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Tag Archives: Mineral Insulated

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

Original Equipment Temperature Sensors

Many equipment designers require temperature measurement inputs in Original Equipment they are creating. Demands for thermal control, overheat protection, temperature compensation, heater and cooler switching all require system signals.

 

Working with Original Equipment Designers.

 

Peak Sensor staff are never happier than when we are talking to a design engineer about a new application. Engineers know their product well. Peak Sensors staff know about sensors. Put the two together and great solutions can emerge.

 

Good sensor design identifies the balance between a number of conflicting parameters

 

  • Probe Cost
  • System cost
  • Robustness
  • Protection from ambient conditions
  • Speed of response
  • Process connection
  • Accuracy
  • Sensor lifetime
  • Subsequent assembly
  • Replacement

 

Peak Sensors has a long history of working with designers to create optimal solutions for original equipment.… 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

Temperature Sensor Radiation Error in an Aerospace Furnace

Measurement errors can be undetected and highly significant. I had a great example of sensor radiation error recently.

I took a telephone call from a customer telling me my temperature sensors were inaccurate. He was building an AMS 2750D compliant Aerospace Furnace. He bought a number of thermocouples from Peak Sensors which were all UKAS calibrated.

System Design

There was a combination of Mineral Insulated Type N and Ceramic Insulated Type R (wire Ø 0.25mm) sensors. In four locations, a type N and a type R were installed adjacent to each other. One would expect them to read very similar temperatures. During pre commissioning trials it was noticed that at times there was up to 50°C difference between the pair.… Read more