what does 1-alarm mean in a fire?
A sensor is a general term for any device that detects something. A sensor might be a light sensor, there are radon sensor that detect radon in a home's basement, or motion sensors that detect motion. Smoke detectors are a type of sensor that detects smoke particles in the air, or carbon monoxide. A thermometer is a sensor of heat energy. It's a sensor that measures the amount of heat around the device, and usually has some sort of means to display the measurement of heat to an observer. The oldest (or at least the earliest of modern times) and simplest of thermometers is the expansion of mercury in a vacuumed glass tube.
The most obvious cause would be having the cylinder facing the wrong way. Is the beveled edge facing inward when closing, as it should be? Is the cylinder being blocked from coming completely out when the door is closed? Either by the strike being positioned too far forward or the hole not being deep enough.
