Chlorine

Classification

Oxidizing gas, Category 1; Gas under pressure (liquefied gas); Acute toxicity (inhalation), Category 3; Skin irritation, Category 2; Serious eye irritation, Category 2; Specific target organ toxicity, single exposure, Category 3 (respiratory irritation); Hazardous to the aquatic environment (acute), Category 1

Hazard statements

• H270 May cause or intensify fire; oxidizer.
• H280 Contains gas under pressure; may explode if heated.
• H315 Causes skin irritation.
• H319 Causes serious eye irritation.
• H331 Toxic if inhaled.
• H335 May cause respiratory irritation.
• H400 Very toxic to aquatic life.

Key precautionary statements

• P220 Keep away from clothing and other combustible materials.
• P244 Keep valves and fittings free from oil and grease.
• P261 Avoid breathing gas.
• P271 Use only outdoors or in a well-ventilated area.
• P280 Wear protective gloves, protective clothing, eye protection and face protection.
• P304+P340 IF INHALED: Remove person to fresh air and keep comfortable for breathing.
• P370+P376 In case of fire: Stop leak if safe to do so.
• P403+P233 Store in a well-ventilated place. Keep container tightly closed.

The federal OSHA PEL for general industry is a 1 ppm ceiling that must never be exceeded; in construction and maritime the 1 ppm value applies as an 8-hour TWA. NIOSH recommends a 0.5 ppm ceiling over any 15 minutes. Cal/OSHA is stricter at 0.5 ppm TWA and 1 ppm STEL. Published ACGIH TLV values for chlorine vary between sources, so check the current ACGIH TLV book. No skin notation is assigned. State OSHA plans may set different limits.

• Appearance: Greenish-yellow gas, shipped as a liquefied compressed gas
• Odor: Pungent, irritating
• Molecular weight: 70.9
• Boiling point: -29°F (-34°C)
• Freezing point: -150°F (-101°C)
• Flash point: Not flammable, but a strong oxidizer that supports combustion
• Explosive limits: Not applicable
• Vapor pressure: 6.8 atm
• Relative gas density: 2.47 (heavier than air; collects in low areas)
• Water solubility: 0.7%

Inhalation

Irritates the eyes, nose and throat and causes coughing, choking, chest pain, headache, nausea and vomiting. Higher exposures cause fluid in the lungs (pulmonary edema) and pneumonitis, which can be delayed and can be fatal.

Skin

Irritates the skin and can cause dermatitis. Contact with the liquid causes frostbite.

Eyes

Causes serious eye irritation and tearing. Liquid contact causes frostbite.

Ingestion

Not a likely route for a gas.

Target organs

Eyes, skin, respiratory system

Gloves

Chemical-resistant gloves selected using the manufacturer's permeation data. Use insulated gloves where contact with liquid chlorine is possible.

Eyes and face

Chemical splash goggles and a face shield. Use a full-facepiece respirator where chlorine irritates the eyes.

Respiratory

Up to 5 ppm, a NIOSH-approved chemical cartridge respirator for chlorine. Up to 10 ppm, a full-facepiece cartridge respirator or gas mask with chlorine canister. Above 10 ppm (IDLH), unknown concentrations or emergencies, a pressure-demand self-contained breathing apparatus with full facepiece. Carry an escape respirator when handling chlorine.

Clothing

Protective clothing chosen for the task. Leak response may require a gas-tight encapsulating suit with self-contained breathing apparatus.

Store cylinders and containers upright and secured, with valve covers in place, in a cool, dry, well-ventilated area away from heat, moisture, combustible materials, oil and grease. Keep cylinder temperature below 125°F (52°C).

Only trained workers should connect or change containers. Keep valves and fittings free of oil and grease, check for leaks before use, and keep escape respirators and emergency equipment close by.

Keep away from

• Acetylene
• Ether
• Turpentine
• Ammonia
• Fuel gas
• Hydrogen
• Finely divided metals

• Evacuate and isolate the area. Stay upwind and out of low areas, where chlorine collects.
• Only trained responders with self-contained breathing apparatus and protective suits should approach the leak.
• Stop the leak if it can be done safely. Turn a leaking container so that gas, not liquid, escapes.
• Do not spray water on the leak or on liquid chlorine, which makes the leak worse. Water spray may be used to knock down vapors.
• Keep chlorine out of sewers, basements and confined spaces.
• Follow ERG Guide 124.

Suitable extinguishing media

• Chlorine does not burn. Use media suited to the surrounding fire
• Water spray to cool containers, applied without spraying the leak itself

Special hazards

Chlorine is a strong oxidizer that supports and intensifies fire and can react explosively with many fuels and finely divided metals. Containers can burst when heated, and steel can burn in chlorine at high temperatures. Firefighters need positive-pressure self-contained breathing apparatus. Keep contaminated runoff out of waterways.

• OSHA Hazard Communication (29 CFR 1910.1200): Hazardous chemical. Labels and safety data sheets are required.
• OSHA Air Contaminants (29 CFR 1910.1000, Table Z-1): PEL 1 ppm (3 mg/m³) ceiling.
• OSHA Process Safety Management (29 CFR 1910.119, Appendix A): Threshold quantity 1,500 lb.
• CERCLA (40 CFR 302.4): Hazardous substance, reportable quantity 10 lb.
• EPCRA Section 302 (40 CFR 355): Extremely hazardous substance, threshold planning quantity 100 lb, reportable quantity 10 lb.
• EPCRA Section 313 (TRI) (40 CFR 372.65): Listed.
• Clean Air Act 112(r) Risk Management Program (40 CFR 68.130): Threshold quantity 2,500 lb.
• DOT (49 CFR 172.101): UN1017, Chlorine, Division 2.3 with subsidiary hazards 5.1 and 8; Inhalation Hazard Zone B.

• NIOSH Pocket Guide: Chlorine
• OSHA Occupational Chemical Database: Chlorine
• PubChem: Chlorine GHS classification
• eCFR: EPCRA extremely hazardous substances, 40 CFR 355 Appendix A
• Westlake SDS: Chlorine