Pyrophoric and Water-Reactive Chemical Safety

Note: This page includes an overview of pyrophoric and water reactive safety. Please refer to the EHS Pyrophorics SOP for more detailed information before using pyrophoric materials (https://ehs.mit.edu/site/pyrophorics). 

Contents

Classification
Engineering Controls
Personal Protective Equipment
Waste Management Guidelines
Lab Specific Standard Operating Procedures
Identifying Pyrophoric and Water-Reactive Materials
Example Pyrophoric and Water-Reactive Materials

Classification

Pyrophoric substances are liquids, solids, or gases that will ignite spontaneously in air at or below 130 0F (54.4 0C). To receive the pyrophoric classification under GHS a chemical must ignite within 5 minutes in air. However, chemicals that ignite after 5 minutes also pose a significant risk to users and should be handled as pyrophoric.

Water-reactive substances are substances that react with water or moisture to release a gas that is either flammable or a health hazard. When water contacts a water-reactive substance, enough heat may be generated to cause spontaneous combustion or an explosion. The guidelines on this page refer to water-reactive substances that have a risk of igniting on contact with moisture, not those that only release toxic gases.

Engineering Controls

General guidance for handling pyrophoric and water-reactive chemicals is outlined below. However, many factors must be considered when determining what additional controls are required, including but not limited to the specific pyrophoric chemical(s) being used, type of application, and other hazards. For example, semiconductor research can involve pyrophoric materials that are also highly toxic, requiring additional controls. Contact your EHS coordinator or the EHS Office for more specific guidance on appropriate controls based on your lab’s research.

Depending on the materials and process, pyrophoric and water-reactive materials should be used in a chemical fume hood (over a spill tray) using techniques that prevent the material from contacting air or in an inert-atmosphere glove box according to the manufacturer's recommendations. 

Before using pyrophoric reagents refer to the Aldrich Technical Bulletins AL-164 and AL-134, which provide detailed instructions on using standard syringe and double-tipped needle transfer techniques to prevent contact with air. Some pyrophoric and water-reactive materials must be handled in a gas-tight syringe to prevent exposure to air. 

Personal Protective Equipment (PPE)

Flame resistant (FR) lab coats are required when handling pyrophoric substances, including chemicals that release flammable gases that may ignite spontaneously and self-heating chemicals that may catch fire outside of a glove box. FR lab coats should also be worn when working with chemicals that react violently with water or release flammable gas, or when performing potentially vigorous reactions.

Protective eyewear is required when handling pyrophoric and water-reactive materials. Fully enclosed safety goggles or a face shield are preferred, as they offer greater facial protection than safety glasses. 

Gloves are required when handling pyrophoric and water-reactive materials. It is recommended that Nomex gloves be worn between two pairs of nitrile gloves for fire protection purposes. 

Clothing made from polyester and other synthetic fabrics and loose clothing should not be worn. Always wear long pants and closed toe shoes within the lab. Loose or long hair should be tied back to prevent ignition in the event of a flash fire. 

Waste Management Guidelines

Excess pyrophoric chemicals should be treated as hazardous waste. Due to their properties special procedures may be required for waste collection and labs may incur disposal fees based on factors outlined below.

Contact EHS if several bottles are removed from storage at one time, as a fee may be applied depending on the volume. The more toxic and hazardous the chemical and the larger the bottle, the higher the cost tends to be.

Nonreturnable pyrophoric gas cylinders will also incur a cost at the time of disposal. Contact EHS for disposal rates and information on the removal process. 

Certain metal powders, such as fine aluminum powder, should be submerged in oil prior to waste collection from the lab. Debris with aluminum powder may be collected with a thin coating of oil and kept separate from other debris waste streams.

Reactive metals, such as lithium, potassium and magnesium, should also be submerged under oil and handled as hazardous waste. Contact EHS for additional guidance.  

Additional EHS resources:
•    Reactive Waste - https://ehs.mit.edu/site/waste-management/hazardous-waste-management/rea...
•    Non-returnable Cylinder Disposal - https://ehs.mit.edu/site/alternatives-non-returnable-gas-cylinders

Lab Specific Standard Operating Procedures (SOPs)

A laboratory specific SOP is required for use of pyrophoric materials. Contact your DLC’s EHS Coordinator or the EHS Office for assistance.

Identifying Pyrophoric and Water-Reactive Materials

Each researcher is responsible for determining if the chemicals used are pyrophoric or water-reactive. To determine if a flammable solid, liquid, or gas is pyrophoric or could ignite on contact with moisture, do the following:

A number of reference sources are available to help with determining if a chemical is pyrophoric or water-reactive:
1)    SDS for the chemical from the manufacturer
2)    Pubchem (https://pubchem.ncbi.nlm.nih.gov)
3)    Cameochemicals (https://cameochemicals.noaa.gov)
4)    The EHS Office (environment@mit.edu)

Example Pyrophoric and Water-Reactive Materials

Note that this list includes examples of pyrophoric and water-reactive materials but is not comprehensive. 

If a flammable chemical is not on this list the user is responsible for determining whether the chemical should be handled as pyrophoric.  Contact the EHS Office for assistance if there is any uncertainty (environment@mit.edu). 

Downloadable PDF with hazard details

Metal Hydrides such as:
Aluminum Borohydride (CAS 16962-07-5)
Calcium Hydride (CAS 7789-78-8)
Diisobutylaluminum Hydride (CAS 1191-15-7)
Lithium Aluminum Hydride (CAS 16853-85-3)
Lithium Borohydride (CAS 16949-15-8)
Lithium Hydride (CAS 7580-67-8)
Potassium Hydride (CAS 7693-26-7)
Sodium Borohydride    (CAS 16940-66-2)
Sodium Hydride (CAS 7646-69-7)
Super-Hydride (Lithium Triethylborohydride) (CAS 22560-16-3)
Sodium Triacetoxyborohydride (CAS 56553-60-7)
Sodium Triethylborohydride (CAS 17979-81-6)

Non-Metal Hydrides such as: 
9-Borabicyclo [3.3.1]Nonane (CAS 280-64-8)
Arsine (CAS 7784-42-1) 
Borane Tetrahydrofuran Complex (CAS 14044-65-6)
Borane Trifluoride  (CAS 7637-07-2)
Di-T-Butylmethylphosphine (CAS 6002-40-0)
Di-Tert-Butylphosphine (CAS 819-19-2)
Diborane (CAS 19287-45-7)
Dichloroborane (CAS 13701-67-2)
Dichloroisopropylphosphine (CAS 25235-15-8)
Dichlorosilane (CAS 4109-96-0)
Diphenylphosphine (CAS 829-85-6)
Disilane (CAS 1590-87-0)
Methyl Silane (CAS 992-94-9)  
Phosphine (CAS 7803-51-2)
Polyboranes    
Silane (CAS 7803-62-5)
Tetrabutylammonium Borohydride (CAS 33725-74-5)
Tetrafluoroboric Acid-Diethyl Ether Complex (CAS 67969-82-8)
Tetramethylammonium Triacetoxyborohydride (CAS 109704-53-2)
Tri-N-Butylphosphine (CAS 998-40-3)
Tri-Tert-Butylphosphine (CAS 13716-12-6)
Tributylborane (CAS 122-56-5)
Tributylphosphine (CAS 998-40-3)
Trichlorosilane (CAS 10025-78-2)
Triethyl Phosphone (CAS 554-70-1)
Triethylborane (CAS 97-94-9)

Metal Halides such as:
Titanium (II) Chloride (10049-06-6)

Alkali Metals such as:
Lithium (CAS 7439-93-2)
Potassium (CAS 7440-09-7)
Sodium (CAS 7440-23-5

Metal Carbonyls such as:
Cobalt Carbonyl (CAS 10210-68-1)
Cyclopentadienyl Iron Dicarbonyl Dimer (CAS 12154-95-9)
Disodium Tetracarbonyl Ferrate Dioxane Complex (CAS 59733-73-2)
Iron Carbonyl (CAS 13463-40-6)  
Nickel Carbonyl (CAS 13463-39-3)

Metal Powders* such as:          
Aluminum (CAS 7429-90-5)
Barium (CAS 7440-39-3)
Cadmium (CAS 7440-43-9)
Calcium (CAS 7440-70-2)
Cerium (CAS 7440-45-1)
Cesium (CAS 7440-46-2)
Chromium (CAS 7440-47-3)
Cobalt (CAS 7440-48-4)
Europium (CAS 7440-53-1)
Hafnium (CAS 7440-58-6)
Iridium (CAS 7439-88-5)
Iron  H251 (CAS 7439-89-6)
Lead (CAS 7439-92-1)
Magnesium (CAS 7439-95-4)
Manganese (CAS 7439-96-5)
Nickel (CAS 7440-02-0)
Palladium (CAS 7440-05-3)
Platinum (CAS 7440-06-4)
Plutonium (CAS 7440-07-5)
Rhodium (CAS 7440-16-6)
Rubidium (CAS 7440-17-7)
Strontium (CAS 7440-24-6)
Tantalum (CAS 7440-25-7)
Technetium  (CAS 7440-26-8)
Thorium (CAS 7440-29-1)
Titanium   (CAS 7440-32-6)
Uranium (CAS 7440-61-1)
Vanadium (CAS 7440-62-2)
Zinc (CAS 7440-66-6)
Zirconium (CAS 7440-67-7)

*NOTE: Many metal powders present special storage and handling concerns when finely divided, including hazards such as air- or water-reactivity or explosive dust generation. Whether a given metal powder exhibits these properties depends on multiple factors, including but not limited to particle size, surface area, moisture level, purity, etc.

Please contact your EHS Coordinator or the  EHS Office for assistance when working with small-particle-size metal powders.