UL 711: Rating and Fire Testing

Performance testing and rating standards for UL Listed fire extinguishers

Last updated: September 21, 2025

Overview Fire Classifications Rating System Testing Procedures Performance Requirements UL 711 Rated Products

Overview

UL 711 establishes the rating and fire testing requirements for portable fire extinguishers. This standard determines the fire-extinguishing potential of extinguishers through standardized fire tests, providing the basis for the familiar rating classifications (like 2-A:10-B:C) seen on UL Listed extinguishers.

Terminology Note: Technical specifications and building codes may reference "ANSI/UL 711" (the formal designation with ANSI approval), while fire extinguisher labels show "UL Listed" with the rating (e.g., "2-A:10-B:C"). Both refer to the same standard - the ANSI prefix simply confirms national recognition.

The current edition (Edition 8) was published August 6, 2018, and works in conjunction with NFPA 10 for installation requirements.

Fire Classifications

UL 711 covers testing for all major fire classifications:

Class A: Ordinary combustibles (wood, paper, fabric, plastics)
Class B: Flammable liquids and gases (gasoline, oil, grease)
Class C: Energized electrical equipment
Class D: Combustible metals (magnesium, sodium, titanium)
Class K: Cooking oils and fats in commercial kitchens

Each class requires specific test fires and performance criteria to achieve certification.

Rating System

The UL 711 rating system indicates extinguishing capability:

Class A Rating: Numbers from 1-A to 40-A, where the number indicates relative extinguishing potential (e.g., 2-A extinguishes twice as much as 1-A)
Class B Rating: Numbers from 1-B to 640-B, indicating square feet of flammable liquid fire that can be extinguished
Class C Rating: No numerical rating; indicates suitability for electrical fires
Class D Rating: Tested on specific metals; no numerical rating system
Class K Rating: Pass/fail for commercial cooking equipment fires

Example: A 4-A:20-B:C rated extinguisher can handle Class A fires four times larger than 1-A, Class B fires up to 20 square feet, and is safe for electrical fires.

Testing Procedures

Fire testing under UL 711 includes:

Class A Tests: Wood crib and excelsior fires of varying sizes
Class B Tests: Flammable liquid pan fires with specified areas
Discharge Tests: Complete discharge time and range measurements
Operator Safety: Testing for heat exposure and visibility during use
Re-ignition Tests: Monitoring for fire rekindling after extinguishment
Conductivity Tests: For Class C rating qualification
Multiple Operators: Tests conducted by different operators for consistency

Performance Requirements

To achieve UL 711 ratings, extinguishers must:

Successfully extinguish test fires within specified parameters
Demonstrate consistent performance across multiple tests
Maintain minimum discharge duration (8 seconds for most portable units)
Achieve effective throw distance for operator safety
Prevent re-ignition for specified observation periods
Meet electrical conductivity limits for Class C ratings (less than 1.00 milliampere)
Pass supplemental tests for special hazards (e.g., deep-seated Class A fires)

The standard also includes provisions for testing extinguishers intended for residential use (UL 711A) with specific requirements for cooking equipment fires.