NTC Thermistors
Vishay
FEATURES
• Custom Designed using CAD to Individual Requirements
• Wide Range of Materials and Mounting Styles
• Typical Applications Include Automotive, Refrigeration, Air-conditioning and Industrial Controls.
TYPICAL ASSEMBLY STYLES AND APPLICATIONS
Standard and custom assemblies are available in a variety of configurations. The choice of assembly style is dependent on the
application. The primary factors which determine the optimum configuration of a thermistor assembly are the operating
environment, mounting, time response and minimum dissipation constant.
The two factors which do vary considerably with assembly design are time constant and dissipation constant. The time constant will
typically be of greater duration in encapsulated thermistors. This is, of course, due to additional mass surrounding the thermistor
element; therefore, extending the thermal transfer time. Dissipation constant will also be greater in assemblies. The additional
housing mass serves well as a heat sink. Greater power is therefore required to induce self-heating.
Both time constant and dissipation constant will vary with the selected thermistor and housing. Heat transfer properties of the
housing, thermistor location, mass and wire type determine these constants. It is recommended to evaluate or consult the factory in
applications where T.C. and D.C. are critical.
• IMMERSION PROBES
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1. Thread Mounted:
Features a stainless steel tube with a hermetically sealed threaded hex fitting.
Available in 1/8", 3/16" and 1/4" outer diameter tubes with 1/8" or 1/4" NPT hex fittings. Ideal for
pressured, closed systems.
2. Penetration Probe:
7" long x 1/8" outer diameter stainless steel tube. Pointed tip easily
penetrates soft and semi-frozen materials. Also ideal for soil and ground measurements.
3. Tubular Stainless Steel:
1/8", 3/16" and 1/4" outer diameter tubes in variable lengths. Good for
universal immersion applications. Adaptable to use with compression thread mounts to give
designer variable immersion depths.
4. Tubular Pyrex®:
6" long x 3/16" outer diameter glass tube. Excellent for lab use where a
chemically inert probe is required.
5. Flexible Immersion:
1.5" long x .280" outer diameter aluminum housing. Flexible 105°C PVC
tubing to protect wire and thermistor element from the liquid medium. Ideal assembly for
intermittent immersion in hard to reach areas.
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• GENERAL PURPOSE SENSORS
11. Delrin® Housing:
1/2" long x .170" outer diameter thermoplastic. Excellent for environmental
controls and applications below 100°C.
12. Stainless Steel Rod:
.875" x .156" outer diameter. Good for environmental chamber
measurement where corrosive gasses exist.
13. Gold Anodized Flanged Sensor:
.630" long x .275" outer diameter with a .298" flange
diameter. An easy to mount press fitting.
14. ABS Housing:
.476" long x .230" outer diameter. Black thermoplastic and configuration suits it
well in air flow temperature measurements.
15. Polyester Housing:
1.50" long x .280" outer diameter. Heavy thermoplastic case makes it ideal
for applications requiring delayed time responses. Ideal for process controls in refrigeration and
heating.
16. Epoxy Tip Probe:
Durable epoxy encapsulation, small size, fast time response, versatility and
low cost make this sensor universally accepted. Assembly size will vary with wire and thermistor
choice.
17. Pipe Sensor:
.625" long with a cut-out radius of .250" suits this nylon thermoplastic as an ideal
pipe sensor. Extensive use is seen in environmental and water heating/cooling systems.
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• SURFACE SENSORS
21. Ring Tongue Lugs:
Surface mount with a #4, #6, #8 or #10 screw. Excellent for measurement
and control of surfaces where fast time responses are necessary.
22. Heat Sink Sensors:
Available in brass, aluminum or stainless steel with various threads. A
durable and practical surface sensor, especially where shock and vibration are present.
23. Rectangular Block Sensors:
Aluminum blocks for measurement and control of large surface
areas. Easily mountable with #6 screws.
www.vishay.com
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Document Number: 10022
Revision: 05-Sep-03
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