1 Scope

1.1 These requirements cover complete, self-contained strainer or filter assemblies intended for use with designated flammable and combustible liquids, anhydrous ammonia (fertilizer grade), and non-potable water. Flammable and combustible liquid strainers or filter assemblies are used in residential and commercial fuel-burning, dispensing, and handling facilities. Although these devices are designated as strainers, they may be either strainers or filters according to the common terminology of the industry.

1.2 The term flammable and combustible liquids as used in this standard means fuel oil, gasoline, kerosene, and similar petroleum products, liquefied petroleum gas (LP-Gas or propane), and manufactured and natural fuel gas.

1.3 These requirements do not cover the following:

1. a) Strainers for handling liquids under cryogenic conditions;

2. b) Strainers for marine use;

3. c) Strainers for automotive fuel lines;

4. d) Strainers for handling refrigerants;

5. e) Strainers for use in such facilities as chemical, petrochemical, petroleum, and utility power plants;

6. f) Strainers for use in fluid-power (hydraulic and pneumatic) applications;

7. g) Strainers for use with gasoline or gasoline/ethanol blends, which are covered under the Standard for Strainers for Gasoline and Gasoline/Ethanol Blends with Nominal Ethanol Concentrations up to 85 Percent (E0 – E85), UL 331A; and

8. h) Strainers for use with diesel fuel, biodiesel fuel, diesel/biodiesel blends, kerosene, or fuel oil, which are covered under the Standard for Strainers for Diesel Fuel, Biodiesel Fuel, Diesel/Biodiesel Blends with Nominal Biodiesel Concentrations Up to 20 Percent (B20), Kerosene, and Fuel Oil, UL 331B.

Summary of Topics

This Ninth Edition of ANSI/CAN/UL/ULC 331, Standard for Strainers for Flammable and Combustible Liquids, Anhydrous Ammonia and Non-potable Water, dated February 22, 2023 is a new joint Canada-US standard and reflects the latest ANSI and SCC approval dates and incorporates the proposals dated September 16, 2022.