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Water Reactive GHS/TDG Chemical Fires sometimes you cant put the wet stuff on the red stuff!

Water reactive chemicals are chemicals that react vigorously with moisture. The most common water sensitive chemicals include sodiumpotassiumlithium metals and aluminum alkyls.

So when you look at chemical cabinets or locations site with a “W” with a line through it do you know what that means?

Water reactive substances are dangerous when wet because they undergo a chemical reaction with water. This reaction may release a gas that is either flammable or presents a toxic health hazard. In addition, the heat generated when water contacts such materials is often enough for the item to spontaneously combust or explode.

Thus, it is critical that water reactive substances be stored in dry areas and kept off the floor by the use of pallets or rack storage. Dangerous when wet materials should never be stored directly beneath active water sprinklers and should be isolated by a waterproof or water-resistant barrier (e.g., plastic sheeting or a water-tight secondary container) to protect the materials from water in the event the sprinkler system is activated elsewhere in the company facility or warehouses.

Water-reactive materials pose serious risks. The SDS will provide information about these risks as well as the precautions you should take in handling the material. Pay particular attention to the fire fighting media and procedures listed in the SDS. Make sure that your water-reactive materials are well-marked so that fire fighters and other personnel are aware of the danger in an emergency situation and be sure to have a proper Class D fire extinguisher on hand.

There are several class D fire extinguisher agents available; some will handle multiple types of metals, others will not. Sodium chloride (Super-D, Met-L-X, M28, Pyrene Pyromet* or METAL.FIRE.XTNGSHR) contains sodium chloride salt, which melts to form an oxygen-excluding crust over the metal.

In GHS we take a few more levels to ensure safety in Section 14 under Categories relating to HAZARDS now again into Divisions 1-3

Plus

Vigorous Reaction to the action

Some materials can react vigorously with water to rapidly produce gases which are deadly at low airborne concentrations. For example, sodium or potassium phosphide release phosphine gas when they contact water. Alkali metal cyanide salts, such as sodium or potassium cyanide, slowly release deadly hydrogen cyanide gas on contact with water. The cyanide salts of alkaline earth metals such as calcium or barium cyanide react at a faster rate with water to produce hydrogen cyanide gas. This can result in a life-threatening problem in confined spaces or poorly ventilated areas.

Large amounts of corrosive hydrogen chloride gas are rapidly released when water reacts with aluminum chloride, phosphorous trichloride, tin chloride and chlorosilane compounds. When water contacts thionyl chloride or sulphuryl chloride, they decompose rapidly giving off sulphur dioxide gas and hydrogen chloride gas.

Condensation is a chemical reaction in which two or more molecules join together to form a new substance. Water or some other simple substance may be given off as a by-product. Some polymers, such as nylon, can be formed by condensation reactions.

Vigorous condensation can produce more energy than the surroundings can safely carry away. This could cause a fire or explosion, or rupture closed containers.

Few common pure chemicals undergo vigorous condensation by themselves. Some members of the aldehyde chemical family, including butyraldehyde and acetaldehyde, condense vigorously, but bases or sometimes strong acids must also be present. Some commercial products sold to be mixed for specialized applications may undergo vigorous condensation if they are not stored, handled and used as directed by the chemical supplier.

What is vigorous decomposition?

Decomposition is a chemical change in which a molecule breaks down into simpler molecules. Vigorous decomposition is potentially hazardous because large amounts of energy can be released very quickly. This could result in a fire or explosion, or rupture a closed container causing the release of dangerous decomposition products. Some pure materials are so chemically unstable that they vigorously decompose at room temperature by themselves. For example, some organics are relatively safe only when refrigerated or diluted.

We get confused with self-reactivity under conditions of shock or increase in temperature or pressure?

Materials in this group are chemically very unstable. Depending on the material, they can react vigorously and, in some cases, explosively under conditions of mechanical shock such as a hammer blow or even slightly elevated temperature or pressure. Materials in this category include:

  • ammonium perchlorate
  • azo and diazo compounds
  • acetylides
  • azides
  • fulminates
  • hydrogen peroxide solutions (91% by weight)
  • many organic peroxides
  • nitro and nitroso compounds
  • nitrate esters
  • perchloric acid solutions (over 72.5% by weight)
  • picric acid
  • picrate salts
  • triazines
  • some epoxy compounds

Can vigorous reactivity with water release deadly gas?

Some materials can react vigorously with water to rapidly produce gases which are deadly at low airborne concentrations. For example, sodium or potassium phosphide release phosphine gas when they contact water. Alkali metal cyanide salts, such as sodium or potassium cyanide, slowly release deadly hydrogen cyanide gas on contact with water. The cyanide salts of alkaline earth metals such as calcium or barium cyanide react at a faster rate with water to produce hydrogen cyanide gas. This can result in a life-threatening problem in confined spaces or poorly ventilated areas.

Large amounts of corrosive hydrogen chloride gas are rapidly released when water reacts with aluminum chloride, phosphorous trichloride, tin chloride and chlorosilane compounds. When water contacts thionyl chloride or sulphuryl chloride, they decompose rapidly giving off sulphur dioxide gas and hydrogen chloride gas.

Treat all unknown materials as very hazardous until they are positively identified.

How are dangerously reactive liquids and solids hazardous to my health?

Dangerously reactive liquids and solids can be extremely hazardous. Accidental or uncontrolled chemical reactions are important causes of severe personal injury and property damage. Rapid release of very toxic or corrosive gases occurs when water contacts some dangerously reactive materials. In addition, many dangerously reactive materials are themselves toxic or very toxic. Depending on the material, route of exposure (inhalation, eye or skin contact, or swallowing) and dose, they could harm the body. The Safety Data Sheet (SDS) should describe what these hazards are for the particular product you are working with.

 

What are the fire and explosion hazards of dangerously reactive chemicals?

Highly reactive chemicals may undergo vigorous, uncontrolled reactions that can cause an explosion or a fire, or rupture sealed reaction vessels or storage containers.

Even slow reactions can be hazardous if they involve large amounts of material or if the heat and gases are confined, such as in a sealed storage drum. Drums that are swollen and distorted from over-pressurization are potentially very dangerous. They may rupture at any time without warning and release their contents.

Some dangerously reactive liquids such as methyl acrylate and acrylonitrile, are also flammable liquids. They give off enough vapour at normal workplace temperatures to form flammable mixtures with air. They can be serious fire hazards at temperatures lower than those at which they would begin to polymerize or decompose.

Fires involving dangerously reactive materials can be more hazardous than normal. The heat from the fire can lead to violent, uncontrolled chemical reactions and potentially explosive ruptures of sealed containers.

Are there other hazards associated with dangerously reactive chemicals?

Many dangerously reactive materials can also undergo dangerous reactions from direct contact with other, incompatible materials. Incompatibility hazards can be complicated. The chance of a dangerous reaction depends not just on the different combinations of chemicals involved. It also depends on the amounts of each, the surrounding conditions such as temperature, and whether the substances are enclosed in a sealed container.

The SDSs and the container labels should explain all of the hazards of the dangerously reactive liquids and solids that you work with.

So what do your Company FIRE and  Emergency SOP say in the workplace?

Water sensitive chemicals should be stored in a cool and dry location. Some materials may react with excessive humidity in the air. • Keep water sensitive chemicals segregated from all other chemicals in the laboratory. • Minimize the quantities of water sensitive chemicals stored in the laboratory. • Date all containers upon receipt. • Potassium will form peroxides and superoxides when stored under oil at room temperature. • Examine storage containers frequently. • Dispose of any container that exhibits salt build up on its exterior. • Dispose of all water sensitive chemicals whenever they are no longer required for current research. • Never return excess chemicals to the original container. Small amounts of impurities may be introduced into the container which may cause a fire or explosion.

SPILL AND ACCIDENT PROCEDURES • Before beginning work with water reactive chemicals, develop emergency procedures which address response actions to accidental exposure from fires, explosions, or spills. The procedures should address as a minimum the following: Who to contact: (Occupational Health and Safety, Ø Principal supervisor of the facility including evening phone number) Ø The location of all water reactive chemicals in the location. The method used to alert personnel in nearby areas of potential hazards Special first aid treatment required by the type of water reactive chemical(s) handled in the laboratory • Anticipate spills by having clean up equipment on hand. The appropriate clean up supplies can be determined by consulting the material safety data sheet. This should occur prior to the use of any water reactive chemicals. • Do not put water on the spill. • Spill control materials for water sensitive chemicals are designed to be inert and will not react with the reagent. • In the event of a spill, all personnel in the area should be alerted. • Do not attempt to handle a large spill of water reactive chemicals. Turn off all ignition sources and vacate the laboratory immediately and call for assistance). • Remain on the scene, but at a safe distance, to receive and direct safety personnel when they arrive.

WASTE DISPOSAL • All materials contaminated with water sensitive chemicals should be disposed of as hazardous waste. • Alert Occupational Health and Safety if you generate wastes contaminated by water sensitive chemicals. • These wastes should not remain in the facility overnight as they may pose a flammability risk.

Some EXAMPLES OF WATER REACTIVE CHEMICALS • Alkali metals, such as Na, Li, K • Alkali metal hydrides, such as LiH, CaH2, LiAlH4, NaBH4, alkali metal amides, such as NaNH2 • Metal alkyls, such as lithium and aluminum alkyls • Grignard reagents, RMgX • Halides of nonmetals, such as BCl3, BF3, PCl3, PCl5, SiCl4, S2Cl2 • Inorganic acid halides, such as POCl3, SOCl2, SO2Cl2 • Anhydrous metal halides, such as AlCl3, TiCl4, ZrCl4, SnCl4 • Phosphorus pentoxide • Calcium carbide • Organic acid halides and anhydrides of low molecular weight, such as, acetyl chloride acetic acid anhydride

Water Reactive Chemicals Which Require Tracking

Name/Description and Cas Numbers

Aluminum alkyl halides

Aluminum alkyl hydrides

Aluminum alkyls

Aluminum borohydride or Aluminum borohydride in devices

16962-07-5

Aluminum Carbide

1299-86-1

Aluminum ferrosilicon powder

Aluminum hydride

7784-21-6

Aluminum phosphide

20859-73-8

Aluminum powder, uncoated

7429-90-5

Aluminum silicon powder, uncoated

Barium

7440-39-3

Boron trifluoride dimethyl etherate

353-42-4

Calcium

7440-70-2

Calcium carbide

75-20-7

Calcium cyanamide with more than 0.1 percent of calcium carbide

156-62-7

Calcium hydride

7789-78-8

Calcium manganese silicon

Calcium phosphide

1305-99-3

Calcium silicide

12737-18-7

Cells, containing sodium

Cerium, turnings or gritty powder

7440-45-1

Cesium or Caesium

7440-46-2

Diethylzinc

Dimethylzinc

544-97-8

Ethyldichlorosilane

1789-58-8

Ferrosilicon, with 30 percent or more but less than 90 percent silicon

8049-17-0

Lithium

7439-93-2

Lithium alkyls

Lithium aluminum hydride

16853-85-3

Lithium aluminum hydride, ethereal

16853-85-3

Lithium borohydride

16949-15-8

Lithium ferrosilicon

70399-13-2

Lithium hydride

7580-67-8

Lithium hydride, fused solid

7580-67-8

Lithium nitride

26134-62-3

Lithium silicon

68848-64-6

Magnesium alkyls

Magnesium aluminum phosphide

Magnesium granules, coated, particle size not less than 149 microns

7439-95-4

Magnesium hydride

7693-27-8

Magnesium phosphide

12057-74-8

Magnesium silicide

22831-39-6

Magnesium, powder or Magnesium alloys, powder

7439-95-4

Maneb or Maneb preparations with not less than 60 percent maneb

12427-38-2

Methyl magnesium bromide, in ethyl ether

Methyldichlorosilane

75-54-7

Phosphorus pentasulfide, free from yellow or white phosphorus

7723-14-0

Potassium

7440097

Potassium borohydride

13762-51-1

Potassium phosphide

20770-41-6

Potassium sodium alloys

1113581-2

Potassium, metal alloys

7440097

Rubidium

7440-17-7

Sodium

7440-23-5

Sodium aluminum hydride

13770-96-2

Sodium borohydride

16940-66-2

Sodium hydride

7646-69-7

Sodium phosphide

24167-76-8

Stannic phosphide

25324-56-5

Strontium phosphide

12504-13-1

Trichlorosilane

10025-78-2

Zinc ashes

Zinc phosphide

1314-84-7

Zinc powder or Zinc dust

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