The ionization sensors are used to detect the small particles from fast burning fires, but because of their nature, they’re more prone to false alarms these type of sensors are usually found built into older smoke detectors. The photoelectric sensors can detect larger particles, so it is a lot more useful for smouldering fires those which have not yet erupted into flames, so they’re better for an early detection and are less likely to trigger false alarms. The First Alert P1010 uses the aforementioned technology, so it has a beam of light inside a small chamber which does not directly hit the photoelectric sensor, but, the moment smoke particles enter the device through the holes in the metallic section, the light gets diverted and it will immediately hit the sensor, thus sounding the alarm. In case a fire is detected, you will be able to hear three beeps, pause, three beeps, pause and repeat, while the LED light will flash rapidly – the LED is located inside the Silence / Test button the horn is loud, reaching up to 85 db, 10 feet away from the device – if you have a hearing impairment, it is advisable to have a look at smoke alarms with built in strobes. 1. Which type of sensors are equipped on the smoke detectors?Smoke detectors can have two types of sensors: ionization sensors, photoelectric sensors or both usually called dual sensors.