Follow these requirements for flammable and combustible liquids storage because the vapours of flammable liquids ignite and burn easily, strict storage requirements are essential.
Flammable and Combustible Liquids Overview
Flammable and combustible liquids present a danger of personal injury and property damage, so strict storage requirements are both essential and required by law.
Facts about flammable and combustible liquids
- Flammable and combustible liquids ignite easily and burn with extreme rapidity.
- Flammability is determined by the flash point of a material.
- Flashpoint is the minimum temperature at which a liquid forms a vapour above its surface in sufficient concentration that it can be ignited.
- Flammable liquids have a flash point of less than 100°F. Liquids with lower flash points ignite easier.
- Combustible liquids have a flashpoint at or above 100°F.
- The vapour burns, not the liquid itself. The rate at which a liquid produces flammable vapours depends upon its vapour pressure.
- The vaporization rate increases as the temperature increases. Therefore, flammable and combustible liquids are more hazardous at elevated temperatures than at room temperature.
- Class 1 Flammable Liquids must be bonded and grounded when transferring liquids.
Restrictions and guidelines
Because their vapours ignite and burn easily, flammable and combustible liquids have strict storage requirements. The hazard classification of a liquid determines the type and size of the container in which it can be stored. For more information, see:
- Container size and quantity limits
- Flammable and combustible liquids storage guidelines
Hazard classifications
National Fire Protection Association (NFPA) hazard classifications for flammable and combustible liquids are listed below:
| Hazard classification for flammable liquids | |||
|---|---|---|---|
| Class | Flash point | Boiling point | Examples |
| I-A | below 73°F (23°C) | below 100°F (38°C) | diethyl ether, pentane, ligroin, petroleum ether |
| I-B | below 73°F (23°C) | at or above 100°F (38°C) | acetone, benzene, cyclohexane, ethanol |
| I-C | 73-100°F (24-38°C) | —- | p-xylene |
| Hazard classification for combustible liquids | |||
| II | 101-140°F (39-60°C) | —- | diesel fuel, motor oil, kerosene, cleaning solvents |
| III-A | 141-199°F (61-93°C) | —- | paints (oil base), linseed oil, mineral oil |
| III-B | 200°F (93°C) or above | —- | paints (oil base), neatsfoot oil |
Flammable and Combustible Liquids Container Size and Quantity Limits
The hazard classification of a liquid determines the type and size of the container it may be stored in.
Chart 1 – Containers
Chart 1 describes the maximum type and size of container you are allowed to store based on the liquid’s hazard classification.
Chart 1: Maximum container size by hazard class | |||||
| Container Type | Class I-A | Class I-B | Class I-C | Class II | Class III-A – B |
|---|---|---|---|---|---|
| Glass1 | 1 pint (0.47L) | 1 quart (0.94L) | 1 gallon (3.79L) | 1 gallon (3.79L) | 1 gallon (3.79L) |
| Metal or listed, approved plastic | 1 gallon (3.79L) | 5 gallon (18.95L) | 5 gallon (18.95L) | 5 gallon (18.95L) | 5 gallon (18.95L) |
| Approved plastic | 0 gallon | 0 gallon | 0 gallon | 0 gallon | 5 gallon (18.95L) |
| Safety cans | 2 gallon (7.58L) | 2 gallon (7.58L) | 2 gallon (7.58L) | 5 gallon (18.95L) | 5 gallon (18.95L) |
| Polyethylene | 0 gallon | 0 gallon | 0 gallon | 60 gallon (227.4L) | 60 gallon (227.4L) |
| Metal drums | For storage requirements:
| 60 gallon (227.4L) | 60 gallon (227.4L) | ||
1Exceptions may be made to this requirement for storage of Class I-A and I-B liquids with approval from EH&S Fire & Life Safety, (858) 822-5706. Quantities may not exceed 1 gallon (3.79L).
Chart 2 – Quantity
Chart 2 describes the allowable total quantity of flammable or combustible liquid that may be stored in a UCSD facility.
Chart 2: Maximum quantities (Article 79 California Fire Code) | ||
| Flammable liquids | ||
| Location | Maximum amount | Container size |
|---|---|---|
| Open lab or shop (including safety cans) | 10 gallons (37.9L) | Comply with Chart 1 |
| Listed and approved flammable storage cabinet | 60 gallons (227.4L) | |
Selecting a Storage Container
- Store flammable liquids in a flammable storage cabinet. A variety of commercially manufactured cabinets are available.
- When flammable liquids must be stored outside a flammable storage cabinet, use approved safety cans whenever possible. They have spring-loaded lids and an internal screen which prevents combustion of the contents.
- Do not use large polypropylene (“Nalgene”) containers with stopcocks or valves at the bottom to store flammable liquids. These valves frequently leak and are unsafe in a fire.
- Never store flammable liquids in a standard or domestic refrigerator or freezer. Flammable liquids that must be chilled or frozen require specially designed “spark-proof” refrigerators or freezers.
Choose an Appropriate Location
- Avoid storing flammable liquids on high shelves or in direct sunlight.
- Store flammable liquids in a well-ventilated area.
- Caution: Never use environmental rooms (also called cold/ warm rooms) to store flammable, combustible, or other hazardous materials. Environmental rooms have many ignition sources and little or no outside air circulation. You can use small quantities of flammable or hazardous materials (500 ml) in these spaces, but do not store them there.
Transfering Material
- Transfer flammable and combustible liquids within a chemical fume hood when possible, and in a proper dispensing location such as a high hazard room (also called a flammable room).
- Wear appropriate PPE (i.e., Nomex® lab coat, goggles and face shield, gloves, non-synthetic clothing) when transferring material.
- Use proper bonding and grounding techniques (see Bonding and grounding below) when transferring Class I Flammable Liquids.
- Avoid contaminating either vessel during transfer.
Bonding & Grounding
Bonding and grounding is the process of providing an electrically conductive path between a dispensing container, a receiving container, and an earth ground. This pathway eliminates the potential buildup of static electricity and possible spark that can cause a flash fire if there is a flammable mixture of fuel and air.
- See a diagram of a bonded and grounded configuration.
Read about applicable requirements and definitions, and how to ground and bond below. Glass containers are excluded.
Requirement
Class 1 Flammable Liquids must be bonded and grounded when transferring liquids in accordance with Code of Federal Regulations, 29 CFR 1910.106(e)(6)(ii):
“Grounding.” Class I liquids shall not be dispensed into containers unless the nozzle and container are electrically interconnected. Where the metallic floorplate on which the container stands while filling is electrically connected to the fill stem or where the fill stem is bonded to the container during filling operations by means of a bond wire, the provisions of this section shall be deemed to have been complied with.”
Definitions
- Bonding is the process of connecting 2 or more conductive objects together by means of a conductor so that they are at the same electrical potential, but not necessarily at the same potential as the earth [NFPA 77 – 3.1.2].
- Grounding is the process of bonding 1 or more conductive objects to the ground, so that all objects are at zero (0) electrical potential; also referred to as “earthing” [NFPA 77 – 3.1.10].
- Grounding plate is a metal plate used to provide a bond for the receiving container.
- Grounding rod is an easily cleaned nonreactive metal rod designed to provide a bonding point for containers that are too small or that have no metal attachment point.
- Static electric discharge is a release of static electricity in the form of a spark, corona discharge, brush discharge, or propagating brush discharge that might be capable of causing ignition under appropriate circumstances [NFPA 77 3.1.16].
How to bond and ground
- See Lab Safety Supply’s Bonding and Grounding Fact Sheet for a good overview reference.
- Carefully assess and identify a safe location, avoiding:
- Poorly ventilated spaces
- Open flames or heat sources (e.g., hot plates, Bunsen burners etc)
- Electrically charged equipment
- Transfer flammable liquids within a chemical fume hood when possible and in a proper dispensing location such as a high hazard room (flammable room) or well-ventilated laboratory room.
- Use proper bonding and grounding cables:
- Plastic coated 10′ coiled grounding cable with clamps on both ends work well (see image below). Some locations may have permanent cables available.
- Braided 3′ bonding cable with alligator clips on both ends work well (see image below).
- Find an earth ground (copper water lines work well) and label it for future reference. Do not use fire sprinkler lines!
- Remove dirt, debris, paint, etc., to ensure a good metal to metal connection.
- Connect the dispensing vessel to the earth ground.
- Place receiving vessel in a secondary container or on a bonding metallic floorplate.
- Connect the bonding cable from the receiving vessel to the dispensing vessel or floorplate (metal to metal).
- Note: If the receiving container is too small, does not have a metal connection, or you do not have a metal floorplate, provide a grounding rod (use care that it does not tip over).
- Once properly connected, proceed with your transfer.
- When complete, disconnect all bonding and grounding cables and remove the grounding rod if applicable.
- Clean all equipment and properly transport the material to the laboratory.
- Leave the bonding and grounding equipment readily available for the next person to use.
2 examples of bonding and grounding configurations.
