Editorial Feature

Exhaust Gas Temperature Gauges

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An exhaust gas temperature (EGT) gauge is a device that measures the temperature of emitted gas from a car internal combustion engine. The measurement of EGT is based on the interaction of factors of combustion such as time length, ignition, fuel, compression and oxygen. Very minute changes in these factors will lead to significant variations in the measurements of EGT.

The temperature of exhaust gas at a stoichiometric air-fuel ratio varies from the temperature at a rich air-fuel ratio. The fuel tends to cool at rich air-fuel ratio, and hence the temperature of exhaust gas decreases.

Working Principle of Exhaust Gas Temperature Gauges

A typical EGT gauge is fabricated using a metal alloy, usually alumel and chromel to protect the sensing components inside. A thermocouple sensor located at the welded junction of metals is used for measuring the temperature of exhaust gas. When both metals are subjected to same amount of heat, they produce differing voltages. These voltage signals are then measured using a voltmeter.

Benefits of Exhaust Gas Temperature Gauges

The key benefits of EGT gauges are given below:

  • Prevention of spark plug fouling
  • Less pitting for fuel
  • Simple and inexpensive
  • Operation at peak EGT
  • Adjusting fuel-to-air ratio for peak efficiency
  • Suitable for any type of internal combustion engine
  • Ensures peak engine performance at high speeds.

Applications of Exhaust Gas Temperature Gauges

The EGT gauges are mainly used for measuring and regulating exhaust gases in the following:

  • Internal combustion engines
  • Compressors
  • Turbines.

Advancements in exhaust gas temperature gauges will involve using sensors and actuators with integrated intelligence and for these instruments to withstand harsh settings without failing under test conditions.

Sources and Further Reading

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