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CAS Registry No.: 7783-06-4
Other Names: H2S, hydrogen sulphide, sour gas
Main Uses: Manufacture of other chemicals; manufacturing processes; environmental contaminant; by-product of industrial processes.
Appearance: Colourless gas.
Odour: Rotten eggs. Sickening sweet odour at high concentrations. Can dull the sense of smell.
Canadian TDG: UN1053
A - Compressed Gas; B1 - Flammable Gas; D1A - Very Toxic; D2B - Toxic (Eye irritant)
Emergency Overview: Colourless gas. Rotten eggs odour. COMPRESSED GAS. Contains gas under pressure. May explode if heated. EXTREMELY FLAMMABLE GAS. Distant ignition and flashback are possible. CONFINED SPACE HAZARD. Can accumulate in hazardous amounts in low-lying areas especially inside confined spaces. VERY TOXIC. Fatal if inhaled. May cause respiratory irritation. IRRITANT. Causes moderate or severe eye irritation. May cause frostbite.
Main Routes of Exposure: Inhalation; eye contact.
International Agency for Research on Cancer (IARC): Not specifically evaluated.
American Conference for Governmental Industrial Hygienists (ACGIH): Not specifically designated.
Inhalation: Take precautions to prevent a fire (e.g. remove sources of ignition). Take precautions to ensure your own safety before attempting rescue (e.g. wear appropriate protective equipment). Move victim to fresh air. Keep at rest in a position comfortable for breathing. If breathing is difficult, trained personnel should administer emergency oxygen. DO NOT allow victim to move about unnecessarily. Symptoms of pulmonary edema may be delayed. If breathing has stopped, trained personnel should begin artificial respiration (AR). If the heart has stopped, trained personnel should start cardiopulmonary resuscitation (CPR) or automated external defibrillation (AED). Avoid mouth-to-mouth contact by using mouth guards or shields. Immediately call a Poison Centre or doctor. Treatment is urgently required. Transport to a hospital. NOTE: Victims may pose a threat to responders due to the release of hydrogen sulfide from their clothing, skin, and exhaled air.
Skin Contact: Liquefied gas: quickly remove victim from source of contamination. DO NOT attempt to rewarm the affected area on site. DO NOT rub area or apply direct heat. Gently remove clothing or jewelry that may restrict circulation. Carefully cut around clothing that sticks to the skin and remove the rest of the garment. Loosely cover the affected area with a sterile dressing. DO NOT allow victim to drink alcohol or smoke. Immediately call a Poison Centre or doctor. Treatment is urgently required. Transport to a hospital. Double bag, seal, label and leave contaminated clothing, shoes and leather goods at the scene for safe disposal.
Eye Contact: Gas: immediately flush the contaminated eye(s) with lukewarm, gently flowing water for 15-20 minutes, while holding the eyelid(s) open. Liquefied gas: immediately and briefly flush with lukewarm, gently flowing water. DO NOT attempt to rewarm. Cover both eyes with a sterile dressing. DO NOT allow victim to drink alcohol or smoke. Immediately call a Poison Centre or doctor. Treatment is urgently required. Transport to a hospital.
Ingestion: Not applicable (gas).
First Aid Comments: Some of the first aid procedures recommended here require advanced first aid training. All first aid procedures should be periodically reviewed by a doctor familiar with the chemical and its conditions of use in the workplace.
Flammable Properties: EXTREMELY FLAMMABLE GAS. Can easily ignite. Can readily form explosive mixture with air at room temperature.
Suitable Extinguishing Media: Carbon dioxide, dry chemical powder, water spray or fog.
Specific Hazards Arising from the Chemical: Gas may travel a considerable distance to a source of ignition and flash back to a leak or open container. Gas may accumulate in hazardous amounts in low-lying areas especially inside confined spaces, resulting in a health hazard. Heat from fire can cause a rapid build-up of pressure inside cylinders. Explosive rupture and a sudden release of large amounts of gas may result. Cylinder may rocket. In a fire, the following hazardous materials may be generated: corrosive sulfur oxides.
Personal Precautions: Evacuate the area immediately. Isolate the hazard area. Keep out unnecessary and unprotected personnel. Evacuate downwind locations. Do not touch damaged containers or spilled product unless wearing appropriate protective equipment. Ventilate area. Eliminate all ignition sources. Use grounded, explosion-proof equipment. Distant ignition and flashback are possible.
Methods for Containment and Clean-up: Liquid: stop or reduce leak if safe to do so. If not, allow liquid to vapourize. Ventilate the area to prevent the gas from accumulating, especially in confined spaces. Gas: stop or reduce leak if safe to do so. Ventilate the area to prevent the gas from accumulating, especially in confined spaces.
Handling: Before handling, it is important that all engineering controls are operating and that protective equipment requirements and personal hygiene measures are being followed. Only trained personnel should work with this product. Do NOT work alone with this product. In event of a spill or leak, immediately put on escape-type respirator and exit the area. Use non-sparking ventilation systems, approved explosion-proof equipment and intrinsically safe electrical systems. Electrically bond and ground equipment. Ground clips must contact bare metal. Eliminate heat and ignition sources such as sparks, open flames, hot surfaces and static discharge. Post "No Smoking" signs. Prevent accidental contact with incompatible chemicals. Use the pressure regulator appropriate for cylinder pressure and contents. Secure cylinder in an up-right position. Protect cylinders from damage. Use a suitable hand truck to move cylinders; do not drag, roll, slide, or drop.
Storage: Store in an area that is: cool, dry, temperature-controlled, well-ventilated, out of direct sunlight and away from heat and ignition sources, separate from incompatible materials, an approved, fire-resistant area, clear of combustible and flammable materials (e.g. old rags, cardboard), on the ground floor or preferably, in an isolated, detached building. Electrically bond and ground containers. Ground clips must contact bare metal. Avoid bulk storage indoors. Empty containers may contain hazardous residue. Store separately. Keep closed.
ACGIH® TLV® - TWA: 1 ppm
ACGIH® TLV® - STEL [C]: 5 ppm
Exposure Guideline Comments: TLV® = Threshold Limit Value. TWA = Time-Weighted Average. STEL = Short-term Exposure Limit. C = Ceiling limit.
NOTE: In many (but not all) Canadian jurisdictions, the exposure limits are similar to the ACGIH® TLVs®. Since legislation varies by jurisdiction, contact your local jurisdiction for exact details. A list is available in the OSH Answers on Canadian Governmental Occupational Health & Safety Departments.
A list of which acts and regulations that cover exposure limits to chemical and biological agents is available on our website. Please note that while you can see the list of legislation for free, you will need a subscription to view the actual documentation.
Engineering Controls: Use a local exhaust ventilation and enclosure, if necessary, to control amount in the air. It may be necessary to use stringent control measures such as process enclosure to prevent product release into the workplace. Use non-sparking ventilation systems, approved explosion-proof equipment and intrinsically safe electrical systems in areas where this product is used and stored. Use a ventilation system separate from other exhaust ventilation systems. Filter the contaminated air before it is directly exhausted to the outside. Use leak and fire detection equipment and an automatic fire suppression system.
Eye/Face Protection: Wear chemical safety goggles. A face shield (with safety goggles) may also be necessary.
Skin Protection: Wear chemical protective clothing e.g. gloves, aprons, boots. In some operations: wear a chemical protective, full-body encapsulating suit and self-contained breathing apparatus (SCBA). Suitable materials include: Tychem® BR/LV, Tychem® Responder® CSM.
Up to 100 ppm:
(APF = 10) Any supplied-air respirator*.
(APF = 25) Any powered, air-purifying respirator with cartridge(s) providing protection against hydrogen sulfide.
(APF = 50) Any air-purifying, full-facepiece respirator (gas mask) with a chin-style, front- or back-mounted canister providing protection against hydrogen sulfide or Any self-contained breathing apparatus with a full facepiece.
*Reported to cause eye irritation or damage; may require eye protection.
APF = Assigned Protection Factor
Recommendations apply only to National Institute for Occupational Safety and Health (NIOSH) approved respirators. Refer to the NIOSH Pocket Guide to Chemical Hazards for more information.