In a Lindberg fire detection system, what happens when the detector tube heats up?

In a Lindberg fire detection system, what happens when the detector tube heats up?

• A. Gas is released and the pressure drops.
• B. Gas escapes reducing volume.
• C. The heating has no effect until a threshold.
• D. Gas is released from the inert gas, increasing pressure, which activates a pressure switch.

Answer: (D)

In this type of detector, the element is a sealed tube filled with inert gas at a small overpressure. When the tube is heated by heat from a fire, the gas expands and/or is released from its reservoir inside the detector, causing the pressure inside the tube to rise. That pressure increase acts on a diaphragm or piston that drives a pressure switch; once the gas pressure reaches the preset threshold, the switch closes and a fire warning signal is sent. So the key idea is that heating raises internal pressure by releasing gas, and this pressure rise activates the switch to trigger the alarm.

In this type of detector, the element is a sealed tube filled with inert gas at a small overpressure. When the tube is heated by heat from a fire, the gas expands and/or is released from its reservoir inside the detector, causing the pressure inside the tube to rise. That pressure increase acts on a diaphragm or piston that drives a pressure switch; once the gas pressure reaches the preset threshold, the switch closes and a fire warning signal is sent. So the key idea is that heating raises internal pressure by releasing gas, and this pressure rise activates the switch to trigger the alarm.