Split-Spectrum White Paper June 2015 Nest Labs
Introduction Since residential smoke alarms were first popularized in the 1970s, home fires have changed: while it would generally take up to 30 minutes for a fire to take over a room in the 1970s, it can take as little as 5 minutes today. Today’s homes are bigger, with more open floor plans, more composite construction materials, and more polyurethane and synthetic furnishings which burn faster than materials used decades ago.
2. The Split-Spectrum Sensor enabled Nest Protect to sound a Heads-Up alert earlier on average than the other types of alarms tested during smoldering fires. 3. The Split-Spectrum Sensor enabled Nest Protect to sound a Heads-Up alert earlier on average than the photoelectric alarms tested during flaming fires. 4. In nuisance testing, Nest Protect had a lower overall alarm rate than other photoelectric, ionization, and combination photoelectric-ionization alarms tested.
wavelengths of light effectively (blue, red, and other visible wavelengths of light) which is why clouds appear white.12 13 Equipped with both blue and infrared light sources in its smoke chamber, Nest Protect can leverage this light-dependent particle scattering behavior to estimate the types and sizes of particles in the chamber. Nest Protect uses this information to make an informed decision about what to do next.
The smoldering wood, flaming liquid, flaming wood, and flaming paper tests were designed to follow the specifications of the corresponding UL 217 tests. The smoldering foam, broiling, toast, and frying tests were adapted from the tests designed by NIST. The smoldering Romex wires, flaming foam, and shower steam tests were designed by the outside testing facility.
Smoldering fire performance Other Photoelectric 105.1% Photo/Ion Combo 99.7% Ionization Only (See Note Below) 115.2% Nest Protect Emergency Alarm 100% 86.7% Next Protect Heads-Up 0 20 40 60 80 100 120 Smoldering Fires – Median Normalized Alarm Time* Ionization Note: Of the three Ionization-only alarms tested, during smoldering cable and smoldering foam fire tests, two ionization-only alarms did not sound. The third ionization alarm sounded in only 60% of the tests.
Flaming Fire Performance Other Photoelectric 97.7% Photo/Ion Combo 82.7% Ionization Only (See Note Below) 83.6% 100% Nest Protect Emergency Alarm 94.6% Next Protect Heads-Up 0 20 40 60 80 100 120 Flaming Fires – Median Normalized Alarm Time* The tests included multiple instances of four different types of flaming fires: flaming foam, flaming wood, flaming liquid, and flaming paper.
Based on more than 200 datasets, the results of these tests included the following: Nest Protect Emergency Alarm Photoelectric Photo/Ion Combo Ionization 0 Total Alarm Over All Tests 20 40 60 % of Emergency Alarms Boiling Toasting 80 Frying 100 Shower Steams Nuisance Testing While nearly all tested alarms responded to broiling frozen hamburgers as emergency smoke events, Nest Protect did not alarm during nuisance toast and shower steam tests.
Conclusion With the addition of a blue LED to complement an infrared LED, Nest’s Split-Spectrum Sensor can collect more information about particles of varying sizes in the room and make more informed alarm decisions with the potential for improved rejection of nuisance alarms. In Nest’s initial testing, the Split-Spectrum Sensor’s median Heads-Up warning time for smoldering fires was faster than other devices’ time to alarm.
ODM ODM ODM ODM t. 10 f t. f .7 17 Fire Source 22 ft. Fire Testing Room Configuration (ODM is a reference obscuration meter) 10 22 ft.
S S 4 ft. S Door 4 ft. S 3 ft. L L L 3 ft. L 8 ft. Door S S . 10 f t S Stove 17 ft. 5 ft. Shower 9 ft. S L t. L 6f L L 17 ft.
Smoldering Fires 141.1% Combo Detectors 182.5% Other Photo Detectors 100% Nest Protect Emergency Alarm 85.0% Next Protect Heads-Up 0 50 100 150 200 Smoldering Cable – Median Normalized Alarm Time* 984.6% Ionization Detectors 100% 85.
104.8% Combo Detectors 117.7% Other Photo Detectors 100% Nest Protect Emergency Alarm 97.3% Next Protect Heads-Up 0 20 40 60 80 100 120 140 Smoldering Foam – Median Normalized Alarm Time* 623.0% Ionization Detectors 0 100% Nest Protect Emergency Alarm 97.
85.3% Combo Detectors 89.9% Other Photo Detectors 100% Nest Protect Emergency Alarm 86.2% Next Protect Heads-Up 0 20 40 60 80 100 120 Smoldering Wood – Median Normalized Alarm Time* 113.1% Ionization Detectors 100% Nest Protect Emergency Alarm 86.
Flaming Fires 92.8% Other Photoelectric Detectors 100% Nest Protect Emergency Alarm 95.8% Next Protect Heads-Up 0 20 40 60 80 100 120 Flaming Paper – Median Normalized Alarm Time* 97.6% Other Photoelectric Detectors 100% Nest Protect Emergency Alarm 96.
92.8% Other Photoelectric Detectors 100% Nest Protect Emergency Alarm 77.5% Next Protect Heads-Up 0 20 40 60 80 100 120 Flaming Liquid – Median Normalized Alarm Time* 104.4% Other Photoelectric Detectors 100% Nest Protect Emergency Alarm 85.
Nuisance Testing Shower Steam Nest Protect Ionization Combination Photoelectric + Ionization Photoelectric 0% 0 Alarms /10 Tests 0% 0 Alarms /27 Tests 30% 8 Alarms /27 Tests 81% 22 Alarms /27 Tests Frying Toasting 38% 0% 3 Alarms /8 Tests 0 Alarms /6 Tests 63% 83% 10 Alarms /16 Tests 10 Alarms /12 Tests 25% 100% 4 Alarms /16 Tests 12 Alarms /12 Tests 25% 0% 5 Alarms /16 Tests 0 Alarms /12 Tests 17 Broiling 100% 6 Alarms /6 Tests 100% 12 Alarms /12 Tests 100% 12 Alarms /12 T
