What is UL 2167A?

UL 2167A is the UL standard used to certify Automist, formally titled Outline of Investigation for Targeting Water Mist System Units for One- and Two-Family Dwellings for Fire Protection Service. It was developed to address a new category of electronically controlled, targeted watermist systems that did not previously fit within traditional sprinkler or nozzle standards.

At its core, UL 2167A builds on established UL watermist principles, where systems are evaluated for their ability to “control, extinguish, or suppress fire” and to meet “minimum fire-protection performance, construction, and marking requirements” . For residential applications, this means demonstrating that a system can intervene early in a fire and reduce the risk of injury and life loss.

UL 2167A applies specifically to wall-mounted, targeted systems for one- and two-family dwellings, including manufactured homes. These systems are electronically controlled, meaning they detect and respond to fire conditions rather than relying on passive thermal activation alone. However, they are still classified as supplemental fire protection, not a replacement for smoke detection or alarm systems, and are installed in accordance with NFPA 750.

What distinguishes UL 2167A is the depth of performance-based testing required. Systems must demonstrate effectiveness in realistic fire scenarios, including cooking fires, by proving they can limit fire growth and thermal conditions. This aligns with UL’s definition of fire control as “limiting the growth of a fire and controlling ceiling gas temperatures to prevent structural damage” and fire suppression as “the sharp reduction of the heat release of a fire and the prevention of its regrowth” . Automist’s certification includes multiple real cooktop fire tests using canola oil heated to autoignition, reflecting these requirements.

Performance is not just about extinguishing flames, but about how water is delivered. UL standards require detailed verification of spray characteristics, including droplet size, distribution, and flow behaviour. For example, watermist systems must be characterised by “water droplet size and velocity” and distribution across multiple measurement locations to ensure consistent fire interaction . This is critical because the effectiveness of watermist depends on fine droplets absorbing heat and displacing oxygen locally.

UL 2167A also ensures reliability under real-world conditions. Systems are subjected to extensive durability testing, including pressure, corrosion, and environmental exposure. Components must withstand conditions such as hydrostatic pressure without rupture or leakage and continue to operate after exposure to heat, humidity, and contaminants . Functional testing further verifies that systems activate and discharge as intended within defined timeframes.

Finally, UL certification under UL 2167A provides a recognised, independent basis for approval. For Authorities Having Jurisdiction (AHJs) and insurers, it demonstrates that the system has been rigorously tested against defined safety and performance criteria. It also confirms that the system performs under worst-case installation and operating conditions, as required by UL methodologies.

You can confirm Automist’s UL Listing under File Number EX29276 on the UL Product iQ database.

For additional documentation, including UL certification details and fire test reports, contact Plumis or refer to our Automist UL System Certificate.