What type of instrument system is used for measuring cylinder-head temperature and exhaust gas temperature?

• A. A thermocouple system
• B. An RTD-based system
• C. A pressure gauge
• D. A digital thermometer

Answer: (A)

Sensors used for cylinder-head and exhaust gas temperatures must endure very high heat and respond quickly. Thermocouple systems fit this need because a thermocouple produces a small voltage directly from the temperature at its sensing junction, giving fast, real-time readings across the wide temperature range these locations reach. Type K thermocouples are common in these applications due to their broad temperature range and ruggedness, making them ideal for engine environments. RTD-based systems, while accurate, don’t handle the extreme temps as well and typically have slower response in this context, which isn’t ideal for monitoring EGT and CHT. A pressure gauge isn’t relevant to temperature measurement, and a digital thermometer alone isn’t a complete sensor setup for these harsh locations. So, the thermocouple system is the standard choice for measuring cylinder-head and exhaust gas temperatures.