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Tag Archives: mims

Temperature Measurement by Exhaust Thermocouple in Engines

Exhaust Thermocouple Sensors are a key element of modern engine management. Measuring the temperature of exhaust gas can provide an important input into system algorithms to improve efficiency, reduce pollutants and extend engine life.

Exhaust Gas sensors are usually thermocouples due to the very high temperatures involved. Often 800°C or more can be achieved. Thermocouple type K is the most common although type J is also found in lower performance engines.

Exhaust Thermocouple Design

The Primary requirement of an Exhaust Thermocouple is to be robust enough to survive a high vibration environment. After that it must be small enough to respond quickly and not disrupt gas flows.… Read more

Aerospace Heat Treatment Thermocouples to AMS 2750D

Aerospace Heat Treatment applications require AMS 2750D thermocouples. The key point of this standard, for sensor makers, demands that Thermocouples are calibrated by approved means and shown to be within defined limits. Individual sensors or batches of Thermocouple material can be tested. The maximum acceptable error depends on sensor use. There are strict limits on the number of uses before recalibration or replacement is required.

 

Peak Sensors often supplies Mineral Insulated Thermocouples, Rare Metal Thermocouples or Thermocouple wire batch certified. Thermocouple type R, type S and type N are the most common aerospace sensors.

 

Cost Reduction for AMS 2750D

 

To minimise Mineral Insulated Thermocouple sensor costs, Peak Sensors will have batches of wire calibrated and then from it, build sensors according to a customers requirement.… Read more

Mineral Insulated Thermocouples

Mineral Insulated Thermocouples are very common form of temperature sensor. It surprises me how often design engineers are not familiar with the product. They may be called Metal clad, MIMS, pyro or simply MI. Mineral Insulated Thermocouples are covered by IEC 1515:1996.

 

Basic design of Mineral Insulated Sensors

 

The basic Mineral Insulated Thermocouple design has sensor conductors inside a metal tube. Insulation is provided by tightly packed Magnesium Oxide powder. The assembly is robust and ductile. Smaller diameters can be easily bent by hand allowing fairly simple installation through very difficult routes. Diameter 6.0mm and above are more difficult to bend, but can still be routed as required.… Read more

My Sensor Assembly is not as accurate as I was expecting. Why is that?

Temperature sensors have defined accuracy. Thermocouples according to BS EN 60584.2:1993 and Resistance Thermometers to BS EN 60751:1996. Parties involved in accuracy include Calibration Laboratories, Element manufacturers making high volumes of standard sensing elements and Sensor makers who take the primary elements and fabricate a sensor assembly according to user design requirements. In use a sensor can then be in a poor location, or simply be an inadequate design.

Calibration labs

All calibrations have uncertainty ranges. Individual calibrations at laboratories can cost £ 200 or more each. With that a high quality lab does multiple readings in highly controlled conditions.… Read more