EH-93-2 Mixing of Incompatible Chemicals
ENVIRONMENT, SAFETY & HEALTH
BULLETIN
Assistant Secretary for U. S. Department of Energy
Environment, Safety & Health Washington, D.C. 20585
DOE/EH-0296 Issue No. 93-2 February 1993
Mixing of Incompatible Chemicals
BACKGROUND
Mixing of incompatible chemicals can result in violent explosions,
exothermic reactions, or the evolution of combustible or toxic gases.
Such chemicals pose a definite threat to the health and safety of
employees. Inadvertent mixing of such chemicals has occurred at
Department of Energy (DOE) facilities, and recent events indicate a need
for improved emphasis on how to both eliminate such incidents and protect
against their consequences should they occur.
BURNS FROM CHEMICAL SPRAY
On October 22, 1992, at the Industrial Wastewater Pretreatment Facility at
the Kansas City Plant, a subcontractor employee was performing a
treatability test on waste developer solution to determine the proper
method to recover silver. This test is routine and conducted on an
ongoing basis. Initial information indicated that the beaker contained
approximately 1000 ml of a developer and sodium hydroxide solution and 12
grams of calcium chloride. When the employee added 10 ml of a commercial
sodium hypochlorite preparation, the solution reacted, spraying the
operator's face, neck, and arms. He was wearing safety glasses and
sustained no injury to his eyes; however, other areas of unprotected skin
sustained chemical burns. Hospital treatment was necessary.
A description of this incident was also given in the Occupational Safety
Observer, December 1992, published by the Office of Safety and Quality
Assurance, Assistant Secretary for Environment, Safety and Health. A
complete safety investigation of the incident is being performed by
Allied-Signal, Inc., including analysis of a sample of the original
solution. The incident apparently resulted from the mixing of an oxidizer
with a reducing agent - an action specifically warned against on the
Material Safety Data Sheet (MSDS) for sodium hypochlorite.
OTHER INCIDENTS
Two recent incidents were directly attributed to workers inadvertently
adding nitric acid to containers of mixed chemicals: one involved ethanol
and acetone and the other involved a mixture ("piranha") of sulfuric acid
and hydrogen peroxide. Both of these incidents involved rupture of the
containers and spraying of chemical contents; no injuries resulted. Since
September of 1990, there have been at least four other incidents involving
the mixing of incompatible acids, organics, or other materials which
resulted in reactions, explosions or fire. Two employees were injured in
one of the mishaps. In addition, the incidents also involved evacuation,
emergency response, and lost time due to investigative and clean-up
requirements.
COMMONALITIES
o All or most of the incidents mentioned above involved the following:
- Routine, frequently performed procedures;
- Chemical wastes (acids, organics, and inorganics), and waste
containers; and
- Improper labeling of chemicals or waste containers.
o Causal analyses led to the following determinations:
- Procedures need to be revised or updated;
- Training needs to be provided, improved and/or made more
specific to actual hazards;
- Supervisor controls need to be upgraded;
- Additional or improved barriers/controls need to be provided.
APPLICABLE REGULATIONS AND GUIDELINES
All work environments involving hazardous chemicals are regulated by the
Occupational Safety and Health Administration (OSHA) under 29 Code of
Federal Regulations (CFR) 1910 and 29 CFR 1926, Occupational Safety and
Health Standards for General Industry, and Safety and Health Regulations
for Construction, respectively.
Particularly applicable are 29 CFR 1910.1200, Hazard Communication, and 29
CFR 1910.1450, the OSHA Laboratory Standard. DOE also requires compliance
with National Fire Protection Guidelines on storage, labeling, and
handling of chemicals. Particular standards and guides have been
referenced in a previously issued Safety Bulletin, "Safe Chemical
Storage," Issue No. 91-2, DOE/EH-0168, February 1991.
The use of eye and face protection is discussed in 29 CFR 1910.133, and
specific requirements for the design, construction, and use of devices for
eye protection are contained in the American National Standards Institute
(ANSI) Standard Z87.1 1989. The use of other worker protective equipment
is described in 29 CFR 1910 Subpart I, Personal Protective Equipment
(PPE).
DOE Order 5480.19, "Conduct of Operations Requirements for DOE
Facilities," should be reviewed with particular emphasis placed on
Guidelines Chapters covering Operations Aspects of Facility Chemistry and
Unique Processes, Required Reading, Operations Procedures, and Equipment
and Piping Labeling.
RECOMMENDATIONS
1. As required in 29 CFR 1910.1200, hazard communications training must
be provided to all employees working with hazardous chemicals prior
to their beginning work. This training should emphasize the
specific chemicals involved and should be updated when new chemical
hazards are introduced. Supervisors must verify that employees are
current in their training and aware of the proper procedures
regarding chemical processes.
2. Operating procedures should be periodically reviewed and updated as
necessary. Supervisors should observe hazardous processes
frequently to ensure compliance with and adequacy of procedures with
regard to safety. Employees should be encouraged to suggest
improvements or refinements of procedures.
3. Hazard analysis must be performed as required by 29 CFR 1910.119.
Hazard barriers and controls must be designed, implemented, and
validated prior to the commencement of chemical processes. These
analyses and controls should be periodically reviewed and updated
when necessary. Supervisors should verify that controls are in
place and are being used properly.
4. PPE must be provided commensurate with the magnitude of the hazard
(29 CFR 1910 - Subpart I). Training must be provided in the use of
this equipment; procedures must incorporate this equipment; and
supervisors must verify the correct use of the equipment.
5. Prior to mixing chemicals, workers should know what chemicals they
are using and the required precautions. Unlabeled or suspect
chemicals should not be mixed. If necessary, constituent MSDSs
should be reviewed with a focus on incompatibilities with other
chemicals. The suitability of containers used in mixing and storage
should also be determined when examining MSDSs. All involved
containers should be clearly labelled.
6. In view of the uncertain reactions from the mixing of certain
chemicals, testing procedures similar to those performed during the
incident at the Kansas City Plant should be conducted under a
properly designed chemical hood, and the worker should wear a full
face shield in addition to safety glasses.
7. Chemical mixing processes should be observed to verify that
employees are following validated, safe procedures. Refresher
training should be provided and, where practicable, employees should
have rotating responsibilities to avoid becoming complacent in their
attitudes toward the handling of hazardous materials.
8. Affected DOE personnel should review DOE Safety Notes, Bulletins,
etc., regarding chemical safety, and also periodically review the
Occurrence Reporting and Processing System (ORPS) and other sources
of lessons learned.
This Bulletin is one in a series of publications issued by EH to share
occupational safety information throughout the DOE complex. To be added
to the Distribution List or to obtain copies of the publication, call
(615)576-7548. For additional information regarding the publications,
call Barbara Bowers, Safety Performance Indicator Division, Office of
Environment, Safety and Health, U.S. Department of Energy, Washington, DC
20585, (301)903-3016.