Potassium Hydroxide

Classification

Corrosive to metals, Category 1; Acute toxicity (oral), Category 4; Skin corrosion, Category 1A; Serious eye damage, Category 1

Hazard statements

• H290 May be corrosive to metals.
• H302 Harmful if swallowed.
• H314 Causes severe skin burns and eye damage.

Key precautionary statements

• P234 Keep only in original packaging.
• P260 Do not breathe dust or mist.
• P264 Wash hands thoroughly after handling.
• P280 Wear protective gloves, protective clothing, eye protection and face protection.
• P301+P330+P331+P310 IF SWALLOWED: Rinse mouth. Do NOT induce vomiting. Immediately call a POISON CENTER or doctor.
• P303+P361+P353 IF ON SKIN (or hair): Take off immediately all contaminated clothing. Rinse skin with water or shower.
• P305+P351+P338+P310 IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing. Immediately call a POISON CENTER or doctor.
• P405 Store locked up.

Federal OSHA has no PEL for potassium hydroxide. NIOSH and ACGIH both set 2 mg/m³ as a ceiling that should never be exceeded during the workday, and Cal/OSHA enforces the same 2 mg/m³ ceiling. NIOSH has not set an IDLH value. These are the same numbers used for its close relative sodium hydroxide. Airborne exposure comes from dust and from mists of caustic solutions; skin contact with the solid or strong solutions causes burns regardless of air levels. Even without a federal PEL, the OSHA Hazard Communication standard and the general duty clause still apply. State OSHA plans may set different limits.

• Appearance: Odorless white or slightly yellow lumps, rods, flakes, sticks or pellets. Commonly handled as a water solution.
• Odor: Odorless
• Molecular weight: 56.1
• Boiling point: 2415°F (1324°C)
• Melting point: 716°F (380°C)
• Flash point: Not applicable (noncombustible solid)
• Explosive limits: Not applicable
• Vapor pressure: 1 mmHg at 1317°F (negligible at room temperature)
• Specific gravity: 2.04
• Water solubility: 107% at 59°F; dissolving releases a lot of heat

Inhalation

Dust or mist irritates the nose, throat and lungs, causing coughing and sneezing. High exposure can cause fluid buildup in the lungs (pulmonary edema), a medical emergency.

Skin

Causes severe chemical burns. As with other strong alkalis, damage can progress before pain is felt, so rinse at once after any contact.

Eyes

Causes severe burns and can cause permanent eye damage, including blindness.

Ingestion

Harmful if swallowed. Burns the mouth, throat and stomach and can cause vomiting and diarrhea. Get medical attention immediately.

Target organs

Eyes, skin, respiratory system

Long-term effects

Repeated exposure may cause bronchitis. The New Jersey Department of Health notes that a skin allergy may develop. It has not been tested for cancer or reproductive effects.

Gloves

For solutions, the New Jersey Department of Health lists butyl, nitrile, neoprene, PVC, Viton and Barrier gloves. See hand protection and check the glove maker's data for your concentration.

Eyes and face

Chemical splash goggles, plus a face shield when handling solutions or large amounts of solid.

Respiratory

Not normally needed with good ventilation. NIOSH gives no respirator table for this substance. NJDOH advises a full-facepiece air-purifying respirator with particulate (N, R or P95) filters above 2 mg/m³ and a pressure-demand supplied-air respirator above 20 mg/m³. Any respirator use needs a written respiratory protection program.

Clothing

Chemical-resistant apron, sleeves and boots; NJDOH lists Tychem BR, Responder and TK suits. Remove clothing promptly if wet or contaminated, change daily, and keep an eyewash and quick drench shower nearby.

Store in tightly closed containers in a cool, dry, well-ventilated corrosives area away from water and combustibles. The solid absorbs moisture from the air, so keep containers sealed. It attacks some plastics, rubbers and coatings.

Avoid creating dust. When making solutions, add potassium hydroxide slowly to cold water while stirring, never water to the solid, because mixing releases enough heat to boil and spatter.

Keep away from

• Water and moisture (heat release; see water-reactive substances)
• Strong acids such as hydrochloric acid and sulfuric acid (violent reaction)
• Metals such as aluminum, zinc, tin and lead (release flammable hydrogen gas when wet)
• Halogenated hydrocarbons, maleic anhydride, nitro compounds and ammonium salts
• Reducing agents such as lithium, sodium, aluminum and their hydrides

• Evacuate the area and keep unprotected people away.
• Wear gloves, goggles, face shield and protective clothing; use respiratory protection for dust.
• For solid spills, collect the material without raising dust (use a vacuum, do not dry sweep) and place it in sealed containers.
• For solution spills, soak up with dry sand, earth or similar inert material and place in sealed containers.
• Keep out of drains, sewers and waterways.
• For larger incidents, refer to ERG Guide 154.

Suitable extinguishing media

• Use the agent best suited to the surrounding fire (potassium hydroxide does not burn)
• Water spray to cool fire-exposed containers, keeping water out of the containers

Special hazards

Noncombustible, but contact with water can release enough heat to ignite nearby wood, paper or oil. Reacts with wet aluminum, zinc and tin to release flammable hydrogen gas. Fires produce corrosive potassium oxides. Firefighters should wear SCBA and full protective gear.

• OSHA Hazard Communication (29 CFR 1910.1200): Hazardous chemical; labels, safety data sheets and worker training required.
• OSHA Air Contaminants (29 CFR 1910.1000): No PEL established.
• CERCLA hazardous substance (40 CFR 302.4; Clean Water Act list at 40 CFR 117.3): Reportable quantity 1,000 lb (454 kg).
• EPCRA Section 302 (40 CFR 355): Not listed as an extremely hazardous substance.
• EPCRA Section 313 / TRI (40 CFR 372.65): Not listed.
• DOT Hazardous Materials (49 CFR 172.101): UN1813 Potassium hydroxide, solid, Class 8, PG II. Solutions ship as UN1814.

• NIOSH Pocket Guide: Potassium hydroxide
• OSHA Occupational Chemical Database: Potassium hydroxide
• NJ Department of Health Hazardous Substance Fact Sheet: Potassium hydroxide
• Sigma-Aldrich SDS: Potassium hydroxide (product 221473)
• 40 CFR 117.3: Reportable quantities of hazardous substances