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Trend and Wika Thermowells
Wika manufactures both Wika and Trend labeled line of thermometers
as well as a complete selection of accessories.
Thermowells for temperature instruments are recommended for all process systems where pressure,
velocity or viscous, abrasive and corrosive materials are present
individually or in combination. A properly selected thermowell
will protect the temperature instrument from possible damage
resulting from these process variables. Furthermore, a
thermowell permits removal of the temperature instrument for
replacement, repair or testing without effecting the process media
or the system.
Thermowells come in a variety of styles depending on the use. The most common ones are the: threaded, flanges and sanitary. For high pressure and temperature there are also: Socket, Wels and Weld-in types.
Threaded Thermowells
Flanged
Sanitary
Standard Features
- Process Connections: Threaded, flanged, sanitary, socket, weld, weld-in
- Instrument Connection: ½" NPSM standard (National Pipe Standard Mechanical; A straight pipe thread for mechanical joints)
- Shank Configurations: Reduced, straight, tapered
- Bore Diameter: .260", .385"
- Materials: Brass, AISI 304, AISI 316
- Surface Finish: Brass: 60-100 Ra; AISI 304 & AISI 316: 60-100 Ra sanitary (AISI 304 & AISI 316): 16-20 Ra
Thermowell Terminology
- Process Connection:
- External means to connect thermowell to process piping system. Wells can be threaded, bolted (to matching flange), clamped or welded in place.
- Instrument Connection:
- Internal threads to connect temperature instrument to thermowell.
- "U" Dimension:
- Length of well inserted into the piping system. Measured from the base of the process connection to the end tip of well.
- "T" Dimension:
- Also called lagging extension. Extends length between the instrument and process connections to accommodate vessel or piping insulation. Standard length is 3" (2" for a well with a 2½" "U" dimension).
- "S" Dimension:
- Instrument insertion length into well.
- Bore Diameter:
- Dimension of internal bore to match the diameter of the instrument stem/bulb inserted into the well. The .260" and .385" bore sizes fit instrument stem/bulb diameters of ¼" and 3/8" respectively. Bore length equals "S" dimension.
- Root Diameter:
- Diameter of well shank below process connection. This dimension varies with process connection and/or shank design.
- Tip Diameter:
- Diameter of well shank at the end tip of well. This dimension may vary with process connection and/or shank design.
- Reduced Shank:
- Also called reduced tip. The shank O.D. is reduced over the last 2½" of the "U" dimension from the standard root diameter to a ½" O.D. The stepped shank is available with a .260" bore size only.
- Straight Shank:
- Shank O.D. is the same from the root diameter to the tip diameter. The straight shank is generally used with a .385" bore size but a .260" bore size is available.
- Tapered Shank:
- Shank O.D. is gradually reduced from the root diameter to the tip diameter. Available with a .260" or .385" bore size. The tapered shank is recommended for heavy duty applications characterized by high vibration, pressure, temperature and/or velocity.
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