Pyrophoric Materials

Definition and Hazards

Pyrophoric materials are substances that ignite instantly upon exposure to oxygen. They can also be water-reactive, where heat and hydrogen (a flammable gas) are produced. Other common hazards include corrosivity, teratogenicity and organic peroxide formation, along with damage to the liver, kidneys and central nervous system. Examples of such materials include metal hydrides, finely divided metal powders, nonmetal hydride and alkyl compounds, white phosphorus, alloy of reactive materials and organometallic compounds, including alkyllithiums.

Failure to follow proper handling techniques could result in serious injury or death.

Controlling the Hazards

If possible, use safer chemical alternatives.
Limit the amount purchased and do not accumulate unneeded pyrophoric reagents.
BEFORE working with pyrophoric reagents, read the relevant Material Safety Data Sheets (MSDS) and associated technical bulletins. The MSDS must be reviewed before using an unfamiliar chemical and periodically as a reminder.
A Standard Operating Procedure and Hazard Assessment should be prepared for each process involving pyrophoric or water-reactive materials.
On-the-job training should be completed and documented.
Conduct an emergency drill reviewing the procedures to be taken in an emergency.
Review the location of the safety shower, eyewash, telephone (dial 911) and fire extinguisher.

Personal Protective Equipment

ALWAYS wear the proper PPE at all times when handling pyrophoric materials.

Eye Protection:

Chemical splash goggles or safety glasses must be worn whenever handling pyrophoric chemicals. Ordinary prescription glasses will NOT provide adequate protection.
A face shield is required any time there is a risk of explosion, large splash hazard or a highly exothermic reaction. Portable shields are also acceptable.

Skin Protection:

Gloves must be worn when handling pyrophoric chemicals. Nitrile gloves should be adequate for handling most of these in general laboratory settings but they are combustible. Be sure to use adequate protection to prevent skin exposures. Sigma-Aldrich recommends the use of nitrile gloves underneath neoprene gloves.
Avoid wearing synthetic clothing while working with pyrophorics. A lab coat or apron (not made from easily ignited material like nylon or polyester) must be worn. Special fire-resistant lab coats made from Nomex are more expensive, but recommended for labs using these reagents routinely.
No open toe shoes are allowed.

Designated Areas

Fume Hood:

Many pyrophoric chemicals release noxious or flammable gases and should be handled in a laboratory hood with the sash down at the lowest feasible position. In addition, some pyrophoric materials are stored under kerosene (or other flammable solvent); therefore the use of a fume hood (or glove box) is required to prevent the release of flammable vapors into the laboratory.

Glove (dry) box:

Glove boxes are an excellent device to control pyrophoric chemicals when inert or dry atmospheres are required. When using a disposable plastic syringe, glove boxes are also recommended.

Important Steps to Follow

A “dry-run” of the experiment should be performed using low-hazard materials, such as water or solvent, as appropriate.
If possible, use the “buddy system.” Working alone with pyrophorics is strongly discouraged.
Conduct the procedure only after a supervisor has observed the user performing the proper technique unassisted.
All glassware used for pyrophorics should be oven-dried and free of moisture.
Keep an appropriate fire extinguisher or extinguishing material close at hand.
Remove all other flammable material from the hood, as well as any clutter.
Secure the pyrophoric reagent bottle to a stand.
Sigma Aldrich recommends the use of a long needle, 1-2 foot, and a syringe that is twice the volume of liquid to be transferred.
Secure the syringe so if the plunger blows out of the body it, and the contents will not splash anyone.
Avoid the transfer of large volumes (>20 mL) using a syringe. The cannula technique is recommended.

Further details, such as safe experiment set up diagrams, can be found in the references listed below.

Storage

Pyrophoric chemicals should be stored under an atmosphere of inert gas or under kerosene as appropriate. Avoid areas with heat/flames, oxidizers and water sources. Containers carrying pyrophoric materials must be clearly labeled with the correct chemical name and hazard warning. Do NOT allow pyrophoric chemicals stored in solvent to dry out. Check periodically to ensure there is a visible amount of solvent in the bottle.

Disposal

All materials that contain or are contaminated with pyrophoric chemicals should be disposed of as hazardous waste. Submit a Hazardous Materials Pick-up Request.
Proper and complete hazardous waste labeling of containers is vital.
A container with residual material must NEVER be opened to the atmosphere.
If the pyrophoric chemical was originally stored in solvent and is dried, please hydrate the chemical with an appropriate solvent before pick-up. The best solvent to use is the same solvent used for the solution of the original reagent.

Emergency Procedures

Keep material within arm’s length to absorb spills. Powdered lime, dry sand, Celite^® (diatomaceous earth) or clay based kitty litter should be used to completely smother and cover any spill that occurs.
If a person is exposed, or on fire, the use of the stop, drop, and roll method, safety shower, a fire blanket or fire extinguisher are the most effective means of controlling clothing on fire. If a safety shower is available, keep the person under the shower for at least 15-20 minutes to ensure all chemicals are washed away.
The recommended fire extinguisher is a standard dry powder (ABC) type. Class D extinguishers are recommended for combustible solid metal fires (such as sodium), but not for organolithium reagents.
Call 911 for emergency assistance