Control Procedures for Water-Reactive Chemicals
Water-reactive chemicals react violently with water, releasing heat and, in some cases, explosive by-products. Of chief concern are the alkali metals. Alkali metals react vigorously with water to form the hydroxide and gaseous hydrogen. The alkali metal-water reaction is exothermic. The heat generated can ignite the hydrogen gas. The rate of reaction and the hazard severity increase as atomic weight increases. Lithium reacts slowest and poses the least hazard. Rubidium and cesium react explosively. A DOE document entitled “DOE-HDBK-1081-94, Primer on Spontaneous Heating and Pyrophoricity” provides additional information.
- Work Leads are responsible for identifying water reactives used in the work area. Review sources such as MSDSs for specific compounds.
- An assessment of the hazards and controls in place is necessary to safeguard employees against these agents. Contact an EH&S Industrial Hygienist to provide assistance.
- Most operations involving these materials require an AHDs. This is determined by the using Division in accordance with the provisions in PUB-3000, Chapter 6, “Safe Work Authorizations.”
Training and Information
- All employees who handle or may be exposed to water-reactive chemicals are required to attend Chemical Hygiene and Safety training EHS 348 (or 345 for Facilities personnel or 352 for summer students).
- These individuals should be trained in the specific hazards and controls of the water-reactives. This is a line management responsibility.
- Consult the section entitled: Labels, for labeling requirements for primary and secondary containers.
- The area entrance should be posted with a Caution Placard depicting the hazards and emergency contact information.
Substitution and Chemical Inventory Management
- Identify and use safer chemical alternatives (e.g., non-water- reactive chemicals) if possible.
- If a safer chemical can’t be used then limit what you buy or borrow what you need from a colleague in your group or contact the Chemical Management System coordinator to assist you in finding a source of the chemical at LBNL.
- Conduct periodic clean outs to prevent accumulating unneeded chemicals.
- Procure and use the minimum amount of material required for the operation, or
- Keep working quantities of chemicals to a minimum. Don’t stockpile chemicals.
- Enter these materials into the Chemical Management System (CMS).
Alkali metals should be handled in a glovebox made of materials that are compatible with the metal with an inert gaseous atmosphere such as dry argon.
- Do not eat, drink, smoke, chew gum, apply cosmetics, or store food, beverages, and tobacco products in work areas where water-reactive materials are being used.
- General traffic should be prohibited in areas where alkali metal operations are performed.
- Avoid all skin and eye contact with the material. Where possible use tongs or appropriate tools to handle solids.
- All tools used to handle alkali metals must be dry, rust-free, clean, and composed of a material compatible with the metal. Tools can be dried by baking in an oven, desiccating in a vacuum, or rubbing with anhydrous dry soda ash.
- Oxidized materials (with a white surface coating) make the material more hazardous to handle because the oxide can flake off. NOTE: Materials with a yellow or orange coating may indicate the presence of peroxides, which may detonate if cut or abraded. Do not handle these materials. Contact an EH&S Industrial Hygienist for further guidance.
- Assume that containers with alkali metals contain flammable hydrogen gas in the head space, even if stored under mineral oil or an inert gas. Thus, no source of ignition should be present where these containers are opened. Use nonsparking tools to open containers.
Personal Protective Equipment (PPE)
Skin and eye contact shall be prevented. The following PPE should be worn when handling these materials. Additional information may be found in the “Personal Protective Equipment” Section:
- At a minimum, safety glasses with side shields, laboratory coats (coveralls are acceptable in shop settings), and closed-toe shoes will be worn when handling these materials. For alkali metals, the shoes should be leather. This is to be considered as minimum protection and must be upgraded if necessary.
- Additional PPE such as chemical goggles, face shields, chemical aprons, fire retardant aprons, disposable coveralls, chemically resistant gloves, and respiratory protection must be worn if there is a greater chance of chemical exposure. An EH&S Industrial Hygienist may be contacted for assistance in selecting appropriate gloves and respiratory protection. The use of respiratory protection requires an industrial hygiene hazard evaluation and a medical clearance followed by a fit test and training by the Industrial Hygiene Group.
- Consult “Eye and Face Protection” in the Personal Protective Equipment Section for guidance on the selection, uses, and limitations of safety glasses, chemical goggles, and face shields.
- Since many chemicals are skin-absorbers (i.e. agents that readily pass through the skin) it is important to select gloves that are chemically resistant to the material. Consult the PPE section. This contains a list of skin-absorbing agents and provides detailed guidance for selecting chemically resistant gloves.
- Gloves must be selected on the basis of their chemical resistance to the material(s) being handled, their suitability for the procedures being conducted, and their resistance to wear as well as temperature extremes. Improper selection may result in glove degradation, permeation of the chemical through the glove and ultimately personal exposure to the chemical. This is a potentially serious situation. Consult “Gloves” in the Personal Protective Equipment Section for guidance on the selection, uses, limitations, and disposal of chemically resistant gloves. An EH&S Industrial Hygienist may also be contacted for assistance in selecting appropriate gloves.
Consult the section entitled Storage Guidelines for hazardous material storage requirements, recommendations and information on chemical incompatibility. It is recommended that alkali metals be stored in manufacturer-provided containers, if practical. Requirements for storing water reactive chemicals are provided below.
- Separate alkali metals from incompatible chemicals. In addition to being water-reactive, alkali metals can react with oxygen, acids, halogenated hydrocarbons, and carbon dioxide.
- Store alkali metals under mineral oil or in an inert atmosphere. NOTE: Lithium may react with nitrogen to form nitrides.
- Consult the “Emergency Procedures and Equipment” section for emergency actions regarding chemical spills and personal exposure to chemicals.
- In addition to these requirements, the following applies to spills of water-reactive compounds:
- Never use combustible or reactive materials (such as paper towels) to clean up spills. Keep an adequate number of appropriate spill kits to meet anticipated needs.
- Anhydrous dry soda ash may be used for all metals except lithium. Lith-X fire extinguishers must be used for lithium. Met-L-X metal fire extinguishers may be used for sodium, potassium, and sodium-potassium (NaK) alloys. Employees involved in metal work must be trained in the use of these extinguishing materials.
- Only trained personnel should attempt to control small, contained fires or spills. If fumes escape into the breathing zone of these personnel, do not attempt to put out the fire. Large or unconfined fires or spills, or fires where the ventilation system does not contain all of the fumes, should be handled only by Fire Operations (7-911).
Skin or Eye Contact
- If any alkali metal fragment or drop enters the eye, it will immediately generate considerable heat, which is likely to result in severe eye injury. In such cases, the eyes should be flushed with water from an eyewash/safety shower. Continue to flush the eye with water while someone dials 7-911 for emergency help.
- When alkali metal comes in contact with the skin, remove all contaminated clothing. If contact with the metal occurs at only one or two spots on the skin, it is best to wash off those areas with mineral oil. A container with at least one quart of mineral oil should be available in alkali metal work areas labeled for this purpose. If contact with the metal is widely distributed over the body, a decision on the best course of first aid must be made immediately. If the material is already burning, the individual should be drenched continually under a safety shower until emergency help arrives. If the material is not burning, the metal should be removed by wiping the skin with mineral oil. In all cases, dial 7- 911 for assistance.