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Session 5AControl Procedures for Acids and Bases Upon completion of this session, you will learn additional methods to protect yourself from the hazards of specific types of chemicals such as corrosives, carcinogens,
reproductive toxins, highly toxic materials, flammable and combustible liquids, laser dyes and laser dye solvents, peroxide forming chemicals and water reactives.It should take you about 10 minutes
to complete this training session. When you have read through the material, you will be asked to answer 5 questions. The information presented in this section is a summary of the hazards and controls
for these compounds. This is done for training purposes. However, if you wish to get more detailed information, please consult the CHSP.Acids and bases are extremely destructive to the eyes, skin and respiratory tract. Acids, especially in concentrated form, are most likely to cause immediate pain
upon contact with tissues. Secondary toxic effects may occur if the material is absorbed from the lungs into the blood stream. The extent of these effects depend on the concentration in air and on the
duration of exposure. Ingestion causes severe burns of the mucous membranes of the mouth, throat, esophagus, and stomach.
- The eyes are especially susceptible to acids and bases and must be immediately flushed with water if exposure occurs.
Skin contact with strong bases usually goes unnoticed since immediate pain does not occur.
Inhalation of vapors, dusts, and mists of acids and bases irritate the nose, throat, and lungs.
Concentrated solutions of inorganic acids are not in themselves flammable. Combustion can occur, however, when an acid is mixed with other chemicals or with combustible materials. Acids also react with
many metals, resulting in the liberation of hydrogen, a highly flammable gas. Some acids are strong oxidizing agents and can react destructively and violently when in contact with organic or other oxidizable
materials. Perchloric acid may form explosive perchlorate crystals which can detonate. Control Measures
- Line managers shall evaluate the use of acids and bases in the work area to determine the extent of the hazard and to evaluate the controls necessary to safeguard employee health.
MSDSs and other hazard databases should be reviewed.
An EH&S Industrial Hygienist should be contacted to provide guidance. This is expecially important for hydrofluoric and perchloric acids.
Selection and Use of Engineering Controls
- Use a fume hood or other appropriate exhaust ventilation shall be used when handling acids and bases in a manner that may produce an airborne hazard. This includes transfer operations, preparation of
mixtures, blending, sonification, spraying, and heating.
- If you use perchloric acid, make certain that you use a fume hood equipped with a water wash down system may be required. Contact an
EH&S Industrial Hygienist for further guidance.
Work Practices
- Do not pour water into acid. Slowly add the acid to the water and stir.
- Never empty carboys or drums of chemicals by means of air pressure. Use a tilting rack, a safety siphon, or a liquid pump.
- Use a mechanical aid or a pipette bulb for pipetting.
- Open bottles or carboys slowly and carefully and wear protective equipment to guard hands, face, and body from splashes, vapors, gases and fumes.
- Wipe drips from containers and bench tops. Be sure to wipe up visible residues of sodium hydroxide and potassium hydroxide from all surfaces. Skin contact with dry residue will result in burns.
Storage Detailed storage procedures and incompatibilities
can be found in Storage Guidelines
of the CHSP. General guidelines are presented below:
- Store acids and bases separately from each other and from other incompatible chemicals. For example, store oxidizing acids (such as nitric, perchloric and sulfuric acids) separately from flammable liquids.
- Use storage lockers specifically designed for acids and bases connected to exhaust ventilation if possible.
Note: It is Laboratory policy that storage cabinets located in new facilities and laboratory renovations will be connected to the facility's exhaust ventilation system.
Please store all corrosives in sealed, air-impermeable containers. Containers with tight-fitting caps are recommended. Containers with loose fitting lids or glass stoppers should not be used.
Other Considerations
- For mixed spills (radiological and chemical) contact the assigned
Radiological Control Technician
before initiating any clean up activities.
Laboratories and shop areas where acids and bases are handled should have an adequate number of appropriate spill kits to meet anticipated needs. These are commercially available through VWR Scientific (the Laboratory has a contract with this vendor)
Hydrofluoric acid can not be cleaned up with normal acid spill kits. These contain sodium bicarbonate which reacts violently with hydrofluoric acid. Special spill kits containing a magnesium sulfate
pretreatment agent are required. These are also available through VWR Scientific.
An emergency eyewash and safety shower
shall be located in all areas where acids or bases are used. In the event of skin or eye contact, flush the affected area for at least 15 minutes and report to Health Services for evaluation and treatment.
Any suspected skin contact with hydrofluoric acid or gas should be treated with flushing as described above. Flushing may remove surface hydrofluoric acid but it does not affect the fluoride ion that may
have penetrated to the deep tissue layers. The most appropriate treatment is to use 2.5 % calcium gluconate gel. Liberally apply the gel, which is available through Health Services
at no charge, to the affected areas (not the eyes) and report to Health Services immediately. All work areas where hydrofluoric acid is used shall have an ample supply of calcium gluconate gel.
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