Flammable Safety Cabinets vs. Outdoor Chemical Storage Lockers – What is the Difference?

Working with flammable, and combustible or corrosive liquids can be confusing and dangerous. To ensure a safe workplace, there are many regulations that apply to their storage, handling and dispensing.

Besides the obvious safety risks, fires and explosions can also cause property damage, financial losses and environmental incidents. Failure to follow regulations may result in large penalties and fines. Prevent these ramifications by storing chemicals in approved chemical storage cabinets or lockers.

Regulations for Chemical Storage

Chemical storage regulations are based on how dangerous the chemical is. The NFPA and OSHA classify chemicals by their physical and chemical properties. The more flammable a chemical is, the greater the restrictions on its use and storage.

Summary tables of the two classification systems are as follows:

Boiling Point
Class: I-A Flashpoint: < 73.4 F (23 C) Boiling Point: >= 100 F (38 C)
Class: I-B Flashpoint: < 73.4 F (23 C) Boiling Point: <= 100 F (38 C)
Class: I-C Flashpoint: 73.4-100 F (23-38 C) Boiling Point:  
Class: II Flashpoint: 101-140 F (39-60 C) Boiling Point:  
Class: III-A Flashpoint: 141-199 F (61-93 C) Boiling Point:  
Class: III-B Flashpoint: >200 F (>93 C) Boiling Point:  

Table 1 - NFPA Flammable Classifications

Category Flashpoint Boiling Point
Category: 1 Flashpoint: < 73.4 F (23 C) Flashpoint: <= 95 F (35 C)
Category: 2 Flashpoint: < 73.4 F (23 C) Boiling Point: > 95 F (35 C)
Category: 3 Flashpoint: 73.4-140 F (23-60 C) Boiling Point:  
Category: 4 Flashpoint: 140-199.4 F (60-93 C) Boiling Point:  

Table 2 - OSHA Flammable Categories

Small Volumes Don’t Need Special Storage

The volume of chemicals in storage matters. Small volumes of flammable liquids may be stored outside flammable safety cabinets or chemical storage lockers. Per OSHA 1910.106(e)(2)(ii)[b], these liquids must be in containers and contain no more than:

  • 25 gallons of Category 1
  • 120 gallons of Category 2, 3 or 4
  • 660 gallons of Category 2, 3 or 4 in a single portable tank

Flammable Safety Cabinets

Flammable chemical safety cabinets are designed specifically for safely storing chemicals indoors. They provide heat resistance to protect from devastating fires. They are often located near point-of-use, which is convenient for workers. Most cabinets hold enough supplies for daily use. But, there are volume limits depending on the flammable classification of the materials stored.

Justrite Sure-Grip EX Safety Cabinets have air gaps between inner and outer walls for fire resistance. Self-latching doors provide maximum protection under fire conditions. Justrite also supplies safety cabinets for combustibles, hazardous materials and corrosives.

Maximum allowable quantities (MAQs) of chemicals that can be stored in safety cabinets per control areas are as follows (OSHA 1910.106 (d)(3)(i)):

  • 60 gallons of Class I and II (Category 1, 2 and 3)
  • 120 gallons of Class III (Category IV)

Regulators allow the use of more than one safety cabinet to extend these storage volumes. There is a limit of three safety cabinets per internal storage area. But, MAQs sometimes differ per local fire codes and laws. Always consult the authority having jurisdiction (AHJ) for final determination.

Outdoor Chemical Storage Lockers

When storing drums or bulk quantities of flammable, combustible and corrosive chemicals, flammable safety cabinets may not provide the necessary capacity. But the costs of building another storage room may not be feasible. Designed as separate, detached structures for outdoor use, Justrite outdoor storage lockers provide a suitable solution for the storage of Class I, II, and III flammable/combustible liquids, hazardous materials and wastes. Lockers come in standard sizes from 2- to 16-drum capacities. Custom-sized units are available on request.

Justrite prefabricated outdoor storage lockers are constructed from sturdy, heavy gauge steel, with fire resistant gypsum board encased between external and internal sheeting. Gravity air-flow vents remove flammable vapors from the locker. Leakproof secondary containment sumps prevent environmental contamination. Available optional accessories include loading ramps, shelving and fire suppression systems. Lockers are FM-approved and meet EPA and NFPA requirements.Most chemical storage lockers stand away from occupied buildings. The distance depends on the chemicals being stored and the locker’s fire rating. According to IBC, for hazard occupancy of H2 or less, fire ratings and location distances for chemical storage lockers are as follows:

Contact Justrite for Compliant Flammable Safety Cabinets and Outdoor Chemical Storage Lockers

At Justrite, we manufacture both flammable safety cabinets and outdoor chemical storage lockers. We also have access to the U.S. Chemical Storage range of customized chemical storage buildings. As experts in chemical storage, we’ll work with you directly to help assess your needs and recommend the best solution to keep your workplace safe. Learn more about Justrite here.


Posted in Storage and Safety