Which sensor is used in cylinder-head temperature indicators?

Which sensor is used in cylinder-head temperature indicators?

• A. Thermocouple
• B. Bourdon tube
• C. Capacitance sensor
• D. Strain gauge

Answer: (A)

Cylinder-head temperature indicators rely on a thermocouple to measure heat directly from the engine head. A thermocouple uses the thermoelectric effect: two dissimilar metals joined at a hot junction (placed in the cylinder head) produce a small voltage that changes with temperature. This voltage is read by the indicator and converted into a temperature reading. Why this sensor fits: the environment around the cylinder head is extremely hot and can fluctuate rapidly. Thermocouples tolerate high temperatures, respond quickly to changes, are rugged, and are cost-effective, making them ideal for aviation engines where accurate head-temperature readings are crucial for safe operation. Other sensors measure different quantities. A Bourdon tube responds to pressure, not temperature. Capacitance sensors are used for level or certain dielectric measurements, not reliable direct temperature indication in this harsh engine area. Strain gauges detect deformation, not temperature. Since the goal is a direct, reliable temperature reading from the cylinder head, a thermocouple is the appropriate choice.

Cylinder-head temperature indicators rely on a thermocouple to measure heat directly from the engine head. A thermocouple uses the thermoelectric effect: two dissimilar metals joined at a hot junction (placed in the cylinder head) produce a small voltage that changes with temperature. This voltage is read by the indicator and converted into a temperature reading.

Why this sensor fits: the environment around the cylinder head is extremely hot and can fluctuate rapidly. Thermocouples tolerate high temperatures, respond quickly to changes, are rugged, and are cost-effective, making them ideal for aviation engines where accurate head-temperature readings are crucial for safe operation.

Other sensors measure different quantities. A Bourdon tube responds to pressure, not temperature. Capacitance sensors are used for level or certain dielectric measurements, not reliable direct temperature indication in this harsh engine area. Strain gauges detect deformation, not temperature. Since the goal is a direct, reliable temperature reading from the cylinder head, a thermocouple is the appropriate choice.