Tip styles & Junction Types
Thermocouple Tip styles
round Tip is the standard tip provided unless other wise specied. It can be used in an open atmosphere, in a thermowell, in a liquid or air, and high pressures .
flat Tip reduces the amount of“sheath”material at the tip of the probe, which can potentially aect the response time, less mass for thermal conduction into the thermocouple junction.
drill point Tip (118 deg tip) allows more of the tip surface to be in direct contact with the surface area of a hole, which normally has been “drilled” to the depth required, as opposed to being milled at at the bottom.
needle Tip is shaped to a ne point similar to a sewing needle. This facilitates the sensor tip to be inserted into an object for temperature measurement such as food processing, monitoring “skin” temperature on automobile tires at a test track. Not available in diam- eters below 1/16”.
reduced Tip sensor for 1/8” reduced to 1/16”(reduced section is 3/8” to 1.0”) al- lows the “ruggedness” of the 1/8” diameter while giving the fast response of a 1/16” diameter probe. Alternative to a swaged reduced tip is a “step down” version of the reduced tip. This is facilitated by brazing or welding (depends on the diameter) a smaller diameter “MgO” thermocouple inside a larger diameter tube. This again allows the support or ruggedness of the larger diameter while maintaining the fast response of a smaller diameter sensor.
Junction Tip Style
118° drill Tip
exposed Tip is recommended where fast response is desired, and corrosive conditions are nonexistent. Commonly used in air and gas applications. The thermocouple wires are butt welded together and the insulation sealed against liquid or gas penetration into the magnesium oxide insulation. The normal exposed length is equal to 1½ times the diameter of the probe, it is not available in 0.010” diameter.
vented Tip is an exposed junction tip design were the senor is protected by a laser cut vented shield. Most commonly used on RTD’s where fast response is desired in air and gas to protect the delicate element. It can also be used on Rigid Tube design thermocouples where the wire needs to be exposed and protected.
diagram JT JuncTion TYpes
grounded Junction the wires are welded securely into the closure end of the sheath, becoming an integral part of the junction. The response time is closest to the exposed type junction. Recommended in the presence of liquids, moisture, gas, or high pressures. The wire is adequately protected from corrosive or erosive conditions. Not recom- mended in 0.500” O.D.
ungrounded Junction the thermocouple junction is fully insulated from the welded sheath end. The response time is longer, than a grounded junction. It is excellent for electrical applications where stray emf’s would aect the reading, gives good noise isolation. It also is useful in applications where rapid or frequent temperature cycling occurs, and provides for longer service life of the sensor.
separate ungrounded junction is only available for a duplex (or triplex) style MgO material. It gives your application the usefulness of two (three for triplex) separate junctions isolated from each other and the sheath, inside one protective sheath material. Oers the same benets as the ungrounded junction of response time, junction isolation, allowing you to send a signal to a dierent location or for redundancy as a back up.
common ungrounded junction is only available in duplex (or triplex) style MgO material. This is supplied with all the wires welded together separate from the sheath; the junc- tion is isolated from the sheath but no isolation between the junctions. Oers similar benets, response time, etc., as the separate ungrounded with out the junction to junction isolation.
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