Table of Contents
Table of Contents
1.
2.
3.
4.
Emergency Information...................................................................................................2
Dow Corning Chlorosilane Handling and Delivery Standard ......................................3
Introduction ......................................................................................................................4
Health and Safety............................................................................................................. 6
Health considerations ............................................................................................................ 6
Acute toxicity ............................................................................................................... 6
Chronic toxicity ............................................................................................................ 6
Educating employees for job safety ..................................................................................... 7
Protective clothing and equipment....................................................................................... 7
Eye and face protection ............................................................................................... 7
Respiratory protection ................................................................................................. 8
Body and foot protection.............................................................................................. 9
Cleaning and repairing equipment............................................................................... 9
Fires ................................................................................................................................... 10
Fire hazards and protection ....................................................................................... 10
Burning characteristics .............................................................................................. 10
Fire prevention........................................................................................................... 10
Fire extinguishing ...................................................................................................... 10
Firefighting techniques ...............................................................................................11
Fixed fire protection ................................................................................................... 12
Instability and reactive hazards ................................................................................. 13
Waste disposal and spill containment ............................................................................... 17
Disposal methods ...................................................................................................... 17
Special handling procedures for Si-H-containing chlorosilanes ............................... 18
Containing spills ........................................................................................................ 18
5. Engineering .................................................................................................................... 14
Building design..................................................................................................................... 14
Equipment design ................................................................................................................ 14
Ventilation ............................................................................................................................. 16
Electrical equipment ............................................................................................................ 16
Static electricity .................................................................................................................... 17
Preparing new equipment.................................................................................................... 17
6. Containers ...................................................................................................................... 20
General handling .................................................................................................................. 20
Shipping, marking, labeling and placarding ............................................................... 20
Container handling .................................................................................................... 20
Container selection .............................................................................................................. 21
Tank car .................................................................................................................... 22
Domestic tank truck ................................................................................................... 22
Portable tank (large) .................................................................................................. 23
Portable tank (small).................................................................................................. 23
For more information ........................................................................................................... 24
2
Emergency Information
1. Emergency Information
Begin first aid immediately in all cases of contact
with chlorosilanes. See the Health and Safety
section of this guide.
For emergencies in specific geographic areas, call
one of the following numbers:
In the U.S.
For assistance with any U.S. area emergency
involving Dow Corning chemicals in transport, call
Dow Corning Emergency Response:
In Asia
For emergencies in Japan and other Asian
countries, call Dow Corning’s plant in Chiba, Japan
at 81-436-213101
or dial either of the numbers listed below under
other areas.
Other areas
For emergencies outside the areas listed above,
call CHEMTREC at 202-483-7616
or Dow Corning at 989-496-5900.
989-496-5900
or CHEMTREC: 800-424-9300
In the District of Columbia, call 483-7616.
In Canada
For emergencies in Canada, call the Canadian
Transport Emergency Centre (CANUTEC):
613-996-6666.
In Mexico
For emergencies in Mexico, call SETIZ at
91-800-00-214 in the Mexican Republic.
For calls originating in Mexico City and the
metropolitan area, call 575-0838.
For calls originating in other areas, call
52-5-575-0838.
In Brazil
For emergencies in Brazil, call
Abiquim/Pro-quimica: 55-11-800-8270.
In Europe
For emergencies in Europe, call Dow Corning in
Barry, Wales at 44-1446-732350.
3
Standard
2. Dow Corning Chlorosilane
Handling and Delivery Standard
Dow Corning subscribes to the Principles of Responsible Care®. As part of our implementation of
the Product Stewardship and Distribution Codes,
Dow Corning has established the following standard
in regards to our sale and delivery of chlorsilanes.
Dow Corning will ship chlorosilanes in containers that meet or exceed industry standards using
carriers who have been adequately trained in the
hazards of these materials. We will maintain an
emergency response system which will allow
Dow Corning to respond upon request to an incident.
Dow Corning will offer existing and potential customers assistance in developing safe handling
procedures and system design for the site consistent with ASTM Standard Chlorosilane Emergency
Response Guidelines. Other references include
Dow Corning's The Introductory Guide to the Safe
Handling of Chlorosilanes and associated container
guides as appropriate.
By assisting chlorosilanes customers it is not the
intent of this standard for Dow Corning to assume
the responsibility for customer's safe handling. That
responsibility remains with the customer.
As a condition of sale, Dow Corning will assess the
capabilities and procedures of potential customers
to determine their abillity to safely unload and store
chlorosilanes. We will not ship chlorosilanes to facilities who do not meet our minimum requirements
for safe handling and storage.
4
Policy
Introduction
Introduction
3. Introduction
This guide is not meant to stand alone as an
exhaustive reference or a field manual. It was
developed to:
•
Serve as an introduction to the safe handling
of chlorosilanes.
•
Be used as a tool in developing individualized
training or review programs, on-site field
references or placards, and other educational
and safety tools.
•
Provide background on safety and
environmental issues.
•
Serve as a starting point for customers to
prepare their own literature
The information in this guide is organized and
presented to help engineers, chemists, managers,
trainers and safety representatives determine the
required scope of adequate training programs for
their own needs. Beginning with the information in
Dow Corning
Prod. No.
Chemical Name
Z-1212
this guide and referencing the detailed supporting
documents cited for specific handling activities,
customers can tailor specific procedures and
materials for their own sites.
Training programs in the safe handling of chlorosilanes—both for new and experienced users—are vital in protecting people and the environment. Dow Corning welcomes comments and
suggestions from customers regarding this guide
and related documents.
For additional product information, or if you have
questions or suggestions, call Dow Corning Customer Service at (989) 496-6000.
This guide presents necessary precautionary
information for those who use, handle or are otherwise exposed to chlorosilanes. Although a large
number of chlorosilanes can be manufactured,
relatively few are supplied by Dow Corning in
commercial quantity. Some of the most common
are listed in the following table.
Other Name
Formula
CAS No.
Ethyltrichlorosilane
C2H5SiCl3
000115-21-9
Z-1213
Proyltrichlorosilane
C3H7SiCl3
000141-57-1
Z-1216
Phenyltrichlorosilane
(C6H5)SiCl3
000098-13-5
Z-1223
Diphenyldichlorosilane
(C6H5)2SiCl2
000080-10-4
Z-1218
Methyldichlorosilane
Methyl hydrogen dichlorosilane
CH3HSiCl2
000075-54-7
Z-1219
Dimethyldichlorosilane
---
(CH3)2SiCl2
000075-78-5
Trichlorosilane
Silicon chloroform
HSiCl3
010025-78-5
Z-1211
Methyltrichlorosilane
Monomethyl trichlorosilane
CH3SiCl3
000075-79-6
Z-1229
Silicon tetrachloride
Silicon chloride tetrachlorosilane
SiCl4
010026-04-7
Z-1224
Trimethylchlorosilane
Trimethyl monochlorosilane
(CH3)3SiCl
000075-77-4
5
Introduction
Introduction
Chlorosilanes are clear liquids that readily react with
water to form corrosive hydrogen chloride gas and
hydrochloric acid. Many evolve hydrogen gas during
exposure to water. All—except silicon tetrachloride—
are either flammable or combustible.
Because chlorosilanes and their vapors are
corrosive to the skin, eyes, nose and throat, it is
important to wear goggles, face shields, chemical
protective clothing and chemical resistant gloves
when handling them. (See Protective clothing and
equipment for more information.)
Consult this guide for information on the hazards of
chlorosilanes and suggestions for their safe handling
and use. In addition, be certain to obtain a Material
Safety Data Sheet (MSDS) from Dow Corning for
each product you use. The MSDS may provide more
specific detail related to your individual application.
For detailed properties of the materials described in
this guide, refer to the applicable Material Safety Data
Sheet or contact the appropriate Dow Corning Steward
through Customer Service at (989) 496-6000.
4. Health and Safety
It is important to obtain a Material Safety Data Sheet for each chlorosilane product you use.
6
Health and Safety
Health considerations
Acute toxicity
Inhalation
Chlorosilane vapors react readily with moist air to
produce significant amounts of hydrochloric acid
(HCl) vapor, as well as some silanol, hydrogen gas
(in the case of SiH) and small amounts of polymer.
Although federal standards for exposure to chlorosilane vapor have not been set, Dow Corning recommends that workers be protected by maintaining
chlorosilane vapors below the level that produces
an irritating concentration of HCl. The current
exposure limit value for HCl is 5.0 ppm as a ceiling
limit.1 Progressively higher chlorinated silanes (e.g.,
dichloro- and trichlorosilanes) may generate greater
amounts of HCl on a molar basis than monochlorosilanes. Like HCl, chlorosilanes are easy to detect
by odor or irritation at extremely low concentrations.
Chlorosilane inhalation primarily affects the upper
respiratory tract, causing inflammation, edema and
corrosive burns of the oral, nasal and pharyngeal
mucosa and the upper airways. Potentially fatal
complications could include laryngospasm and laryngeal edema. Reversible bronchitis also has been
observed after inhalation of chlorosilane vapors.
Aspiration of liquid chlorosilane could cause chemical pneuomonitis.
As a result of industrial exposure, it is possible that
chlorosilane vapors could penetrate into the lower
airways and cause acute or delayed noncardiogenic
pulmonary edema or adult respiratory distress syndrome (ARDS). Although this response has never
been observed, it should always be clinically considered in the evaluation of patients with inhalation
exposures. The penetration of chlorosilane into the
lower airways is a theoretical possibility with lower
vapor concentrations or involuntary exposures in
confined areas.
Emergency response
•
Remove any person overcome by chlorosilane
vapor or hydrochloric acid fumes from the
contaminated atmosphere at once.
•
Symptomatic or severe inhalation exposures
should be promptly medically evaluated.
Skin contact
May cause first to third degree burns, depending
1
Health and Safety
on concentration and length of exposure. Severe
chlorosilane burns resulting from contact with liquid may require skin grafting.
Emergency response
In case of skin contact or clothing contamination:
•
Begin an emergency shower immediately.
Remove all clothes and shoes while under
the shower. Continue washing for at least 15
minutes. Washing in an enclosed area may
result in the generation of HCl fumes and
subsequent exposure.
•
Using gloves, bag and clean removed clothing.
Do not wash with other clothing. It may be
necessary to dispose of clothing.
Eye contact
May cause corrosive damage or significant irritation
that may result in total loss of sight. Corrosive cornea
burns are a possibility.
Emergency response
•
Contact lenses MUST be removed.
•
Irrigate eyes immediately with water for 15
minutes.
•
All individuals with eye exposure should be
medically evaluated.
Ingestion
May cause severe corrosive burns of the mouth,
esophagus and stomach, potentially resulting in
perforated viscus with subsequent chemical pleuritis, mediastinitis and peronitis.
Emergency response
•
Do not induce vomiting.
•
All individuals ingesting liquid chlorosilane
must be medically evaluated and treated
immediately on an emergency basis.
Chronic toxicity
Repeated skin contact with dilute solutions of
chlorosilane or HCl mists may cause irritant dermatitis. After cessation of exposure and symptomatic
therapy, these manifestations disappear with no
permanent demonstrable residual pathology. Although chronic irritant bronchitis or erosion of tooth
enamel have been observed with chronic excessive
hydrochloric acid mist or vapor exposures, these
responses have not been observed in industrial
29 CFR 1910.1000 and American Conference of Industrial Governmental Hygienists, 1997.
7
Health and Safety
Health and Safety
populations using chlorosilanes.
Educating employees for job safety
Safe handling of chlorosilanes depends to a great
extent on effective employee education, on proper
training in safe practices and use of equipment, and
on knowledgeable supervision.
•
Seek supplementary information and
assistance (see supplementary reading list).
•
Consult with industrial hygiene and safety
specialists before finalizing a safety review of
operations involving chlorosilanes.
As part of employee training for those engaged in
handling or processing chlorosilanes, supervisors
should:
•
Review each procedure in a step-by-step
manner with workers directly involved in
the use and handling of these materials. All
danger points associated with the work should
be identified and precautionary measures
determined.
•
Assess the need for personal protective
equipment; discuss proper use and limitations.
•
Establish procedures for all foreseeable
emergencies, including the location and
operation of safety showers, fire extinguishers,
alarms and other safety equipment.
•
Emphasize the importance of water washing in
the safety shower/eyewash for a minimum of
15 minutes after contact with chlorosilanes.
•
Stress the removal of contaminated shoes and
clothes. Another person may be needed to
help remove clothing or hold the eyes open in
the eyewash.
•
Teach employees the chemistry and chemical
reactions of the process as well as any
potential cross contamination in the existing
equipment or common shared equipment.
This safety review should be made at least once a
year for all chemical processing operations, and it
should always be done before any change in process. It is the supervisor’s responsibility to periodi-
8
AV11392
Before beginning employee training for those
engaged in handling or processing chlorosilanes,
supervisors should:
•
Be thoroughly familiar with the contents of the
Material Safety Data Sheets.
Employee education is vital to the safe handling of chlorosilanes.
cally check that the employees are following instructions and precautions as directed. When training
new workers, it is also important to review complete
operating procedures and safety information.
Protective clothing and equipment
In emergency situations and in certain operations
involving chlorosilanes, full protective equipment
is essential. Training in the correct use of personal
protective equipment also is essential. However,
personal protective equipment is not an appropriate substitute for safe working conditions, adequate
ventilation and intelligent conduct on the part of
employees working with chlorosilanes.
When taking samples, opening equipment or performing similar operations where chlorosilane vapor
or liquid may be present, it is important to wear appropriate personal protective equipment and clothing.
Eye and face protection
Because eye and skin contact with chlorosilanes
can result in permanent effects, the need for protective wear cannot be overstated.
•
Chemical splash goggles should be worn
whenever there is danger of chlorosilane
coming in contact with the eyes. Goggles
should be properly fitted.
•
Safety glasses with unperforated side shields
should be used where continuous eye
protection is desirable, as in laboratories,
manufacturing areas, shipping and receiving,
and storage areas; however, these glasses
offer limited protection. Safety glasses are
Health and Safety
Health and Safety
AV11395
Respiratory protection
It is critical that employees be trained in the
proper use of protective clothing and equipment.
Severe exposure to hydrochloric acid vapor may
occur during chlorosilane equipment cleaning and
repairs, or in cases of failure of piping or equipment. Employees who might be subject to such exposure should be provided with proper respiratory
protective equipment and trained in its use and
care.2 The following types of respiratory apparatus
may be used:
•
Self-contained breathing apparatus. Both the
self-contained breathing apparatus, permitting
the wearer to carry a supply of breathing air
in a cylinder, and the self-generating type,
which produces oxygen chemically, allow
considerable mobility. However, the length
of time for which either apparatus provides
protection varies according to the amount of air,
oxygen or regenerating material carried. In all
cases, the apparatus should be equipped with
a face piece that maintains positive pressure
at all times. This feature prevents any flow of
contaminated atmosphere into the face piece.
•
Air line full-face masks. Positive pressure
(continuous flow or pressure demand) air
line masks, supplied with clean, compressed
certified breathing air, are suitable for
nonemergency use, such as routine
maintenance tasks. When masks are supplied
with air piped to the area from a compressor,
it is extremely important that the air supply be
taken from a safe source and also that it is not
contaminated by oil or carbon monoxide from
the compressor. Dow Corning recommends the
use of a separate breathing air compressor of
the type not requiring internal lubrication. It is
critical to positively identify breathing air lines.
Pressure reducing and relief valves, as well as
suitable traps and filters, should be installed
at all mask stations. An alternative method is
high-pressure breathing air from standard size
cylinders, with a pressure-demand type valve
and face piece. A small cylinder of compressed
air may be worn as an additional precaution
with the pressure-demand mask for use as an
emergency escape from the area. Consult a
reliable safety equipment dealer for details on
the proper use of NIOSH-approved equipment.
•
Cartridge/disposable respirators. NIOSHcertified cartridge respirators have limitations
that make them appropriate only in restricted
inadequate and should not be used when
complete eye protection is needed, such as
when handling bulk quantities, where there is a
danger of splashing, or if the material may be
under pressure.
•
Plastic face shields should be full length,
measuring a minimum of 20 cm (8 in) with
forehead and ear protection, and they should
be worn in addition to chemical splash goggles
where face protection is desired. Chemical
splash goggles should always be worn as
added protection where there is danger of
material striking the eyes from under or around
the sides of the face shield. Face shields and
goggles are not required if a full-face respirator
is used.
•
Contact lenses are not recommended for
wear where there is risk of exposure to
chlorosilanes. Contact lenses may trap
material between the lens and eye, inhibiting
the satisfactory removal of the material by an
eye wash, and possibly causing serious eye
damage.
Respiratory protective equipment should be certified by the National Institute of Occupational Safety and Health (NIOSH). It should
be carefully maintained, inspected, cleaned and sanitized at regular intervals, and always before use by another person.
2
9
Health and Safety
Health and Safety
applications. These respirators may provide
inhalation protection when working with
chlorosilanes if the proper cartridge for
absorbing hydrochloric acid and organic vapor
(OVAG type) is used. They are not suitable
for conditions where there is a lack of oxygen.
They should be used only for short exposure
periods and are considered adequate
only for concentrations up to 10 times the
exposure limit for half masks, and 100
times the exposure limit for full-face masks.3
Cartridge respirators should never be used
for emergency ingress or in areas of unknown
vapor concentrations or oxygen content.
The wearer must be warned to leave the
contaminated area immediately upon detecting
any odors through the respirator. The odor
may indicate that the mask is not functioning
properly, that the vapor concentration is too
high, or that the mask is not properly fitted.
Body and foot protection
Protective clothing offers protection only for a
limited time, but it should allow the exposed person
sufficient time to leave the contaminated area and
reach a safety shower.
•
PVC or neoprene protective work clothes give
limited protection. Protective clothing, suit and
glove materials that provide skin protection
against HCl do not always provide the same
level of protection against chlorosilanes.
Recommended suit materials are CPF II,
CPF IV and Responder (Kappler); Chemrel
(Chemron); and Saranex 23P coated Tyvek
and Tychem 7500 (DuPont). If the chemical
in use is flammable, consider using flameretardant protective clothing.
•
•
•
Cleaning and repairing equipment
Cleaning, repair and entry of chlorosilane equipment
should be under the direction of fully trained personnel who are familiar with all hazards. All precautions
related to protective equipment and health and fire
hazards should be reviewed and understood by all
personnel working on the equipment.
The hazardous nature of tank entry inspection,
cleaning and repair requires that the foreman and
crew be carefully selected and trained. Preparing
a checklist work procedure for the entire process
(which recognizes all possible hazards as they
might occur) is a particularly effective way to maintain worker safety.
If for any reason you cannot follow all the steps
outlined below, discontinue the process immediately
and contact Dow Corning for further instructions.
•
The tank or equipment to be cleaned must first
be emptied of all liquids.
•
Close pipelines into or out of the tank or other
apparatus, and disconnect them by installing a
blank flange on the open end to protect against
human error and unsuspected leaks. (Use
OSHA lockout/tagout procedures.) Do not rely
on valves and previously installed blank flanges
in the pipeline unless they have been checked.
•
Tanks and equipment used for the first time for
chlorosilane service must be cleaned of any
contaminants, including rust.
Hand and arm protection can also be provided
on a limited basis through the use of longsleeved PVC, neoprene or butyl rubber
gloves or gauntlets that cover the forearms
and are properly sealed under coat sleeves.
Recommended glove materials are Safety First
(4H), North (Silvershield) or any Viton® type
glove.
•
Purge the tank or equipment through the vent
system with an inert gas. Check to be certain
that the oxygen content is less than 4% in the
tank or equipment.
•
After purging, open all top openings and fill the
vessel rapidly with water; then, while vented,
drain the water to a safe location as rapidly as
possible.
Rubber boots or rubber-coated, high-top
safety-toed shoes with shoe tops tucked under
pants or coveralls provide limited protection to
the feet and lower legs.
•
Measure the pH of the remaining liquid. If it is
acidic, neutralize with sodium bicarbonate.
•
Continue to flush with water until all solids are
removed. Inserting a steam hose to boil the
water helps loosen solids.
“Hard” hats or caps as described in Safety
3
10
Requirements for Industrial Head Protection,
American National Standards Institute, Z89.1,
should be worn whenever there is a possible
head hazard. Their use also is recommended
in processing, loading or unloading operations.
American National Standard for Respiratory Protection, Z88.2. 1992 Edition.
Health and Safety
•
Continue to observe the pH; if it becomes
acidic, immediately discontinue heating, but
continue to flush with water.
•
When the tank is completely free of visible
solids, steam it to vaporize any minute residue.
•
Drain the tank and allow it to dry.
Fires
Fire hazards and protection
With the exception of silicon tetrachloride, the chlorosilanes covered in this guide are classified as flammable or combustible liquids, as defined by National
Fire Protection Association (NFPA) Standard No. 30,
“Flammable and Combustible Liquids Code.” Silicon
tetrachloride is classed as noncombustible. It poses
no known fire or explosion hazards.
•
Chlorosilane vapors are heavier than air, and,
except for trimethylchlorosilane, the liquids
themselves are heavier than water. All react
vigorously with water to produce hydrogen
chloride. SiH-containing chlorosilanes
such as trichlorosilane (HSiCl3) and
methyldichlorosilane (CH3HSiCl2) react with
water and base or water and acid to release
hydrogen gas. Trimethylchlorosilane and
dimethyldichlorosilane also produce a siloxane
that is a flammable liquid.
•
Chlorosilanes are nonconductors and therefore
can accumulate static electrical charges when
processed, handled or dispensed.
Burning characteristics
Most chlorosilanes burn freely, giving off a grayishblack smoke. In addition to normal products of combustion, the smoke contains hydrogen chloride and
fumed silica (silicon dioxide). However, trichlorosilane smoke is a dense, light gray or white color. As
the carbon content in the burning material increases,
the smoke becomes darker gray in color.
Trichlorosilane burns much cooler than other chlorosilanes and hydrocarbons. It ignites with a rapid
flash-over at the liquid surface and generates very
little noticeable flame.
Fire prevention
As with all flammable liquids, fire prevention is
extremely important when using or storing chlorosi-
Health and Safety
lanes. A preventive approach includes measures
to minimize ignition potential, as well as the design
of equipment and facilities to prevent release of
chlorosilanes.
No special fire prevention measures other than
those typically recommended for flammable liquids
are necessary. These include, but are not limited to,
the following:
•
Provision of mechanical exhaust ventilation to
remove flammable vapors.
•
Provision of adequate drainage and collection
facilities to isolate any spilled liquids.
•
Provision of classified electrical equipment
according to Article 500 of the National Electric
Code (NEC).
•
Purging and inerting of equipment and
containers with an inert gas.
•
Control of static electricity.
•
Control of cutting, welding and other “hot work”.
•
Control of smoking and other potential ignition
sources.
Specific details on fire prevention measures can be
found in other sections of this guide, as well as in
various NFPA standards.
Fire extinguishing
All chlorosilanes react with moisture in the air to
form hydrogen chloride.
The primary objective of a response to a chlorosilane spill or fire should be to limit the chlorosilane/
hydrogen chloride vapor release, which will be done
by minimizing the amount of water contacting the
chlorosilane liquid. Fighting the fire should be considered secondary to this primary objective.
When wind patterns are expected to remain stable
and calm (i.e., little or no wind as determined by
observation of a vertical smoke plume from the fire),
it may be preferable to let a chlorosilane fire burn
rather than attempt to extinguish it. Rising air currents will carry the hydrogen chloride vapor cloud
to higher elevations where the cloud will disperse,
reducing the risk of overexposure to personnel at
ground level. Since this method depends on stable
and calm conditions, it must be monitored closely.
If conditions change, consider another means of
mitigating the emergency, as suggested below.
11
Health and Safety
Health and Safety
Caution: Prevent extinguishing agents from
entering a container that contains chlorosilane. The
resulting release of hydrogen chloride vapors may
overpressurize the container, resulting in sudden
rupture.
Experience with fighting chlorosilanes on a large
scale has been extremely limited. Much experience
has been either in a controlled test environment or
on a relatively small scale. Actual fire conditions
could present unique and challenging firefighting
situations and, in some cases, fire extinguishment
could be extremely difficult. For this reason, the
specific situation must be thoroughly analyzed
before attempting to fight a chlorosilane fire, and
extreme caution must be exercised during firefighting operations. In some cases, the best alternative
may be to protect personnel and important facilities
and to allow the fire to burn itself out.
Firefighting techniques
Chlorosilane fires are not easily extinguished by
conventional firefighting techniques.
Water:
•
Do not use water as an extinguishing agent.
•
Water increases the production of hydrogen
chloride, which can cause injury to personnel
downwind, and it will not readily extinguish the
fire.
•
Water should never be allowed to enter a
vessel containing chlorosilanes. The reaction
could easily overpressurize the vessel.
•
Water can be used to keep the vessels cool.
•
Water can be used to protect personnel and
exposures from radiant heat as long as it does
not contact the fire.
•
Water can be used to disperse, dilute and
scrub HCl given off by the fire.
Dry chemical based fire extinguishers:
•
Applying dry chemical to a trichlorosilane or
methyldichlorosilane fire results in a rapid
release of hydrogen, which substantially
accelerates the fire.
Aqueous foam:
•
Aqueous foam is the best extinguishing agent
for a chlorosilane fire.
•
Aqueous foam can also be used to reduce the
amount of vapor release from a spill or fire.
The best foam for this use is an AFFF alcoholcompatible foam applied at a medium expansion
ratio (30:1 to 70:1). A low expansion ratio (less than
30:1), whether alcohol-compatible or not, may be
effective on some chlorosilane fires. Tests have
shown that nonalcohol-compatible foam is not effective on trichlorosilane or methyldichlorosilane fires,
and that it does not provide good vapor suppression
for any chlorosilane. Medium-expansion foam gives
the best results on chlorosilanes. It minimizes the
amount of water present in the system, while providing a relatively thick foam blanket to react with
the chlorosilane vapors, thus reducing the amount
of hydrogen chloride vapor that reaches the surrounding environment.
When using foam:
•
Match the foam concentrate with the foam
eductor line (proportioning system) and the
foam nozzle.
•
Maintain correct pressure drop across the
eductor and pressure at the foam nozzle. This
helps ensure a foam of the right expansion with
slow water drainage and the correct dilution of
foam concentrate.
Carbon dioxide based fire extinguishers:
Although carbon dioxide has limited
effectiveness on chlorosilanes fire, it can be
used.
•
Two to three times as much carbon dioxide is
required to fight a chlorosilane fire as would be
required for a hydrocarbon fire of the same size.
AV11393
•
The most effective material for extinguishing chlorosilane
fires is aqueous foam.
12
Health and Safety
•
On a trichlorosilane or methyldichlorosilane
spill or fire, hydrogen could be trapped
beneath the foam blanket. Use caution with
the foam blanket.
•
On a fire involving chlorosilanes, a significant
amount of corrosive vapors will be released.
Foam helps hold these vapors down, but foam
will be consumed; continued application will be
necessary as the foam blanket breaks down.
•
Apply foam as gently as possible. Do not
“plunge” or aim foam streams directly into the
chlorosilane; this technique results in a severe
reaction between the chlorosilane and the
water contained in the foam solution.
•
Whenever possible, aim foam streams in front
of the chlorosilane or bounce the stream off
fixed objects (such as tanks or dike walls) to
allow the foam to flow gently onto the liquid
surface. It may occasionally be necessary to
“lob” foam to deliver it to the center of a fire.
•
Except in the case of very small fires, use
at least two nozzles whenever possible to
enhance distribution of the foam over the
surface of the chlorosilane.
•
Establish a relatively thick blanket of foam
(12” to 18” minimum) over the entire liquid
surface. Once this blanket has been laid,
temporarily suspend foam application to allow
extinguishment to occur.4 Reapply foam when
the intensity of the fire or the evolution of
smoke or vapors appears to stabilize or even
increase. Repeat this process as often as
necessary until extinguishment occurs or until
other emergency measures can be initiated.
•
Use extreme caution when applying foam and
when approaching the fire area. The hydrolysis
layer formed in the extinguishment process can
trap flammable vapors. If this layer is disturbed (by
impinging foam stream, for example) subsurface
ignitions and rapid flashovers may occur.
For more information on chlorosilane firefighting
techniques, see Manual on Chlorosilane
Emergency Response Guidelines, ASTM5 manual
series: MNL 33.
Health and Safety
Fixed fire protection
Despite the reactivity of chlorosilanes with water,
water sprinkler systems are the most effective
means of protecting buildings, equipment and building contents from chlorosilane fires. Foam-water
sprinkler systems using alcohol-compatible foam
can also be used to provide additional extinguishing
capabilities.
In tank farms and other areas where spilled chlorosilane would be relatively confined, a permanently
installed, medium-expansion foam system can be
provided to extinguish chlorosilane fires.
An adequate number of hydrants and, where appropriate, monitor nozzles, should be provided wherever
chlorosilanes are stored, handled or processed.
Adequate spill facilities are critical to safely drain
burning chlorosilanes and prevent other important
areas and property from exposure to a fire. Diking, curbs, sloped surfaces, drainage trenches and
remote impounding areas may be used. Spill control
facilities should be designed to accommodate the
largest anticipated release of chlorosilane as well as
the quantity of water expected from firefighting operations (including sprinkler systems, hoses, monitor
nozzles, etc.).
Additional fire protection features that may be warranted include (but are not limited to) the following:
•
Water supplies of sufficient capability and
duration.
•
Fire proofing of structural steel and steel
supporting vessels and equipment.
•
Explosion-relief panels and explosion-resistant
construction.
•
Fire walls with fire doors and dampers.
•
Vapor detection systems.
•
Fire detection and alarm systems.
Specific details can be found elsewhere in this guide,
as well as in various NFPA standards such as NFPA
10, 13, 15, 16, 20, 58, 72, 80, etc.) Users should
become familiar with these fire protection features
and standards.
It is theorized that the fire is extinguished as a result of the gradual hydrolysis of the chlorosilane by the water
draining from the foam. This hydrolysis reaction forms a layer of siloxane (fluid or gel) on the surface of the
chlorosilane, which inhibits vapor production and excludes oxygen, thereby extinguishing the fire.
4
This manual is available from ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959. Phone: (610)
832-9500.
5
13
Health and Safety
Health and Safety
All fire protection should be designed and installed
in accordance with government requirements and
according to NFPA or other recognized standards.
Instability and reactive hazards
Chlorosilanes are stable in the absence of air, moisture and catalytic agents. They do not decompose
appreciably when heated to 300˚C (572˚F) for short
periods.
Catalysts that may cause decomposition and rearrangement include bases, Lewis acids (such as
aluminum chloride and iron chloride) and anhydrous
bases (such as Grignard reagents, organoalkali
compounds and metal hydrides). When it is necessary to mix hydrochlorosilanes with such reagents,
allow for the formation of hydrogen and other
gases.
Chlorosilanes react with air (if moist or humid), water and a number of other compounds.
Air
Chlorosilanes, except for silicon tetrachloride, are
flammable or combustible and can form explosive
mixtures with air. Moisture in air causes hydrolysis
and the generation of hydrogen chloride fumes.
Water
Water reacts vigorously with chlorosilane, forming large volumes of hydrogen chloride. SiH-containing chlorosilanes such as trichlorosilane and
methyldichlorosilane can also produce hydrogen
when reacted with water. Hydrogen can further
be generated when hydrogen chloride reacts with
some metals.
Alcohols
Primary alcohols react with chlorosilanes almost as
rapidly as does water, forming hydrogen chloride.
Secondary and tertiary alcohols react less rapidly.
Ammonia and amines
Ammonia and aliphatic amines react rapidly with
chlorosilanes to generate heat, but NH4Cl typically
forms without the evolution of hydrogen chloride.
14
Bases
Bases react violently with chlorosilanes, generating
heat and potentially generating hydrogen (if SiH is
present) and carbon dioxide.
Chlorine
Chlorine reacts violently with any hydrogen-containing chlorosilane.
Engineering
Health and Safety
Waste disposal and spill containment
AV11394
Disposal of chlorosilanes is regulated by the RCRA
(Resource Conservation Recovery Act). Chlorosilanes with a flash point below 140˚F are classified as
D001 (ignitable) for disposal purposes. Several chlorosilanes may also be classified as D002 (corrosive)
and D003 (reactive) when discarded; refer to 40
CFR Part 261 for additional detail. It is important to
review the MSDS to determine all applicable federal
hazardous waste codes when considering disposal
of chlorosilanes. State and local regulations may
impose additional requirements for disposal.
A spill containment basin is used to hold spilled product
and treat it prior to disposal.
(basic) solution such as lime, soda ash, or
caustic. (See the following section, Special
Handling Procedures for SiH-Containing
Chlorosilanes.) To prevent the evolution of
acidic vapor, the quantity of water or alkaline
solution must be sufficient to absorb all the
hydrogen chloride that will be formed. The ratio
of water to chlorosilane should be more than
5 to 1 by volume, and the materials should be
mixed by an agitator or pump loop during the
addition step.
Disposal methods
•
•
•
The recommended disposal practice for
chlorosilanes is incineration. A facility must
hold an RCRA permit to treat or incinerate
hazardous wastes. Facilities of this type are
equipped with emission controls capable
of handling silicon dioxide particulates and
hydrogen chloride.
Because routine treatments and disposal
require permits or specific exemptions
under the RCRA, customer treatment and
disposal should be limited to emergencies or
nonroutine situations. Specialized equipment
is also necessary to conduct treatment of
chlorosilanes.
Chlorosilanes react with water. The reaction
is exothermic and vigorous and will result in
the evolution of corrosive hydrogen chloride
vapors as well as some silanol, hydrogen
gas (in the case of SiH) and small amounts
of polymer. Chlorosilanes must never be
discharged directly to surface water or
sewer systems. Treatment to dispose of
most chlorosilanes can be accomplished by
controlled introduction into water (hydrolysis)
or neutralization with an aqueous alkaline
•
The exothermic and corrosive nature of the
reactions should be considered in selecting
materials for the equipment used in
this procedure.
•
Adequate ventilation also should be provided to
handle any vapor evolution in a safe manner.
•
The rate of chlorosilane addition should be
controlled to permit instantaneous absorption
or neutralization of the resulting acid without
evolving acidic vapor to the atmosphere.
If acidic vapor is evolved, the addition of
chlorosilane should be halted to permit
absorption of the corrosive vapor into an
aqueous form.
•
The final reaction products are either an
aqueous acidic or neutralized silicone residue
mixture, depending on whether an alkaline
agent was used in the hydrolysis reaction.
The acidic water requires neutralization prior
to discharge to a private or municipal sewer
15
Health and Safety
system. (Review WWTP requirements prior
to discharge.) Residual acid and chlorosilane
may be entrained in the residue, which may
require additional treatment prior to disposal.
•
packaged and disposed of in compliance with
applicable regulations.
•
Hydrogen chloride vapors resulting from a
large spill can be reduced by means of a
water spray into the acid plume, being careful
not to spray water directly into the spilled
liquid chlorosilane pool. The resulting acidic
wastewater requires neutralization prior
to discharge to a municipal sewer system,
subject to applicable regulations.
•
For a large spill, contain the spill using dry
materials to prevent further runoff; then cover
with foam as described in the section of this
guide entitled Fire Hazards and Protection.
•
For silicon tetrachloride, foam is the preferred
fume-suppression agent. If foam is not
available, number 2 diesel fuel may be used
over the silicon tetrachloride spill. Repeated
application of the material should be used to
maintain the “blanket.” Reapplication will be
required until the chlorosilane can be removed
from the spill area.
•
In the event of an accidental spill of
chlorosilane to surface waters or to a municipal
sewer system, promptly notify the appropriate
pollution control agencies. Any release of
chlorosilane to the environment may require
reporting under Superfund regulations,
because these materials are listed under the
legislation as extremely hazardous substances.
Residue should be washed or neutralized to
remove residual acid. Neutralized silicone
residue should be disposed of by incineration
or fuel blending. Dow Corning does not
recommend landfilling of residual materials.
Special Handling Procedures for SiH
Containing Chlorosilanes
The disposal of reactive SiH-containing chlorosilanes (RCRA Waste Code D003) should be conducted with particular care due to the potential generation of hydrogen gas. Hydrogen gas is extremely
flammable and can cause a rapid pressure build-up
unless properly vented.
SiH-containing chlorosilanes should be first hydrolyzed with water only. This minimizes the potential for
hydrogen generation. The resultant reaction mixture
can then be further treated to safely neutralize it.
Containing spills
An accidental spill or release of chlorosilane results
in a hydrogen chloride vapor fog, which should be
minimized or controlled as quickly as possible.
Proper personal protective equipment offering skin,
eye and respiratory system protection is required.
Fully encapsulating vapor-protective clothing (level
A) is required for individuals who must work in a
chlorosilane vapor cloud. Dow Corning does not
recommend entering the vapor cloud generated by
dichlorosilane. When choosing protective clothing,
consider the fire hazard that may be associated with
the vapor cloud. Use of a flash suit over the level A
suit is recommended if a fire is possible.
•
In the case of a small spill of up to 4 liters
(one gallon), absorb the spill with sodium
bicarbonate, slaked lime or soda ash.
•
Scoop the mixture into a pail or open pan,
add a small amount of water, gently agitate
the mixture and let stand until the reaction is
complete. Continue to add small amounts of
water and mix until no reaction occurs. The
resulting material should then be properly
10
16
For more information on containing chlorosilane
spills, see Manual on Chlorosilane Emergency Response Guidelines, ASTM manual series: MNL 33.10
This manual is available from ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959. Phone: (610) 832-9500.
Engineering
5. Engineering
Building design
Process installations should ideally be built outdoors. Chlorosilanes are best processed in open
structures that provide good access for mobile
firefighting equipment.
•
The structure of the building should have a
permanent reliable bonding and grounding
system that meets appropriate codes.
•
The surfaces of equipment and building
structures should be covered with a protective
coating that will withstand accidental
chlorosilane exposure.
•
Eyewashes and safety showers should be
located in appropriate locations. Dow Corning
recommends placement of one eyewash/
safety shower within 50 ft of a location where
exposure to chlorosilane is possible. In storage
areas, this distance is increased to 100 ft.
Where possible, two accessible safety showers
are recommended in case a vapor cloud
renders one unusable.
•
Personnel evacuation routes or means of
egress should be planned and practiced. It
may be desirable to place emergency air packs
or other escape equipment designed for short
term use in the building.
Storage vessels should also be located outdoors,
remote from buildings and other facilities such as
overhead utilities and process piping. All spills should
be contained in a safe location and diverted from municipal sewer systems and natural waterways.
Firewalls may be necessary for the isolation of
larger volumes of chlorosilane when outdoor storage is not possible.
When it is necessary to handle chlorosilanes
within buildings:
•
All rooms should be provided with exhaust
ventilation at floor level, because chlorosilane
vapors are denser than air.
•
•
Sprinkler protection of adequate hydraulic
design and other means of fire protection
should be incorporated in the building or open
structure.
Equipment design
The design of piping and equipment for chlorosilanes is highly specialized because of the flammable and corrosive properties of these materials.
Special concerns are mentioned in this and following sections. However, equipment design, adequate
ventilation, and formulation of operating procedures
for ensure maximum security and economy are best
handled by experienced engineers and safety and
fire protection specialists.
The structure containing flammable
chlorosilanes should be made of
noncombustible materials. Exterior walls of
enclosed buildings may warrant explosion
relief panels.
AV11402
Process Vents
The proper design of buildings in which chlorosilanes are
handled and used is critical.
•
Before introducing a chlorosilane, it is important
to use totally enclosed systems. Atmospheric
openings or vents allow moisture to enter the
system, causing the generation of hydrogen
chloride, which will attack the equipment.
•
Use only dry, inert gas, such as nitrogen,
for any of the following tasks: pressurizing
vessels, priming pumps, blanketing tanks,
and filling or withdrawing tank contents. Verify
drying and inerting before adding chlorosilane.
•
Operational vents from inert gas blanketing
systems should be directed to a vent recovery
system, a vent scrubber, or both.
17
AV11330
Engineering
•
All vessels must have emergency vents and
should otherwise satisfy the requirements
stated in “Flammable and Combustible Liquids
Code,” NFPA No. 30, latest edition.
•
Vessels should be equipped with pressurerelief valves to relieve excess internal pressure
related to fire or other causes.
•
A nonfragmenting-type rupture disk should be
used ahead of the relief valve on chlorosilane
storage vessels; otherwise, the valve can be
clogged with hydrolysis products resulting from
chlorosilane contact with moisture in air.
•
“Rain hats” should be used over the
ends of vent pipe outlets. The publication
Recommended Practice for the Design and
Installation of Pressure-Relieving Systems in
Refineries, Part II, Installation,6 should be used
as a guide for emergency vent installations.
•
Vessel supports should be made of reinforced
concrete or structural steel protected by fireprotective coatings.
All chlorosilane vessels must satisfy the requirements stated in
"Flammable and Combustible Liquids Code," NFPA No. 30, latest edition.
Construction materials
•
In the absence of water, carbon steel is
satisfactory for piping and other equipment
used to contain chlorosilanes.
•
Never use nonferrous metals and alloys
such as aluminum, bronze, copper, zinc or
magnesium. These materials are more readily
corroded, and many have low melting points,
which could be hazardous in case of fire.
•
Due to its brittleness, cast iron must not be
used to contain chlorosilanes; however cast
steel and forged steel can be used.
•
Stainless steel can be used for purity reasons
or for low temperature service.
•
All equipment and piping, including stainless
steel, must be painted to avoid external corrosion.
Piping
•
All piping should be made of American
Society for Testing and Materials (ASTM)
grade materials suitable for the pressure and
temperature limitations given in the American
National Standards Institute (ANSI) publication
ANSI B31.3, Chemical Plant and Petroleum
Refinery Piping Code.
•
Seamless carbon steel piping, such as ASTM
A-106 (Grade B) or A-53 (Grade B) is
recommended.
•
Welded and flanged piping connections
are preferable for maintaining a leak-tight
system. Socket-weld or butt-weld fittings
in conjunction with raised-face flange
connections are satisfactory. Threaded piping
up to 0.75” diameter may be used; use flanged
connections for larger sizes.
•
Where it is necessary to use threaded
connections, heavier wall pipe should be used
to allow for pipe wall thickness reductions.
Teflon™7 tape or paste and graphoil tape have
been found to be good thread seal materials.
Always select Teflon tape, never paste, when
purchasing an electronic or fiber-optic grade
material. Paste may contribute electronic
impurities to the product.
Vessels
•
•
18
Storage vessels should be designed and
fabricated in accordance with the American
Society of Mechanical Engineers (ASME)
Code, Section VIII, for a minimum of 345 kPa
gauge (50 psig) internal pressure and for full
vacuum.
For storage of trichlorosilane, or when
designing a pump transfer out of the tank truck
for any chlorosilane product, the recommended
maximum allowable working pressure of the
storage tank should be a minimum of 75 psig
with full vacuum capability.
6
American Petroleum Institute, latest edition.
7
Trademark of E. I. Du Pont de Nemours & Co.
Engineering
•
Fire shut-off valves are recommended for
bottom connections on vessels. These valves
should be remotely controlled or fail closed in
case of fire exposure.
•
The interconnection of portable containers or
permanent piping can be made with swing-arm
rotary joints or seamless, braided flexible metal
hose. Flanged or union connections should be
used; do not use quick disconnect couplings.
•
Modulating control valves with stainless steel
bellow seals are recommended to prevent
leakage to the atmosphere.
•
Stainless steel diaphragm pressure switches
and pressure and differential pressure
transmitters are recommended.
•
A high-level alarm is recommended for level
indication on all vessels. In addition, processactivated high-level alarms are recommended.
These alarms should be interlocked to a
process shutdown switch.
•
Flange connections are recommended to
minimize possible leak paths.
•
The use of braided flexible hose must be
properly managed in specific areas of size,
length, materials of construction, pressure
rating and compatibility.
•
Installed hose should be inspected and
pressure checked prior to each use. Hose
should be replaced at a specified time and
protected when not in use.
•
The typical hose in chlorosilane service at
Dow Corning USA for flexible connections to
tank trucks or railcars is a braided flex hose,
which consists of a 400 Monel, single-braid
exterior reinforcement over a Monel 400,
heavy-wall, inner-corrugated seamless hose
(Senior Flexonics).
•
Remote shut off valving should be incorporated
at each end of the hose.
•
End connections are 316 SS stub ends with
ANSI 150 pound class, carbon steel, raisedface flanges or welded male 316 SS NPT hex
collar on the other end. Flanged ends are
recommended for hose 2 inches in diameter
and larger.
Pumps
•
Pump selection should be based on the best
features against leakage to the atmosphere.
•
Canned pumps and AVS chemical
standard pumps with mechanical seals
are recommended. However, only canned
pumps should be used for trichlorosilane and
methyldichlorosilane.
Instrumentation
•
Instrument Society of America (ISA)
standards and practices for instrumentation
are recommended.
AV11347
Hoses
Enclosed process buildings should be well ventilated
Ventilation
Enclosed processing buildings should be ventilated
at a rate of not less than 5 liters/sec for each square
meter (1 ft3/min for each square foot) of solid floor
area for the first floor and all upper floors. Threshold
limit values for HCl and O2 should be satisfied. If
mechanical ventilation is used, the electrical equipment should meet NEC requirements.
Electrical equipment
All electrical equipment should conform to the NEC
as set forth in Subpart S of the OSHA Regulations
29 CFR, Section 1910.309. In addition, the following instructions should be met:
•
Area classifications should be established for all
areas in which chlorosilanes or other flammable
materials are handled or stored. Dow Corning
recommends that NFPA 497A be used as a
basis for establishing these classifications.
19
Engineering
Engineering
To drain static charges and avoid spark
discharges, a continuous path from the point
of generation to ground should be provided.
This is best accomplished by electrically
interconnecting (bonding) all vessels and
piping and grounding all vessels and piping.
•
Bonds or grounds for static protection may
be of any conductor size. A ground size for
power or lightning protection is typically more
than adequate for grounding static electricity.
However, ground wiring should be of sufficient
size to provide reasonable protection against
physical wear. Periodic checks of continuity
to ground should be made. All fixed and all
portable containers should be effectively
grounded and bonded.
AV11331
•
Vapor-tight or corrosion-resistant electrical equipment is recommended
for areas in which chlorosilanes are stored or handled.
Caution: Tanks and reactors may be coated on
the interior with a nonconductive coating. This
coating reduces the effectiveness of any external connection to ground. Therefore, in addition
to bonding and grounding, containers or equipment should be purged with dry nitrogen before
filling with a flammable chlorosilane.
In general, chlorosilanes are Group C or D
materials, depending on the characteristics of
the specific chlorosilane. Electrical equipment
should comply with the requirements of
Article 500 of the NEC for the classifications
established.
•
In areas where silicon tetrachloride is the only
chlorosilane present and no other flammable
materials are present, the area may be
considered “nonhazardous” as defined by
Article 500 of the NEC.
•
Dow Corning recommends that vapor-tight or
corrosion-resistant electrical equipment be
used due to the corrosive nature of areas in
which chlorosilanes are stored or handled.
Static electricity
Static electricity discharges can ignite flammable
chlorosilane vapor. The API Bulletin Protection
Against Ignition Arising Out of Static Lightning and
Stray Currents8 and the NFPA publication Recommended Practice on Static Electricity9 are useful
guides for solving static electricity problems.
•
Static electricity may be generated when
any of these compounds flow through or are
discharged from a pipe or fall freely through
space. Splash filling is particularly hazardous
and should be avoided.
•
20
•
Fill lines should be conductively bonded to
provide a path to ground outside the container.
Dow Corning recommends that the connection
between the filing vessel and the unloading
line be checked for continuity prior to beginning
the unloading procedure.
•
Tanks filled through top connections should
have dip lines extending to within 15 cm (6
in) of the bottom of the container. Such pipes
should include a siphon break.
•
Static conductive V-belts should be used
whenever a belt drive is used.
Preparing new equipment
Filling velocities of tanks should be kept below
1 m/sec (3 ft/sec) in the fill pipe until the end of
the pipe is covered by liquid.
•
Thoroughly dry equipment such as lines,
pumps, valves, and vessels. There should be
no remaining traces of water.
•
Test the system for leaks at or above operating
pressure with helium or a dry, inert gas. Paint
each joint with soap solution and check for
bubbles. If you can use helium as the inert gas,
you can use a helium detector to check for leaks.
8
American Petroleum Institute Bulletin, RP 2003, 1974
9
NFPA No. 77
Containers
Containers
6. ContainersGeneral handling
Shipping, marking, labeling and placarding
Chlorosilanes are classified as hazardous materials
by the Department of Transportation (DOT) and the
International Maritime Dangerous Goods (IMDG)
Code, and they are regulated in all modes of transportation. Shippers should refer to 49 CFR and/or
IMDG Code for classification, containers and shipping information. The burden of assigning proper
hazard classification, container selection, marking,
labeling, placarding and shipping documentation
falls on the shipper.
AV11381
Some chlorosilanes are not currently classified as
Dangerous When Wet (DWW) in 49 CFR. Hydrogen chloride is a toxic gas and is evolved when
chlorosilanes come into contact with water. Under
some conditions, the rate of evolution of HCl from
these chlorosilanes is sufficient for them to fall into
the DWW classification. This issue was presented
to the Department of Transportation by the Silicones
Environmental Health and Safety Council (SEHSC).
The DOT has approved the following procedure for
classifying chlorosilanes.
Note special DWW Placard/Label as shown.
All chlorosilanes not already classified as DWW
(due to SiH content) are to be given a subsidiary
DWW classification for domestic shipment, and the
DWW placard/label is to be displayed on all packages. In addition, the wording “emits toxic gas
when wet” is to be displayed adjacent to the DWW
placard/label.
Also, at the request of the SEHSC, the DOT has
issued a letter of “Competent Authority Approval”
that changes the Primary Hazard Classification for
silicon tetrachloride and n-propyltrichlorosilane from
“Corrosive” (Class 8) to “Toxic” (Class 6, Division
6.1). For shipments within the U.S., Canada and
Mexico, silicon tetrachloride and n-propyltrichlorosilane will be placarded/labeled with a Primary
Hazard of 6.1. It is anticipated that this change may
impact a limited number of additional chlorosilanes
in the near future.
AV11363
Empty containers (tank trucks, tank cars and portable tanks that previously contained chloro-silanes
and have not been cleaned) must be shipped in
compliance with applicable regulations as found in
49 CFR and/or the IMDG Code.
The shipper is responsible for proper hazard classification,
container selection, shipping documentation and proper
marking, labeling and placarding.
Just as they are regulated for shipping, chlorosilanes are also subject to marking, labeling and placarding requirements according to 49 CFR and/or
the IMDG Code.
Containers of hazardous chemicals, including each
member of the chlorosilane family, must carry a label
21
Containers
Containers
SiH-containing chlorosilanes such as trichlorosilane
and methyldichlorosilane. In this case, oxygen content should be less than 2 percent.
Note: These concentrations provide a safety margin
at least 50 percent below the minimum oxygen concentration necessary for ignition to occur.
Only qualified, fully trained and experienced employees should sample, connect, load, unload or
disconnect any container of chlorosilanes.
AV11396
It is crucial to wear proper protective clothing and
use protective equipment during connecting, loading, unloading and disconnecting operations. An
emergency shower and eyewash station should be
provided within 8 to 15 meters (25 to 50 feet) of the
loading or unloading area. Test the shower fountain
before loading or unloading.
Easy access to an emergency shower
is a critical safety feature of loading
and unloading areas.
or suitable marking that meets OSHA requirements
according to 29 CFR 1910. This label or marking
serves as a precautionary warning to workers.
Container handling
In this section, a container refers to portable tanks,
tank trucks or tank cars. The use of these containers must be authorized by the DOT. To determine
authorized containers for a specific chlorosilane,
refer to 49 CFR. For transportation by ocean, the
container must also be authorized by the International Maritime Organization’s IMDG Code.
Federal, state and local rules, regulations and
ordinances governing loading must be observed.
No container should be completely filled; adequate
outage or vapor space for product expansion must
be determined and provided.
The oxygen content of containers to be filled should
be less than 4 percent for all chlorosilanes except
22
All tools and equipment (e.g., fittings, pumps and
hoses) should be suited for use with chlorosilanes.
This equipment should be used only for chlorosilanes, kept free of moisture or other contaminants,
and properly protected against mechanical damage.
At all times, valves and the interior and exterior of
the protective valve housings should be kept clean
and free of contaminants, gels or gel-like material
caused by the reaction of these materials with water.
Container selection
This section was designed to help Dow Corning
customers select the best container for their current
or future business. Information most often requested by customers is included here.
State and local requirements for handling these hazardous materials must be considered. Dow Corning frequently finds such requirements to be an issue when
reviewing customers’ understanding of chlorosilane
handling.
The following container options are available from
Dow Corning. Not all chlorosilanes are available in
all containers. Before making a selection, customers should check with Dow Corning to determine
available options for specific materials.
Containers
Containers
DOT/AAR classification: 105 S 500W tank car
(pressure car).
•
DOT classification: MC-331 tank truck
(pressure vessel).
•
Owner/lessor: Dow Corning Corporation
•
Owner/lessor: Dow Corning Corporation
•
Capacity, full: 17,300 gal (assume 10%
outage loaded).
•
Capacity, full: 4,800 gal (assume 10%
outage loaded).
•
Average tare weight: 82,300 lb.
•
•
Maximum weight on rails: 263,000 lb.
Average tare weight: 34,000 lb (tractor and
tank truck).
•
Product transfer: top load/unloading only.
•
Maximum weight on road: 80,000 lb (tractor,
tank and product).
•
Average transit time: 7 - 10 days.
•
•
Typical operation: product transferred into
customer-specified storage tank.
Product transfer: ground access, rear
load/unloading.
•
Average transit time: 1 - 3 days, depending
on destination.
•
Typical operation: product transferred into
customer-specified storage tank.
AV11398
AV11400
AV11397
•
AV# 11399
Domestic tank truck (USA)
Tank car (USA)
Employees responsible for loading or unloading tank cars must be fully trained regarding the features
and operation of these containers, and they must carefully observe all safety precautions.
23
Containers
Containers
Portable tank (large)-Domestic and International
•
IMO/DOT classification: IMO-1/DOT51 portable
tank (pressure vessel).
•
Owner/lessor: Dow Corning Corporation
•
Capacity, full: 4,200 or 4,600 gal (assume 10%
min & 20% max outage loaded).
•
Average tare weight: 38,000 lb (tank, chassis
and tractor).
•
Maximum weight on road: 80,000 lb (USA;
tank, chassis, tractor and product).
•
Product transfer: top load/unloading only.
•
Average transit time: USA to overseas: 20
days.
•
Typical operation: product transferred into
customer-specified storage tank.
•
IMO/DOT classifications IMO-1/DOT51
portable tank
•
If built after 2003, now a UN portable tank
•
Owner: customer purchase through
Dow Corning program.
•
Capacity, full: 120 gal, fill capacity
approximately 100 gal (15% outage).
•
Average tare weight: 450 lb.
•
Maximum weight: designed for products up to
1.5 specific gravity.
•
Product transfer: top load/unloading only.
•
Average transit time: domestic 7 - 10 days,
international approximately 20 days.
•
Typical operation: product transferred into
customer-specified storage tank or as feed
tank process (pending state approval).
Portable tank (small) -Domestic and International
DOT classification: DOT51 portable tank
(pressure vessel).
24
AV11389
AV11360
Portable tanks range in size from small (120 gallons) to large (4,600 gallons).
AV11381
Note: for
international use,
tank must receive
country approval
prior to any intended
shipment, arranged
with Dow Corning
site or customer.
AV11356
•
Containers
For more information
We hope the preceding container information has
helped narrow the options for your specific needs. We
recognize this is a first step; a more detailed brochure
and video are available for each container type. The
brochure includes valve and pipe sizes, generic
layout and many more container-specific details. To
obtain this information, please contact Dow Corning’s
Customer Service Group at 1-800-248-2481 and
request it by container name.
Containers
Dow Corning is committed to serving your product
needs, and we look forward to a safe and long business relationship.
The information and data contained herein are
based on information we believe reliable. You should
thoroughly test any application and independently
conclude satisfactory performance before commercialization. Suggestions of uses should not be taken
as inducements to infringe any particular patent.
Appendix
International regulations
Regulation
IATA - International Air Transport Association
IMO - International Maritime Organisation
IMDG – International Maritime Dangerous Goods
ASTM - American Society for Testing and Materials
ASME – American Society of Mechanical Engineers
National regulations
Health & Safety / Distribution & Transportation
Area
Regulation
USA
National Electric Code (NEC)
NFPA (National Fire Protection Association)
Code of Federal Regulations (CFR)
Department of Transport (DOT)
Europe
ATEX (Explosive Atmosphere)
ADR Regulations: European Agreement Concerning the International carriage of Dangerous
Goods by Road
RID Regulations: European Agreement Concerning the International carriage of Dangerous
Goods by Rail
Department for Transport (DfT)
Mexico
Brazil
China
India
Japan
25
LIMITED WARRANTY INFORMATION - PLEASE READ CAREFULLY
The information contained herein is offered in good faith and is believed to be accurate. However,
because conditions and methods of use of our products are beyond our control, this information should
not be used in substitution for customer’s tests to ensure that Dow Corning’s products are safe, effective,
and fully satisfactory for the intended end use. Suggestions of use shall not be taken as inducements to
infringe any patent.
Dow Corning’s sole warranty is that the product will meet the Dow Corning sales specifications in effect
at the time of shipment.
Your exclusive remedy for breach of such warranty is limited to refund of purchase price or replacement
of any product shown to be other than as warranted.
DOW CORNING SPECIFICALLY DISCLAIMS ANY OTHER EXPRESS OR IMPLIED WARRANTY OF
FITNESS FOR A PARTICULAR PURPOSE OR MERCHANTABILITY. DOW CORNING DISCLAIMS
LIABILITY FOR ANY INCIDENTAL OR CONSEQUENTIAL DAMAGES.
DOW CORNING is a registered trademark of Dow Corning Corporation.
WE HELP YOU INVENT THE FUTURE is a trademark of Dow Corning Corporation.
©2008 Dow Corning Corporation. All rights reserved.
Cover Photo: AV11403
Printed in USA
VIS2558
Form No. 01-4012-01