The latest version of the UL standard for smoke detectors is designed to help ensure that devices can both detect a wider variety of fires, and avoid generating a nuisance alarm when there is not an emergency. Many manufacturers are making key changes to their smoke detectors in order to meet the new requirements, and, as Brian Boisse, senior engineering manager for fire system manufacturer Mircom, explains, they will be prohibited from manufacturing devices that don’t meet the new requirements after June 30, 2021.

New Requirements

The new requirements apply to standalone smoke detectors, or smoke alarms, as well as smoke detectors which are designed to be used as part of a complete life safety system. UL standard 217 applies to smoke alarms and UL standard 268 applies to the smoke detector system devices SDM readers most commonly install. The specific designation of the new 268 standard is Version 7.

Ultimately, where and how soon a dealer must install new devices that meet the standards will depend on which version of the National Fire Protection Association (NFPA) 72 standard an individual’s jurisdiction has adopted. That standard is typically updated every three years, but some jurisdictions take years to adopt the latest version.

According to SDM Columnist Roy Pollack, the current version of NFPA 72 doesn’t require smoke detectors to meet UL 268 Version 7. The next version of the NFPA standard will carry the year 2022 designation and committees are still in the process of deciding whether to require Version 7 detectors in the standard, observes Pollack, who works as the director of training and compliance for Comcast/Xfinity Home.

Although Vaughan, Ontario-based Mircom doesn’t make smoke detectors, the company does offer systems that work with those detectors, and Boisse is quite knowledgeable about smoke detectors through his involvement in industry standards development.

One key new key requirement from Version 7 that Boisse points out is immunity from cooking nuisance alarms. Also known as the “hamburger test,” this requires smoke detectors to not generate an alarm signal from cooking nuisances that may create smoke signatures.

Another new requirement is the detection of fires involving polyurethane, a type of stuffing used in modern furniture. Two separate tests are required for this — one involving flaming polyurethane and the other involving smoldering polyurethane.

“With the increase in synthetic materials used within building spaces, fires simply burn and move faster than ever before, often with low smoke levels, and detectors need to be held to higher standards,” says Kris Cahill, offering management lead for Honeywell Building Technologies.

The flaming polyurethane test replaces a previous test that sought to confirm that a detector could identify a liquid heptane fire characterized by black smoke, Boisse notes.

Tests that were required for UL 268 Version 6 that will still be required under Version 7 include a burning paper test, a smoldering wood test and a test that involves flaming wood piled in a crib and a heater that generates smoke.

The new version of UL 268 requires all smoke detectors to be tested at a UL-approved laboratory. At press time in August, the majority of devices on the market still had not received final approval but were somewhere in the redesign and testing process, which is taking longer than anticipated because of the COVID-19 crisis.

“There’s a mad rush to get to UL and get through it,” says Craig Summers — vice president of sales for the fire and security division of St. Louis-based manufacturer Potter Electric Signal.

Passing the New Tests

Manufacturers are required to submit a description to UL of how their smoke detectors meet these testing requirements, Boisse explains.

Redesigning products to meet the new testing requirements typically involves changing the algorithm used to detect alarms, he adds. Some manufacturers may opt to put multiple sensors inside the device, and use logic to determine the specific conditions each sensor must detect to generate an alarm.

Photoelectric smoke detectors that use multiple wavelengths are one way to pass Revision 7 testing by adding further capabilities of determining smoke signatures.

“Usually multiple wavelengths are infrared and blue, which are at opposite ends of typical LED spectrums,” says Boisse. “[These different wavelengths] behave differently with different particle sizes and refractive indexes. This can help to determine smoke particle makeup as well as avoid false alarms from other nuisance sources such as water vapor, steam or aerosols.”

Zeeland, Mich.-based smoke detector manufacturer Gentex Corporation was most of the way through the Version 7 testing process when we talked to Dave Christian, Gentex director of business development, in August.

Gentex offers several different types of smoke detectors, including some that will meet Version 7 requirements by using two optical sensors, and others that will use multiple other technologies.

At press time, Honeywell also was in the process of obtaining Version 7 approval for some of its some detectors, while others had already received approval. Cahill says that Honeywell will offer both single sensor photoelectric detectors and multi-criteria detectors capable of meeting the new standards to lower false alarms and increase response time.

Want to know if a smoke detector has received UL 268 Version 7 approval? UL maintains a searchable database of approved products on the UL Product IQ website, www.ul.com/apps/product-iq.