SULFUR TRIOXIDE
The
Chemical Identifier fields
include common identification numbers, the
NFPA diamond
U.S. Department of Transportation hazard labels, and a general
description of the chemical. The information in CAMEO Chemicals comes
from a variety of
data sources.
CAS Number | UN/NA Number |
---|---|
|
|
DOT Hazard Label | USCG CHRIS Code |
|
none |
NIOSH Pocket Guide | International Chem Safety Card |
none |
NFPA 704
data unavailable
General Description
Sulfur trioxide, is a colorless to white crystalline solid which will fume in air. Often shipped with inhibitor to prevent polymerization. It reacts violently with water to form sulfuric acid with the release of heat. It is corrosive to metals and tissue. It causes eye and skin burns. Ingestion causes severe burns of mouth esophagus and stomach. The vapor is very toxic by inhalation. It is a fire risk when in contact with organic materials such as wood, cotton, fiberboard, etc.
The
Hazard fields
include
special hazard alerts
air and water
reactions, fire hazards, health hazards, a reactivity profile, and
details about
reactive groups assignments
and
potentially incompatible absorbents.
The information in CAMEO Chemicals comes from a variety of
data sources.
Reactivity Alerts
- Strong Oxidizing Agent
- Known Catalytic Activity
- Water-Reactive
Air & Water Reactions
Combines with water with explosive force, forming sulfuric acid. Sulfur trioxide chars most organic substances. On exposure to air it absorbs moisture rapidly, emitting dense white acidic fumes, mists [Merck 11th ed. 1989].
Fire Hazard
Fire risk in contact with organic materials. An explosive increase in vapor pressure occurs when the alpha form melts. Combines with water with explosive violence, forming sulfuric acid. May ignite other combustible materials (wood, paper, oil, etc.). Flammable poisonous gases may accumulate in tanks and hopper cars. Runoff to sewer may create fire or explosion hazard. Forms sulfuric acid on contact with water. Avoid water and organic materials. On exposure to air, it absorbs moisture and emits dense white fumes. (EPA, 1998)
Health Hazard
This material is highly toxic. It is an irritant and corrosive to mucous membranes. Poisonous if inhaled or swallowed. Contact causes severe burns to skin and eyes. (EPA, 1998)
Reactivity Profile
The reaction of SULFUR TRIOXIDE and oxygen difluoride is very vigorous and explosions occur if the reaction is carried out in the absence of a solvent [J. Chem. Eng. Data 13(4):529-531. 1968]. The reaction of sulfur trioxide in excess with tetrafluoroethylene causes explosive decomposition to carbonyl fluoride and sulfur dioxide [Chem. Eng. News 49(22):3. 1971]. The reaction of anhydrous perchloric acid with sulfur trioxide is violent and accompanied by the evolution of considerable heat (Pascal 16:300 1931-34). Liquid sulfur trioxide reacts violently with nitryl chloride, even at 75°C. The reaction of sulfur trioxide and lead oxide causes white luminescence [Mellor 7:654 1946-47]. The combination of iodine, pyridine, sulfur trioxide, and formamide developed a gas over pressurization after several months. This is due to the slow formation of sulfuric acid, from external water or dehydration of the formamide to hydrogen cyanide.
Belongs to the Following Reactive Group(s)
Potentially Incompatible Absorbents
Use caution: Liquids with this reactive group classification have been known to react with the absorbents listed below. More info about absorbents, including situations to watch out for...
- Cellulose-Based Absorbents
- Expanded Polymeric Absorbents
The
Response Recommendation fields
include isolation and evacuation distances, as well as recommendations for
firefighting, non-fire response, protective clothing, and first aid. The
information in CAMEO Chemicals comes from a variety of
data sources.
Isolation and Evacuation
Excerpt from ERG Guide 137 [Substances - Water-Reactive - Corrosive]:
IMMEDIATE PRECAUTIONARY MEASURE: Isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters (75 feet) for solids.
SPILL: See ERG Table 1 - Initial Isolation and Protective Action Distances on the UN/NA 1829 datasheet.
FIRE: If tank, rail tank car or highway tank is involved in a fire, ISOLATE for 800 meters (1/2 mile) in all directions; also, consider initial evacuation for 800 meters (1/2 mile) in all directions. (ERG, 2024)
IMMEDIATE PRECAUTIONARY MEASURE: Isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters (75 feet) for solids.
SPILL: See ERG Table 1 - Initial Isolation and Protective Action Distances on the UN/NA 1829 datasheet.
FIRE: If tank, rail tank car or highway tank is involved in a fire, ISOLATE for 800 meters (1/2 mile) in all directions; also, consider initial evacuation for 800 meters (1/2 mile) in all directions. (ERG, 2024)
Firefighting
Keep unnecessary people away; isolate hazard area and deny entry. Stay upwind; keep out of low areas. Ventilate closed spaces before entering them. Wear positive pressure breathing apparatus and special protective clothing.
Do not get water inside container. Small fires: dry chemical or carbon dioxide. Large fires: flood fire area with water from a distance. Do not get solid stream of water on spilled material. Move container from fire area if you can do so without risk. Spray cooling water on containers that are exposed to flames until well after fire is out. (EPA, 1998)
Do not get water inside container. Small fires: dry chemical or carbon dioxide. Large fires: flood fire area with water from a distance. Do not get solid stream of water on spilled material. Move container from fire area if you can do so without risk. Spray cooling water on containers that are exposed to flames until well after fire is out. (EPA, 1998)
Non-Fire Response
Excerpt from ERG Guide 137 [Substances - Water-Reactive - Corrosive]:
Do not touch damaged containers or spilled material unless wearing appropriate protective clothing. Stop leak if you can do it without risk. Use water spray to reduce vapors; do not put water directly on leak, spill area or inside container. Keep combustibles (wood, paper, oil, etc.) away from spilled material.
SMALL SPILL: Cover with DRY earth, DRY sand or other non-combustible material followed with plastic sheet to minimize spreading or contact with rain. Use clean, non-sparking tools to collect material and place it into loosely covered plastic containers for later disposal. Prevent entry into waterways, sewers, basements or confined areas. (ERG, 2024)
Do not touch damaged containers or spilled material unless wearing appropriate protective clothing. Stop leak if you can do it without risk. Use water spray to reduce vapors; do not put water directly on leak, spill area or inside container. Keep combustibles (wood, paper, oil, etc.) away from spilled material.
SMALL SPILL: Cover with DRY earth, DRY sand or other non-combustible material followed with plastic sheet to minimize spreading or contact with rain. Use clean, non-sparking tools to collect material and place it into loosely covered plastic containers for later disposal. Prevent entry into waterways, sewers, basements or confined areas. (ERG, 2024)
Protective Clothing
For emergency situations, wear a positive pressure, pressure-demand, full facepiece self-contained breathing apparatus (SCBA) or pressure- demand supplied air respirator with escape SCBA and a fully-encapsulating, chemical resistant suit. (EPA, 1998)
DuPont Tychem® Suit Fabrics
Tychem® Fabric Legend
QS = Tychem 2000 SFR |
QC = Tychem 2000 |
SL = Tychem 4000 |
C3 = Tychem 5000 |
TF = Tychem 6000 |
TP = Tychem 6000 FR |
RC = Tychem RESPONDER® CSM |
TK = Tychem 10000 |
RF = Tychem 10000 FR |
Testing Details
The fabric permeation data was generated for DuPont by a third party
laboratory. Permeation data for industrial chemicals is obtained per
ASTM F739. Normalized breakthrough times (the time at which the
permeation rate exceeds 0.1 μg/cm2/min) are reported in minutes. All
chemicals have been tested between approximately 20°C and 27°C unless
otherwise stated. All chemicals have been tested at a concentration of
greater than 95% unless otherwise stated.
Chemical warfare agents (Lewisite, Sarin, Soman, Sulfur Mustard, Tabun
and VX Nerve Agent) have been tested at 22°C and 50% relative humidity
per military standard MIL-STD-282. "Breakthrough time" for chemical
warfare agents is defined as the time when the cumulative mass which
permeated through the fabric exceeds the limit in MIL-STD-282 [either
1.25 or 4.0 μg/cm2].
A Caution from DuPont
This information is based upon technical data that DuPont believes to
be reliable on the date issued. It is subject to revision as additional
knowledge and experience are gained. The information reflects
laboratory performance of fabrics, not complete garments, under
controlled conditions. It is intended for informational use by persons
having technical skill for evaluation under their specific end-use
conditions, at their own discretion and risk. It is the user's
responsibility to determine the level of toxicity and the proper
personal protective equipment needed. Anyone intending to use this
information should first verify that the garment selected is suitable
for the intended use. In many cases, seams and closures have shorter
breakthrough times and higher permeation rates than the fabric. If
fabric becomes torn,abraded or punctured, or if seams or closures fail,
or if attached gloves, visors, etc. are damaged, end user should
discontinue use of garment to avoid potential exposure to chemical.
Since conditions of use are outside our control, DuPont makes no
warranties, express or implied, including, without limitation, no
warranties of merchantability or fitness for a particular use and
assume no liability in connection with any use of this information.
This information is not intended as a license to operate under or a
recommendation to infringe any patent, trademark or technical
information of DuPont or others covering any material or its use.
Chemical | CAS Number | State | QS | QC | SL | C3 | TF | TP | RC | TK | RF |
---|---|---|---|---|---|---|---|---|---|---|---|
Sulfur trioxide | 7446-11-9 | Liquid | imm | 90 | 90 | 90 |
"imm" indicates immediate; having a normalized breakthrough time of 10 minutes or less.
Special Warning from DuPont: Tychem® and Tyvek® fabrics should not be used around heat, flames, sparks or in potentially flammable or explosive environments. Only...
...Tychem® ThermoPro, Tychem® Reflector® and Tychem® TK styles 600T/601T
(with aluminized outer suit) garments are designed and tested to help
reduce burn injury during escape from a flash fire. Users of Tychem®
ThermoPro, Tychem® Reflector® and Tychem® TK styles 600T/601T (with
aluminized outer suit) garments should not knowingly enter an explosive
environment. Tychem® garments with attached socks must be worn inside
protective outer footwear and are not suitable as outer footwear. These
attached socks do not have adequate durability or slip resistance to be
worn as the outer foot covering.
(DuPont, 2024)
First Aid
Warning: Sulfur trioxide is extremely corrosive. Caution is advised.
Signs and Symptoms of Sulfur Trioxide Exposure: Signs and symptoms of acute ingestion of sulfur trioxide may be severe and include salivation, intense thirst, difficulty in swallowing, chills, pain, and shock. Oral, esophageal, and stomach burns are common. Vomitus generally has a coffee-ground appearance. The potential for circulatory collapse is high following ingestion of sulfur trioxide. Acute inhalation exposure of sulfur trioxide may result in sneezing, hoarseness, coughing, choking, laryngitis, and respiratory tract irritation. Bleeding of nose and gums, ulceration of the nasal and oral mucosa, bronchitis, pneumonia, dyspnea (shortness of breath), chest pain, and pulmonary edema and respiratory failure may also occur. Eye exposure to sulfur trioxide may result in irritation, pain, swelling, corneal erosion, and blindness. Dermal exposure may result in dermatitis (red, inflamed skin), severe burns, and pain.
Emergency Life-Support Procedures: Acute exposure to sulfur trioxide may require decontamination and life support for the victims. Emergency personnel should wear protective clothing appropriate to the type and degree of contamination. Air-purifying or supplied-air respiratory equipment should also be worn, as necessary. Rescue vehicles should carry supplies such as plastic sheeting and disposable plastic bags to assist in preventing spread of contamination.
Inhalation Exposure:
1. Move victims to fresh air. Emergency personnel should avoid self-exposure to sulfur trioxide.
2. Evaluate vital signs including pulse and respiratory rate, and note any trauma. If no pulse is detected, provide CPR. If not breathing, provide artificial respiration. If breathing is labored, administer oxygen or other respiratory support.
3. Obtain authorization and/or further instructions from the local hospital for administration of an antidote or performance of other invasive procedures.
4. Transport to a health care facility.
Dermal/Eye Exposure:
1. Remove victims from exposure. Emergency personnel should avoid self-exposure to sulfur trioxide.
2. Evaluate vital signs including pulse and respiratory rate, and note any trauma. If no pulse is detected, provide CPR. If not breathing, provide artificial respiration. If breathing is labored, administer oxygen or other respiratory support.
3. Remove and isolate contaminated clothing as soon as possible.
4. If eye exposure has occurred, eyes must be flushed with lukewarm water for at least 15 minutes.
5. Wash exposed skin areas thoroughly with soap and water.
6. Obtain authorization and/or further instructions from the local hospital for administration of an antidote or performance of other invasive procedures.
7. Transport to a health care facility.
Ingestion Exposure:
1. Evaluate vital signs including pulse and respiratory rate, and note any trauma. If no pulse is detected, provide CPR. If not breathing, provide artificial respiration. If breathing is labored, administer oxygen or other respiratory support.
2. DO NOT induce vomiting or attempt to neutralize!
3. Rinse mouth with large amounts of water. Inform victims not to swallow this water.
4. Obtain authorization and/or further instructions from the local hospital for administration of an antidote or performance of other invasive procedures.
5. Activated charcoal is of no value.
6. Give the victims water or milk: children up to 1 year old, 125 mL (4 oz or 1/2 cup); children 1 to 12 years old, 200 mL (6 oz or 3/4 cup); adults, 250 mL (8 oz or 1 cup). Water or milk should be given only if victims are conscious and alert.
7. Transport to a health care facility. (EPA, 1998)
Signs and Symptoms of Sulfur Trioxide Exposure: Signs and symptoms of acute ingestion of sulfur trioxide may be severe and include salivation, intense thirst, difficulty in swallowing, chills, pain, and shock. Oral, esophageal, and stomach burns are common. Vomitus generally has a coffee-ground appearance. The potential for circulatory collapse is high following ingestion of sulfur trioxide. Acute inhalation exposure of sulfur trioxide may result in sneezing, hoarseness, coughing, choking, laryngitis, and respiratory tract irritation. Bleeding of nose and gums, ulceration of the nasal and oral mucosa, bronchitis, pneumonia, dyspnea (shortness of breath), chest pain, and pulmonary edema and respiratory failure may also occur. Eye exposure to sulfur trioxide may result in irritation, pain, swelling, corneal erosion, and blindness. Dermal exposure may result in dermatitis (red, inflamed skin), severe burns, and pain.
Emergency Life-Support Procedures: Acute exposure to sulfur trioxide may require decontamination and life support for the victims. Emergency personnel should wear protective clothing appropriate to the type and degree of contamination. Air-purifying or supplied-air respiratory equipment should also be worn, as necessary. Rescue vehicles should carry supplies such as plastic sheeting and disposable plastic bags to assist in preventing spread of contamination.
Inhalation Exposure:
1. Move victims to fresh air. Emergency personnel should avoid self-exposure to sulfur trioxide.
2. Evaluate vital signs including pulse and respiratory rate, and note any trauma. If no pulse is detected, provide CPR. If not breathing, provide artificial respiration. If breathing is labored, administer oxygen or other respiratory support.
3. Obtain authorization and/or further instructions from the local hospital for administration of an antidote or performance of other invasive procedures.
4. Transport to a health care facility.
Dermal/Eye Exposure:
1. Remove victims from exposure. Emergency personnel should avoid self-exposure to sulfur trioxide.
2. Evaluate vital signs including pulse and respiratory rate, and note any trauma. If no pulse is detected, provide CPR. If not breathing, provide artificial respiration. If breathing is labored, administer oxygen or other respiratory support.
3. Remove and isolate contaminated clothing as soon as possible.
4. If eye exposure has occurred, eyes must be flushed with lukewarm water for at least 15 minutes.
5. Wash exposed skin areas thoroughly with soap and water.
6. Obtain authorization and/or further instructions from the local hospital for administration of an antidote or performance of other invasive procedures.
7. Transport to a health care facility.
Ingestion Exposure:
1. Evaluate vital signs including pulse and respiratory rate, and note any trauma. If no pulse is detected, provide CPR. If not breathing, provide artificial respiration. If breathing is labored, administer oxygen or other respiratory support.
2. DO NOT induce vomiting or attempt to neutralize!
3. Rinse mouth with large amounts of water. Inform victims not to swallow this water.
4. Obtain authorization and/or further instructions from the local hospital for administration of an antidote or performance of other invasive procedures.
5. Activated charcoal is of no value.
6. Give the victims water or milk: children up to 1 year old, 125 mL (4 oz or 1/2 cup); children 1 to 12 years old, 200 mL (6 oz or 3/4 cup); adults, 250 mL (8 oz or 1 cup). Water or milk should be given only if victims are conscious and alert.
7. Transport to a health care facility. (EPA, 1998)
The
Physical Property fields
include properties such as vapor pressure and
boiling point, as well as explosive limits and
toxic exposure thresholds
The information in CAMEO Chemicals comes from a variety of
data sources.
Note: For Vapor Density and Specific Gravity, comparing the value to 1.0 can tell you if the chemical will likely sink/rise in air or sink/float in fresh water (respectively). Short phrases have been added to those values below as an aid. However, make sure to also consider the circumstances of a release. The Vapor Density comparisons are only valid when the gas escaping is at the same temperature as the surrounding air itself. If the chemical is escaping from a container where it was pressurized or refrigerated, it may first escape and behave as a heavy gas and sink in the air (even if it has a Vapor Density value less than 1). Also, the Specific Gravity comparisons are for fresh water (density 1.0 g/mL). If your spill is in salt water (density about 1.027 g/mL), you need to adjust the point of comparison. There are some chemicals that will sink in fresh water and float in salt water.
Note: For Vapor Density and Specific Gravity, comparing the value to 1.0 can tell you if the chemical will likely sink/rise in air or sink/float in fresh water (respectively). Short phrases have been added to those values below as an aid. However, make sure to also consider the circumstances of a release. The Vapor Density comparisons are only valid when the gas escaping is at the same temperature as the surrounding air itself. If the chemical is escaping from a container where it was pressurized or refrigerated, it may first escape and behave as a heavy gas and sink in the air (even if it has a Vapor Density value less than 1). Also, the Specific Gravity comparisons are for fresh water (density 1.0 g/mL). If your spill is in salt water (density about 1.027 g/mL), you need to adjust the point of comparison. There are some chemicals that will sink in fresh water and float in salt water.
Chemical Formula: |
|
Flash Point: data unavailable
Lower Explosive Limit (LEL): data unavailable
Upper Explosive Limit (UEL): data unavailable
Autoignition Temperature: data unavailable
Melting Point:
144°F Alpha form; 90.5°F Beta form; 62.2°F Gamma form
(EPA, 1998)
Vapor Pressure:
73 mmHg at 77°F Alpha form; 344 mmHg at 77°F Beta form; 433 mmHg at 77°F Gamma form
(EPA, 1998)
Vapor Density (Relative to Air):
2.76
(EPA, 1998)
- Heavier than air; will sink
Specific Gravity:
1.92
at 68°F
Gamma form (liquid)
(EPA, 1998)
- Denser than water; will sink
Boiling Point:
113°F
at 760 mmHg
all forms
(EPA, 1998)
Molecular Weight:
80.06
(EPA, 1998)
Water Solubility: data unavailable
Ionization Energy/Potential: data unavailable
IDLH: data unavailable
AEGLs (Acute Exposure Guideline Levels)
Exposure Period | AEGL-1 | AEGL-2 | AEGL-3 |
---|---|---|---|
10 minutes | 0.2 mg/m3 | 8.7 mg/m3 | 270 mg/m3 |
30 minutes | 0.2 mg/m3 | 8.7 mg/m3 | 200 mg/m3 |
60 minutes | 0.2 mg/m3 | 8.7 mg/m3 | 160 mg/m3 |
4 hours | 0.2 mg/m3 | 8.7 mg/m3 | 110 mg/m3 |
8 hours | 0.2 mg/m3 | 8.7 mg/m3 | 93 mg/m3 |
(NAC/NRC, 2024)
ERPGs (Emergency Response Planning Guidelines)
Chemical | ERPG-1 | ERPG-2 | ERPG-3 |
---|---|---|---|
Sulfuric Acid (Oleum [8014-95-7], Sulfur Trioxide [7446-11-9], and Sulfuric Acid [7664-93-9]) | 2 mg/m3 | 10 mg/m3 | 120 mg/m3 |
indicates that odor should be detectable near ERPG-1.
(AIHA, 2022)
PACs (Protective Action Criteria)
Chemical | PAC-1 | PAC-2 | PAC-3 |
---|---|---|---|
Sulfur trioxide (7446-11-9) | 0.2 mg/m3 | 8.7 mg/m3 | 160 mg/m3 |
(DOE, 2024)
The
Regulatory Information fields
include information from
the U.S. Environmental Protection Agency's Title III Consolidated List of
Lists,
the U.S. Cybersecurity and Infrastructure Security Agency's Chemical Facility
Anti-Terrorism Standards,
and the U.S. Occupational Safety and Health Administration's
Process Safety Management of Highly Hazardous Chemicals Standard List
(see more about these
data sources).
EPA Consolidated List of Lists
Regulatory Name | CAS Number/ 313 Category Code |
EPCRA 302 EHS TPQ |
EPCRA 304 EHS RQ |
CERCLA RQ | EPCRA 313 TRI |
RCRA Code |
CAA 112(r) RMP TQ |
---|---|---|---|---|---|---|---|
Sulfur trioxide | 7446-11-9 | 100 pounds | 100 pounds | 10000 pounds |
(EPA List of Lists, 2024)
CISA Chemical Facility Anti-Terrorism Standards (CFATS)
RELEASE | THEFT | SABOTAGE | ||||||||
---|---|---|---|---|---|---|---|---|---|---|
Chemical of Interest | CAS Number | Min Conc | STQ | Security Issue |
Min Conc | STQ | Security Issue |
Min Conc | STQ | Security Issue |
Sulfur trioxide | 7446-11-9 | 1.00 % | 10000 pounds | toxic |
(CISA, 2007)
OSHA Process Safety Management (PSM) Standard List
Chemical Name | CAS Number | Threshold Quantity (TQ) |
---|---|---|
Sulfur Trioxide (also called Sulfuric Anhydride) | 7446-11-9 | 1000 pounds |
Sulfuric Anhydride (also called Sulfur Trioxide) | 7446-11-9 | 1000 pounds |
(OSHA, 2019)
This section provides a listing of alternate names for this chemical,
including trade names and synonyms.
- SULFAN
- SULFUR OXIDE (SO3)
- SULFUR TRIOXIDE
- SULFUR TRIOXIDE, STABILIZED
- SULFUR TRIOXIDE, [STABILIZED]
- SULFURIC ANHYDRIDE
- SULFURIC OXIDE
- SULPHUR TRIOXIDE
- SULPHUR TRIOXIDE, STABILIZED
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