylenic compounds

Acetylenic compounds are explosive mixtures with combinations with air ranging from 2.5% to 80%.

At pressures of 2 or more atmospheres, acetylene (C2 H2) subjected to an electrical discharge or high temperatures decomposes with explosive violence. Dry acetylides detonate on receiving the slightest shock.

Aluminum Chloride (AlCl3)

Aluminum chloride (AlCl3) should be considered a potentially dangerous material. It reacts violently with water or alcohols. If any moisture is present, decomposition products such as HCI vapor can build up considerable pressure in the containers.

Ammonia

WARNING

Never store ammonia near chlorine bleach.

Never mix or use ammonia with bleach.

Ammonia reacts with iodine to create nitrogen triiodide, which is explosive. Ammonia added to hypochlorites liberates dangerous chlorine gas.

Benzoyl peroxide

Benzoyl peroxide, when dry, is easily ignited and sensitive to shock. It decomposes spontaneously at temperatures above 50 ºC (122.0 ºF).

Carbon disulfide

Carbon disulfide is both very toxic and very flammable; mixed with air, its vapors can be ignited by a steam bath or pipe, a hot plate, or a glowing light bulb.

Catalysts

Catalysts such as palladium or platinum on carbon, platinum oxide, Raney nickel, and other catalysts should be filtered from catalytic hydrogenation reaction mixtures carefully. The recovered catalyst is usually saturated with exposure to air. Particularly in large-scale reactions, the filter cake should not be allowed to become dry.

Another hazard in working with such catalysts is the danger of explosion if additional catalyst is added to a flask in which hydrogen is present.

NOTE

The funnel containing the catalyst filter cake should be put into a water bath immediately after completion of the filtration.

Chlorine

Chlorine reacts violently with hydrogen or with hydrocarbons when exposed to sunlight. Chlorine gas and chlorine-producing compounds require special handling procedures. Consult the MSDS or call EH&S at 823-5323 for more information.

Diazomethane

Diazomethane (CH2N2) and closely-related compounds must be treated with extreme caution. They are very toxic; the pure gases and liquids of these compounds explode readily. Solutions are most safely kept in ether.

Dimethyl sulfoxide ([CH3]2S0)

Dimethyl sulfoxide ([CH3]2S0) decomposes violently on contact with a large variety of active halogen compounds. Dimethyl sulfoxide has a history of explosions from contact with active metal hydrides. The exact toxicity level of dimethyl sulfoxide is still unknown, but it does penetrate and dissolve substances through the skin membrane.

Dry ice

Dry ice must never be kept in a container designed to withstand pressure.

As a practical example, containers with other substances, when stored over dry ice for extended periods, can absorb carbon dioxide (CO2). If one the containers is removed from storage and allowed to come rapidly to room temperature, a dangerous hazard develops. The carbon dioxide builds internal pressure and bursts the container with explosive violence. When removing such a container from storage, loosen the stopper or wrap the container itself in towels and keep behind a shield.

NOTE

Dry ice is a cryogenic and can produce serious burns on the skin.

Always use appropriate gloves or utensils when handling dry ice. Never use your bare hands!

If a dry ice burn occurs, treat area with generous amounts of room-temperature water and follow procedures as described in Section 3.2.4: Burns and scalds.

Drying agents

Drying agents such as Ascariter must not be mixed with phosphorous pentoxide (P2O5) because the mixture may explode if it is warmed with a trace of water.

The cobalt salts used as moisture indicators in some drying agents may be extracted by some organic solvents. Restrict the use of these drying agents to gases.

Diethyl diisopropyl (and other ethers)

WARNING

Never attempt to move containers of ether that appear rusty or corroded.

Diethyl diisopropyl and other ethers are prone to exploding during heating or refluxing because of the presence of peroxides. See Section 5.3.4: Peroxides and peroxide-forming structures.

Ferrous salts or sodium bisulfate can be used to decompose the peroxides, and passage over basic active alumina will remove most of the peroxide material.

However, do not use old containers of ethers. Declare these containers as waste and contact EH&S at 823-5323 for removal.

Ethylene oxide (C2H4O)

Ethylene oxide (C2H4O) has been known to explode when heated in a closed vessel. When using ethylene oxide under pressure, conduct experiments behind suitable barricades.

Halogenated compounds

Halogenated compounds such as chloroform (CHCl3) and carbon tetrachloride (CCl4) must not be dried with sodium, potassium, or other active metal. Violent explosions are usually the result of such attempts. Also, many halogenated compounds are toxic. Use them in a well-ventilated area such as in a fumehood.

Hydrogen peroxide (H2O2)

Hydrogen peroxide (H2O2) stronger than 3% undiluted is dangerous; it causes serious burns to the skin. Thirty percent (30%) hydrogen peroxide may decompose violently if contaminated with iron, copper, chromium, and other metals or their salts.

Lithium aluminum hydride (LiAlH4)

Lithium aluminum hydride (LiAlH4) must never be used to dry methyl ethers or tetrahydrofuran. Fires resulting from this type of drying are very common. In addition, the products of the reaction of lithium aluminum hydride with carbon dioxide have been reported to be explosive.

NOTE

Do not use carbon dioxide or bicarbonate extinguishers for lithium aluminum hydride fires. Instead, smother the fire with sand or some other inert substance.

Also, do not use carbon dioxide, carbon tetrachloride, and bicarbonate extinguishers for any alkali metal fires, including lithium aluminum hydride.

Perchlorates

Perchlorates such as perchloric acid (HClO4) must be avoided wherever possible. Particularly avoid using perchlorates as drying agents if there is:

A possibility of contact with organic compounds A possibility of proximity to a dehydrating acid

strong enough to concentrate the perchloric acid to more than 70% strength, such as in a drying train that has a bubble container containing sulfuric acid.

For example, 70% perchloric acid can be boiled safely at approximately 200 ºC (392.0 ºF). But contact of the boiling undiluted acid, the hot vapor with organic matter, or even easily oxidized inorganic matter (such as compounds of trivalent antimony) will lead to serious explosions. Oxidizable substances must never be allowed to contact perchloric acid. Beaker tongs, rather then rubber gloves, should be used when handling fuming perchloric acid.

Conduct perchloric acid evaporation only in fume hoods designed specifically for that purpose. The hoods must be equipped with plumbing for washdown.

Permanganates

Permanganates are explosive when treated with sulfuric acid. When both compounds are used in an absorption train, an empty trap should be placed between them.

Peroxides -- Inorganic

Inorganic peroxides, when mixed with combustible materials such as barium, sodium, and potassium, form explosives that ignite easily.

Peroxides -- Organic

Organic peroxides are a class of compounds that have unusual stability problems that make them among the most hazardous substances used in laboratories. As a class, organic peroxides are considered to be powerful explosives. They are sensitive to heat, friction, impact, and light, as well as to strong oxidizing and reducing agents.

All organic peroxides are flammable. See Pages 83 and 84 for more information on organic peroxides. Also see Tables 6 and 7 on Pages 85 and 86.

Suggestions for safe use and storage of ether and other peroxidizable materials:

All peroxidizable materials should be stored in a cool place, away from light. Metal cans are preferable; do not store ethers in ground glass-stoppered bottles

Ethers and peroxidizable materials shall be ordered only in small quantities and should be dated upon receipt and when opened. They should be discarded within a year after receipt if unopened, or within six months of opening

Ethers shall always be handled in a hood to assure proper ventilation. This will protect individuals from inhaling the vapors and prevent accumulation of explosive concentrations of the vapor. For methods of peroxide detection and removal, consult EH&S.

NOTE

Never order excess amounts of ether!

Periodically check the condition of ether stocks!

Phosphorous (P)

Phosphorous (P) forms explosive mixtures with oxidizing agents. The reaction of phosphorous with aqueous hydroxide causes the combination to produce a gas named phosphine, which may either burst into flame spontaneously or explode in air.

The types of phosphorous are red, white, and yellow. White phosphorous is the most dangerous because it is spontaneously flammable in air. Store white phosphorous under water to prevent this spontaneous reaction.

Other solutions such as oil can be used to keep phosphorous from reacting or becoming explosive. Consult the MSDS for storage information on phosphorous. . Phosphorous trichloride (PCl3)

Phosphorous trichloride (PCl3) reacts with water to form phosphoric acid, which decomposes on heating to form phosphine, which may ignite spontaneously or explode. Open containers of phosphorous trichloride with care.

NOTE

Do not expose and heat samples of phosphorous trichloride without adequate shielding to protect yourself or the person doing the operation.

Potassium (K)

Potassium (K) is generally more reactive than sodium, igniting quickly on exposure to humid air. Potassium must be handled under the surface of a hydrocarbon solvent. Mineral oil and toluene are solvents that allow safe handling of potassium.

Destroy scraps of potassium by reaction with h-butyl alcohol.

Sodium (Na)

Sodium (Na) is stored safest in a closed container under kerosene, toluene, or other mineral oil. Destroy scraps of sodium by reaction with h-butyl alcohol. Avoid contact with water. Sodium reacts violently with water to form hydrogen and causes sufficient heat for ignition.

Sodium azide

WARNING

Do not pour sodium azide down a copper or lead drain. Lead and copper are part of a family of heavy metal azides that detonate easily and unpredictably.

Sodium azide reacts violently with benzoyl chloride plus potassium hydroxide, bromine, carbon disulfide, chromium oxychloride, copper, lead, nitric acid, dimethylsulfate and dibromomalonitrile.

NOTE

Sodium azide should not be allowed to come in contact with heavy metals or their salts. Consult EH&S when dealing with sodium azide waste.

Sulfuric acid (H2SO4)

Sulfuric acid is one of the most corrosive chemicals known to humans. The chemical is not recommended as a drying agent in dessicators. However, if sulfuric acid must be used, place glass beads in the dessicator to prevent splashing if it is moved.

NOTE

Always wear protective clothing when handling sulfuric acid.

The use of sulfuric acid in melting point baths should be avoided. Use silicone oil should be used instead.

To dilute sulfuric acid, add the acid slowly to cold water.

Trichloroethylene (Cl2CCHCl)

Trichloroethylene (Cl2CCHCl) reacts under a variety of conditions with potassium or sodium hydroxide to form dichloroacetylene, which ignites spontaneously in air and detonates readily even at cold temperatures. The compound itself is highly toxic and suitable precautions should be taken when it is used as a degreasing solvent