UL 139

Outline of Investigation for Medium- and High-Expansion Foam-Extinguishing System Equipment and Concentrates

1.1 These requirements cover foam liquid concentrates, proportioning equipment, and discharging equipment for producing foam intended for fire extinguishment or control. For medium-expansion foam, the expansion ratio is 20:1 to 200:1. For high-expansion foam, the expansion ratio is 200:1 to approximately 1000:1. These requirements are based on the premise that a specific foam liquid concentrate shall be investigated for use with the intended foam equipment.

1.2 Requirements for the design, installation, operation, testing, and maintenance of foam systems for fire protection are included in the Standard for Low-, Medium-, and High-Expansion Foam, NFPA 11.


  • Edition Number: 6
  • Edition Date: 01/24/2014
  • Price Code: A
  • Type: outline
  • ANSI Approved:
  • DOD Approved: