Flammables

Flammable chemicals are of particular concern because improper handling can cause a fire, which can spread quickly out of control. The purpose of this section is to present the safe handling and storage guidelines for all flammable materials used in the lab.

1. Key Terms
2. Identification of Flammables
3. Classification of Liquids
4. // OTHER //

Key Terms

Identification of Explosive or Shock-Sensitive Materials

Toxic chemicals are easily identified by the "Skull and Crossbones" pictogram under the globally harmonized system (GHS) of hazard communication. The symbol is easily recognized as a skull and crossbones.

The older-style toxic hazard symbol, which has now been phased-out, also depicts a skull and crossbones, but is instead contained within a bright orange square. Any in-house / custom labels should be replaced with new GHS-compliant labels.

The U.S. Department of Transportation (DOT) placard is used to label shipments of toxins during shipping.

Classification of Liquids

1. Class IA: Flash Point less than 73°F (22.8°C); Boiling Point less than 100°F (37.8°C)
2. Class IB: Flash Point less than 73°F (22.8°C); Boiling Point equal to or greater than 100°F (37.8°C)
3. Class IC: Flash Point equal to or greater than 73°F  (22.8°C), but less than 100°F (37.8°C)
4. Class II: Flash Point equal to or greater than 100°F  (37.8°C), but less than 140°F (60°C)
5. Class IIIA: Flash Point equal to or greater than 140°F  (60°C), but less than 200°F (93.3°C)
6. Class IIIB: Flash Point equal to or greater than 200°F  (93.3°C)

Classification of flammable and combustible liquids are addressed in Chapter 4, Section 3.1 and 3.2 of NFPA 45 (2015). Access to the NFPA is free online with registration.

Flash Point and NFPA Classes for Common Solvents

Storage Containers

Only approved containers and metal portable tanks authorized by National Fire Protection Association policy NFPA-45 shall be used to store flammable liquids. Storage container requirements are addressed in Chapter 9 and summarized in Table 9.1.2 of NFPA 45 (2015).

* Class IA and IB liquids may be stored up to one gallon in glass containers if liquid purity would be affected by storage in metal containers or if the metal containers could undergo excessive corrosion by the contained liquid.

Laboratory Unit Hazard Classification

Laboratories may be classified based on the amount of flammable or combustible liquids within the unit as either Class A¹ (high fire hazard), Class B² (moderate fire hazard), Class C³ (low fire hazard), or Class D (minimal fire hazard), as listed in the table below.  These values are based on summarized in Table 9.1.1 of NFPA 45 (2015).

¹ Laboratories listed as Class A shall be considered high hazard laboratories and should not be used as instructional laboratories.
² Laboratories listed as Class B shall be considered intermediate hazard laboratories. If a Class B laboratory is used for instructional purposes, the quantities of allowable flammable and combustible liquids should be 50% of those listed in the above table.
³ Laboratories listed as Class C shall be considered low hazard laboratories. If a Class C laboratory is used for instructional purposes, the quantities of allowable flammable and combustible liquids should be 50% of those listed in the above table.

Only NFPA 45 approved amounts of flammable liquids shall be stored in laboratory units outside of flammable liquid storage rooms. The volumes listed here are for quantities stored in approved storage cabinets and safety cans. Allowable quantities stored outside of approved storage cabinets and safety cans (e.g., on benchtops and in non-flammable storage cabinets) are 50% of the quantities listed below.

Refrigerator Storage of Flammables

Domestic Refrigerator/Freezers

Domestic household refrigerators have internal components located inside the inner compartment such a s thermostats, lights, and switches that can create a spark capable of igniting vapors from flammable liquids stored inside. This type of refrigerator is the lowest cost so many labs use this type of refrigerator for storing non-flammable chemicals. Domestic Refrigerators must be labeled properly. Flammable materials must never be stored in this type of refrigerator.

Modified Domestic Refrigerator/Freezers

Some laboratories have existing modified domestic household refrigerators that have had the internal components re-located outside the inner compartment by qualified electricians to make them safe for storage of flammable materials. The National Fire Protection Association (NFPA 45) Standard on Fire Protection for Laboratories Using Chemicals, describes the modification procedure and the proper notices to be used. This practice is not recommended. UCD FIRENET: Flammable Liquid Storage Page 6 of 6 6/13 Extreme caution should be exercised because in some cases not all the possible sources of ignition may have been isolated. Using previously modified refrigerators is acceptable if the laboratory inspects them regularly for defects such as frayed wiring. Defective refrigerators should not be used to store flammable materials.

Laboratory-Safe or Flammable Material Refrigerator/Freezers

Laboratory-safe refrigerators are designed to prevent ignition of flammable vapors or gases that may be present inside the refrigerator only. Laboratory-safe or flammable material refrigerator/freezers should be purchased whenever a refrigerator is needed to store flammable liquid. These refrigerator/freezers are designed to prevent ignition of flammable vapors inside the storage compartment. All the electrical components in this type of refrigerator are located outside the refrigerator, and the compressor is sealed or located at the top of the unit. Flammable material refrigerators also may incorporate design features such as thresholds, selfclosing doors, magnetic door gaskets, and special inner shell materials that control or limit the damage should a reaction occur within the storage compartment. The refrigerators must be U.L. Listed as Flammable Material Storage Refrigerators. Ultra low freezers (less than -40°F) generally cannot be approved for storage of flammable materials.

Explosion Proof Refrigerator/Freezers

Explosion-proof refrigerators are designed to prevent ignition of flammable vapors or gases that may be present inside and outside the refrigerator. This type of refrigerator is used in locations such as solvent dispensing rooms, where a flammable atmosphere may develop at some time in the room. Explosion-proof refrigerators have very limited use and require special hazardous-location wiring rather than the simple plug-in type power cord. Consult with the UC Davis Fire Prevention Office before purchasing an Explosion Proof Refrigerator.