What type of alarm is less effective for gasoline and alcohol fires?

Photoelectric alarms are designed to detect smoldering fires, which usually produce a lot of smoke and may be associated with materials like wood or upholstery. When it comes to gasoline and alcohol fires, these tend to burn very quickly and can create less visible smoke. Because of this, photoelectric alarms may not be as effective in detecting these types of fast-burning, flammable liquid fires.

Ionic alarms, on the other hand, can pick up the ionization changes caused by flames and smoke particles, making them better suited for quicker or more explosive types of fires. Combination alarms often use both photoelectric and ionization technologies, which would give them a broader range of detection capabilities. Heat detectors are designed to respond to rises in temperature, making them effective for quick ignition fires, including those fueled by gasoline and alcohol.

Thus, while photoelectric alarms are great for detecting smoldering materials, they fall short in scenarios where fires occur from highly flammable liquids, which burn rapidly and may not generate the kind of smoke that these alarms are optimized to detect.