1 Scope

1.1 These requirements cover complete, self-contained strainer or filter assemblies intended for use with the fuels designated in 2. Although these devices are designated strainers, they may be either strainers or filters according to the common terminology of the industry.

1.2 Strainers and filter assemblies covered by these requirements are intended for use with one or more of the following:

1. a) Diesel fuel, which includes renewable diesel, and diesel/biodiesel blends with nominal biodiesel concentrations up to 5 percent (B0 – B5) formulated in accordance with the Standard Specification for Diesel Fuel Oils, ASTM D975;

2. b) Diesel/biodiesel blends and renewable diesel/biodiesel blends with nominal biodiesel concentrations from 5 percent up to 20 percent (B6 – B20) formulated in accordance with the Standard Specification for Diesel Fuel Oil, Biodiesel Blends (B6 – B20), ASTM D7467;

3. c) Biodiesel (B99.9/B100) formulated in accordance with the Standard Specification for Biodiesel Fuel Blend Stock (B100) for Middle Distillate Fuels, ASTM D6751;

4. d) Kerosene formulated in accordance with the Standard Specification for Kerosine, ANSI/ASTM D3699;

5. e) Fuel oil (heating oil) formulated in accordance with the Standard Specification for Fuel Oils, ASTM D396.

1.3 These requirements do not cover the following:

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

2. b) Straniers 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 or filter assemblies for use with gasoline or gasoline/ethanol blends, which are covered under the Outline of Investigation for Strainers for Gasoline and Gasoline/Ethanol Blends with Nominal Ethanol Concentrations Up to 85 Percent (E0 – E85), UL 331A

8. h) Strainers or filter assemblies for use with LP-Gas, Natural Gas, Manufactured Gas, and Anhydrous Ammonia, which are covered under the Standard for Strainers for Flammable Fluids and Anhydrous Ammonia, UL 331.

Summary of Topics

This revision of ANSI/UL 331B dated October 1, 2020 includes the following changes in requirements:

– Revisions to 10-Day Moist Ammonia-Air Stress Cracking Test; Section 15

– Clarifications to the Deformation Test; 12.2, 12.5, and 12.6