Acoustic fire suppression goes commercial.
In a makeshift demonstration kitchen in Concord, California, cooking oil splatters in and around a frying pan, which catches fire on an unattended gas stove. Within moments, a smoke detector wails. But in this demonstration, something less common happens: An AI-driven sensor activates and wall emitters blast infrasound waves toward the source of the fire in an attempt to put it out.
The science of acoustic fire suppression, which has long been known and documented in scientific literature and the press, works by vibrating oxygen molecules away from a fuel source, depriving the fire of a critical component needed for combustion.
Indeed, after just a few seconds of infrasound, the tiny kitchen blaze goes out.
The demonstration I witnessed took place in the presence of numerous firefighters and officials from Contra Costa County Fire Protection District, the state’s premier wildland firefighting agency (CAL FIRE), and invited journalists.
“We were able to not just point-and-shoot like a fire extinguisher; we figured out how to run it through ducting and distribute it like a sprinkler system,” said Geoff Bruder, co-founder and CEO of Sonic Fire Tech, during the presentation.
The company’s goal is to replace sprinklers, which are effective at stopping fires but can also do significant water damage to a property. Sonic Fire Tech appears to be the first company trying to commercialize the science of acoustic fire suppression. Its executives have already been touring Southern California; Wednesday’s event was the first in the northern half of the state.
The company aims to make this infrasound technique mainstream in both commercial (for instance, a data center, where sprinklers would damage electronics) and in-home installations, given that sprinklers are already required in all new California homes built in 2011 and later.
Sonic Fire Tech also hopes to produce a backpack-based system that could be worn by wildland firefighters headed out into the field.
“We are making meaningful technological improvements on a monthly basis,” Stefan Pollack, a company spokesperson, emailed Ars after the event.
But two experts who spoke with Ars raised serious questions about the potential for this technology to supplant traditional sprinklers in a home. They are even more skeptical as to whether the technique can be effective in an uncontrolled wildfire situation, where flames can grow very quickly.
The infrasound system in action
Sprinkler replacement?
Sonic Fire Tech says that its system is as good as, if not better than, traditional sprinklers for many applications.
“Sonic Fire Tech is in fact intended to replace interior residential sprinklers,” Pollack told Ars. “The demo showed a critical benefit of SFT over water sprinklers in suppressing a kitchen fire, which represents about half of all residential fires. This is also applicable to commercial kitchen fires and other common grease and chemical fire applications.”
The company’s press releases tout infrasound’s advantages over sprinklers. “Traditional residential sprinklers activate several minutes only after heat rises to a threshold, can discharge large volumes of water that damage interiors and electronics, and require plumbing infrastructure that adds cost and complexity,” says one release. “Sonic Home Defense, by contrast, deploys in milliseconds and uses inaudible low-frequency infrasound waves to disrupt the chemistry of combustion before flames can spread, with no water, no chemicals, and no risk of flooding the interior of the home being protected.”
The goals sound great, but they do raise questions among outside observers.
“Sprinklers have a well-established role,” Nate Wittasek, a Los Angeles-based fire protection engineer, emailed Ars. “They apply water directly to the fuel, cool the space, slow or stop flashover, and give people time to get out while reducing risk to firefighters. Sound may knock down a small flame, but it does not cool hot surfaces or wet fuel. That raises real questions about re-ignition, smoldering fires, hidden fires, and fires that are partially blocked by contents.”
Water sprinklers have been around for a long time. The National Fire Protection Association (NFPA), a well-known industry nonprofit, was founded in the late 1800s to develop a uniform standard for sprinklers. The latest iteration of those guidelines, known as the “13D” standard, is well documented and widely adopted.
A recent press release from Sonic Fire Tech states that the company has “secured third-party validation of its system as a viable NFPA 13D-equivalent alternative to conventional residential sprinklers.”
The company told Ars that it has been evaluated by James Andy Lynch (who was present at the demonstration) and his team at Fire Solutions Group, a Pennsylvania-based consultancy, to establish Sonic Fire Tech’s bona fides.
Sonic Fire Tech declined to provide Ars with a full copy of Lynch’s report, citing “confidential and patent-pending information,” but it did send Ars the two-page executive summary.
This document states that “the Sonic Fire Tech system is capable of delivering extremely rapid fire detection, meaningful suppression or extinguishment, and consistent performance across a variety of installation configurations.”
But the summary lacks any kind of detailed explanation of which tests were run and under what conditions. It also concludes that “additional testing and optimization are recommended to further expand the range of validated applications,” adding that Sonic Fire Tech’s products have the “potential to complement or, in certain applications, serve as an alternative to traditional suppression systems.”
“Equivalency [to the 13D standard] can only be approved by the appropriate authority having jurisdiction and requires technical documentation be submitted demonstrating the equivalency,” Jonathan Hart, NFPA Technical Lead, Fire Protection Technical Resources, emailed Ars.
To date, Sonic Fire Tech has not publicly provided this information.
Wittasek said that if Sonic Fire Tech is going to claim that its product is as good as or better than the NFPA 13D standard, it should be able to provide a whole range of specifics, such as “who validated it, what test protocols were used, what fire scenarios were included, and how success was defined.”
“I would want to see full-scale testing that includes typical residential fires like furniture and mattress fires, cooking fires, electrical fires, and attic or exterior ember exposures,” he added. “It should also cover different conditions like open and closed doors, varying ceiling heights, crosswinds, obstructed fuel packages, and whether the fire comes back after the system shuts off.”
Similarly, Michael Gollner, a professor of mechanical engineering at the University of California, Berkeley, and an expert in fire dynamics, told Ars there’s simply not enough information yet to show that this technology works better than sprinklers.
He pointed to a 2018 academic paper, which found that “acoustics alone are insufficient to control flames beyond the incipient stage.”
By contrast, “Fire sprinklers are extensively tested and certified by standards developed by the fire safety community over many years,” he emailed Ars. “I think this product needs to demonstrate the same or better performance with the same reliability before it can be considered to replace any existing safety measure. While I am absolutely supportive of out-of-the-box thinking, lives are truly at stake, and new technologies must carefully demonstrate effectiveness and reliability before being entrusted by society.”
Dozer time
As for the Contra Costa County firefighters who hosted the demonstration, they are curious to see more. Deputy Fire Chief Tracie Dutter told Ars that the agency does not recommend specific products, but it does try to understand the uses that new technology can have.
“Sonic representatives indicated they are exploring opportunities to partner with fire departments to test this technology on a bulldozer,” Dutter said.
“The District would be open to testing this system on one of our dozers,” Dutter added, to “better understand its limitations and potential failure points.”
With new tech like this, firefighters also want to understand what “long-term maintenance requirements” it has, whether “routine testing or calibration is required to ensure reliability,” and “how system failures such as a malfunctioning detector or acoustic generator are identified and communicated to an owner.”
