29 CFR 1910.106: OSHA Flammable Liquids

Regulatory citation: 29 CFR 1910.106, Flammable Liquids (Hazardous Materials, Subpart H)

What Is the OSHA Flammable Liquids Standard?

Section 1910.106 covers the storage, handling and use of flammable liquids in general industry. It sets rules for tank storage, piping, containers and portable tanks, industrial plants, bulk plants and other specialized facilities. For most workplaces, the key parts are paragraph (d) on containers and portable tanks and paragraph (e) on industrial plants.

A flammable liquid is any liquid with a flashpoint at or below 199.4 °F (93 °C). Liquids are divided into four categories that match the Hazard Communication Standard, so the category on a safety data sheet tells you which storage rules apply.

Why Flammable Liquid Controls Matter

Vapors from flammable liquids can travel to an ignition source and flash back. Spills, poor storage and static sparks during transfer are common causes of fires and explosions in plants, shops and warehouses.

Core Obligations

1. Classify Liquids by Category (1910.106(a)(19))

Category 1 liquids have a flashpoint below 73.4 °F (23 °C) and a boiling point at or below 95 °F (35 °C). Category 2 liquids have a flashpoint below 73.4 °F and a boiling point above 95 °F. Category 3 liquids have a flashpoint from 73.4 °F to 140 °F (60 °C). Category 4 liquids have a flashpoint above 140 °F and at or below 199.4 °F. Liquids heated to within 30 °F of their flashpoint must be handled as a more hazardous category.

2. Use Containers Within Size Limits (1910.106(d)(2) and Table H-12)

Table H-12 sets the largest container allowed for each category. Glass or approved plastic containers are limited to 1 pint for Category 1, 1 quart for Category 2 and 1 gallon for Categories 3 and 4. Metal containers other than DOT drums are limited to 1 gallon for Category 1 and 5 gallons for the others. Safety cans may hold 2 gallons of Category 1 liquid and 5 gallons of the others. DOT metal drums may hold 60 gallons and approved portable tanks 660 gallons for all categories.

3. Store Correctly in Cabinets (1910.106(d)(3))

A storage cabinet may hold no more than 60 gallons of Category 1, 2 or 3 liquids, or 120 gallons of Category 4 liquids. Cabinets must keep their internal temperature at or below 325 °F during a 10-minute fire test and be labeled in conspicuous lettering with the warning "Flammable" and "Keep Fire Away." Metal cabinets built from No. 18 gauge sheet iron, double walled with a 1½-inch air space, a three-point lock and a sill raised at least 2 inches are deemed to comply.

4. Build Inside Storage Rooms to Standard (1910.106(d)(4))

Inside storage rooms need a fire-resistive rating, liquid-tight floor-wall joints, approved self-closing fire doors, and noncombustible liquid-tight sills or ramps at least 4 inches high at openings to other rooms (or a floor at least 4 inches lower, or an open-grated trench drain). Table H-13 limits storage to between 2 and 10 gallons per square foot of floor area, depending on room size, fire rating and fire protection. Rooms need ventilation of at least six air changes per hour, one clear aisle at least 3 feet wide, and no stacking of containers over 30 gallons.

5. Limit Quantities in Industrial Plant Work Areas (1910.106(e)(2)(ii))

Outside a storage room or cabinet, the quantity in any one fire area of an industrial plant must not exceed 25 gallons of Category 1 liquids in containers, 120 gallons of Category 2, 3 or 4 liquids in containers, or 660 gallons of Category 2, 3 or 4 liquids in one portable tank.

6. Control Fire and Ignition Sources (1910.106(d)(7))

At least one portable extinguisher with a rating of not less than 12-B must be located outside a storage room door, no more than 10 feet away. Where Category 1, 2 or 3 liquids are stored inside a building but not in a storage room, at least one 12-B extinguisher must be placed between 10 and 25 feet from the storage area. Open flames and smoking are not allowed in flammable liquid storage areas, and water-reactive materials may not be stored in the same room.

7. Dispense and Transfer Safely (1910.106(e)(2)(iv) and (e)(6)(ii))

Category 1 and 2 liquids, and Category 3 liquids with a flashpoint below 100 °F, must be kept in covered containers when not in use. Transfers inside buildings must use a closed piping system, safety cans, a device drawing through the top of the container, or gravity through an approved self-closing valve. Transferring by pressurizing the container with air is not allowed. When these liquids are dispensed into containers, the nozzle and container must be electrically interconnected, for example by a bond wire.

Common Compliance Approaches

Build an Inventory by Category

List every flammable liquid with its category from the safety data sheet, its container type and where it is stored.

Set Point-of-Use Limits

Keep only small working quantities at workstations, within the fire area limits, and return the rest to cabinets at the end of the shift.

Example: Flammable Liquid Storage in Practice

A furniture finishing plant uses acetone and lacquer thinner, both Category 2. An audit finds 5-gallon metal cans of thinner on benches and a 55-gallon drum dispensed with an air-pressure pump. The plant moves bench stock into safety cans, keeps bench quantities well within the 120-gallon fire area limit for Category 2 liquids, installs two labeled 45-gallon cabinets, and replaces the air pump with a drum pump drawing from the top. Bond wires are added at the drum station and a 12-B extinguisher is mounted 15 feet from the cabinets.

Related regulations: OSHA HazCom, OSHA portable fire extinguishers, OSHA compressed gases.

Note: This summary focuses on containers, portable tanks and industrial plants. Section 1910.106 also covers tank storage, piping, bulk plants, service stations, processing plants, and refineries, chemical plants and distilleries. Paragraph (e) applies only where flammable liquids are incidental to the plant's main activity. Paragraph (j) excludes items such as bulk transportation, fuel oil tanks connected to oil burning equipment and storage on farms. State plan states may set stricter rules.

Frequently Asked Questions

How much can go in one flammable storage cabinet?

No more than 60 gallons of Category 1, 2 or 3 liquids, or 120 gallons of Category 4 liquids.

Does diesel count as a flammable liquid?

It depends on its flashpoint. Any liquid with a flashpoint at or below 199.4 °F is a flammable liquid under 1910.106. Check section 9 of the safety data sheet for the flashpoint and classification.

Are glass bottles allowed for solvents?

Only in small sizes. Table H-12 limits glass or approved plastic to 1 pint for Category 1 and 1 quart for Category 2, with narrow exceptions, for example where contact with metal would make the liquid unfit for use or corrode the container.