Ordinary smoke alarms can only do one thing
Defending against fire is a chief concern for homeowners, and smoke detectors perform a vital role in shielding your family. Even so, smoke detectors have some limitations. For example, they are only able to react to smoke, not extreme temperatures. In the event there is a fire in your residence, you may not be cautioned unless the smoke ascends to the smoke detector. Although there are further telltale indications of fire -- such as a sharp increase in warmth -- if there’s a lack of smoke, there is no sounding of your smoke detector.
Additionally, smoke detectors only beep if they encounter ample smoke. When a fire creeps along slowly at first, you might not be warned until the flames are out of control. Many smoke detectors employ more than one sensor, which means they will be able to perceive smoke from both a blazing inferno and something less intense. If they start beeping, it's up to the homeowner to contact first responders after they safely leave the residence.