From RS Pro a range of Type J thermocouple temperature sensors that conform to IEC 60584 standards. These Type J thermocouples have a durable design with glass fibre insulated wires surrounded by a stainless steel braid and a probe enclosed in a rugged 316 stainless sheath. The end of the probe is fitted with a spring loaded latch mounting 2 slot bayonet connector. This connector allows the thermocouple to be fitted securely. The grounded hot junction of this thermocouple allows it to have a fast response time

A thermocouple is a sensor used to measure temperature in a range of different processes and consists of two wire legs made from different metals joined together at their two ends to form two junctions. The hot, or measuring junction is connected to the body whose temperature is going to be measured. The cold junction or reference junction is connected to a body of known temperature. When the measuring junction is placed on something hot a voltage or potential difference between this and the reference junction occurs. This voltage can then be converted into a temperature measurement using thermocouple reference tables. This process is also known as the Seebeck Effect

In a welded grounded junction the two thermocouple wires and sheath are welded together to form one junction at the probe tip. These thermocouples have a fast response time because all the thermocouple is making contact with the sheath allowing the heat to transfer easily.

The probes of these thermocouple sensors have an adjustable compression spring 250 mm long with a 2 slot bayonet fixing cap. The bayonet cap screws along this spring and allows the immersion length of the thermocouple probe to be adjusted. Once in place the bayonet cap is secured into the equipment and firmly held in place. The advantages of this method of fixing are;

• Immersion depth can be adjusted easily
• Secure connection within machine recess
• Positive pressure at the thermocouple tip and full immersion in process

• Adjustable bayonet probe
• Rugged 316 stainless steel sheath for resistance to corrosion
• Grounded hot junction
• Fast response time
• Robust glass fibre stainless steel overbraid wire

These Type J adjustable bayonet probe thermocouples are designed for direct installation into the process. The bayonet fitting makes them suited for applications where the thermocouple sensor tip is fitted directly into a drilled hole or recess in machinery. Typical applications include temperature measurement in the plastics and rubber industry where they are used in extrusion and moulding machinery