1 Scope

1.1 These requirements cover hose and hose assemblies in sizes up to and including a nominal internal diameter of 4 in (102 mm) for conveying liquefied petroleum gas (LP-Gas) intended to be installed in closed systems in compliance with the Standard of the National Fire Protection Association Liquefied Petroleum Gas Code, NFPA 58. The hose or hose assembly is intended for a maximum working pressure of 350 pounds per square inch gauge (psig) (2400 kPa) for use at temperatures within the range of minus 40°C (minus 40°F) to plus 60°C (140°F), or minus 54°C (minus 65°F) to plus 60°C. Hose and hose assemblies in sizes larger than 2 in (50.8 mm) are not intended for use on reels.

1.2 This standard does not apply to:

1. a) Flexible hose connectors for LP-Gas that are investigated under the Standard for Pigtails and Flexible Hose Connectors for LP-Gas, UL 569;

2. b) Gas appliance connectors for handling fuel gases at 5 psig (34.5 kPa) or less, which are investigated under Connectors for Gas Appliances, ANSI Z21.24, nor to metallic hose intended for use in oil transportation piping, in petroleum refinery piping, or in gas transmission and distribution piping systems; or

3. c) Hose intended for use in automotive applications or hose intended for use in confined areas.

4. d) Hose assemblies that are investigated under Gas Hose Connectors for Portable Outdoor Gas-Fired Appliances, ANSI Z21.54.

Summary of Topics

This revision to ANSI/UL 21 dated November 8, 2022 includes the following changes in requirements:

– Addition of exceptions for additional connection fittings and corresponding marking requirements; 7.6, 7.8, 22.9 and 22.10

– Clarification for radius of bend and center distance for test; Table 14.1

– Updating referenced standards; 20.4