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Thermostat
Klixon 3BT and 4BT Series
 
 
 
 
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Common Applications of 3BT and 4BT Precision Thermostats
The Tiny Stat thermostats afford the user the quality and performance of a Klixon thermostat in a sub–miniature package. Tiny Stats are the smallest snap–acting thermal switches ever made, which makes them the ideal choice in applications where size and weight are critical. This small envelope design translates to a low thermal mass which yields one more key feature, an extremely fast thermal response.

Tiny Stats are commonly used for...
- Electronics Overheat Protection
3BT-15 and 4BT-15 configurations are printed circuit board mountable. Other configurations can be epoxied in place.
- Transformer Windings
The low–profile design of the 4BT-2 is optimal
- Medical Equipment
Where rapid thermal response is critical

Site Updated September 19, 2017

* * * Sensata > Products > Klixon Brand > Thermostats > Precision Thermostats >

Klixon® 3BT and 4BT Series Thermostats
0°F to 350°F, Tiny Stat Precision Thermostats


Smallest snap–acting thermal switches ever made
Extremely fast response
Single pole, single throw (SPST)
Normally open or closed
Preset, non-adjustable calibration
Hermetically sealed and back–filled with nitrogen
Gold plated
Various mounting configurations available
Qualified to MIL-PRF-24236/13 (4BT) and MIL-PRF-24236/19 (3BT)
Qualified to NASA S-311-641/06 (4BT) and NASA S-311-641/07 (3BT)

Klixon Tiny Stats combine an impressive list of superlatives in a reliable, hermetically sealed, snap–acting Klixon design. They are the smallest envelope size ever developed — ideal for remote sensing applications in locations with severe space limitations. They are the lightest construction available — perfect for applications where weight is an important consideration. They have an extremely fast response in order to permit early warning of overheat conditions. The low mass internal components allow Tiny Stat precision thermostats to meet the most demanding shock and vibration standards of MIL-PRF-24236.

For more information, see the page of free drawings available for download.

Performance

Gold plated contacts can be furnished to assure reliable circuit switching under low wattage conditions. (See second table below.) Gold plated contacts are not suitable for higher loads.

Contact Ratings (Resistive) Based on standard differential
115 VAC/30 VDC
30 mVAC*
30 mVDC*
Life Cycles
1.0 Amp
0.01 Amp
0.01 Amp
10,000 cycles
* Specify gold contacts.

Gold Contact Ratings (Resistive)
30 VAC/DC
500 mA and below
115 VAC
200 mA and below

Characteristics
Switch Action
SPST (snap–action)
Contact Resistance
0.050 ohms maximum (0.100 ohms maximum for close on rise devices with setpoints greater than 175°F) per MIL-STD-202, Method 307
Dielectric Strength
500 vac, RMS, 60 Hz for 5 seconds, across open contacts, per MIL-STD-202, Method 301
Vibration Resistance
5–2000 Hz, 30 G, per MIL-STD-202, Method 204
Vibration resistance specification does not apply to devices that open on temperature rise while at temperatures of 75°F or more below the opening temperature or to devices that close on temperature rise while at temperatures of 75°F or more above the closing temperature.
Shock Resistance
100 G, 6 milliseconds per MIL-STD-202, Method 213
Hermeticity
1 x 10-8 atm cc/sec. maximum, per MIL-STD-202, Method 112, Condition C
Salt Spray Resistance
Per MIL-STD-202, Method 101, Condition B, 5% solution
Weight
Basic Unit: 0.2 to 0.9 grams
Ambient Temperature Range
-80°F to 350°F (-62.2°C to 176.7°C)

Dash
Operating
Temperature
Differential
Tolerance
#
°F
°C
°F
°C
±°F
±°C
1
0
-17.8
30
16.7
8
4.4
2
5
-15.0
30
16.7
8
4.4
3
10
-12.2
30
16.7
8
4.4
4
15
-9.4
30
16.7
8
4.4
5
20
-6.7
30
16.7
8
4.4
6
25
-3.9
30
16.7
8
4.4
7
30
-1.1
30
16.7
8
4.4
8
35
1.7
30
16.7
8
4.4
Dash
Operat. Temp.
Differential
Tolerance
#
°F
°C
°F
°C
±°F
±°C
9
40
4.4
30
16.7
8
4.4
10
45
7.2
30
16.7
8
4.4
11
50
10.0
30
16.7
8
4.4
12
55
12.8
30
16.7
8
4.4
13
60
15.6
30
16.7
8
4.4
14
65
18.3
30
16.7
8
4.4
15
70
21.1
30
16.7
8
4.4
16
75
23.9
30
16.7
8
4.4
Dash
Operat. Temp.
Differential
Tolerance
#
°F
°C
°F
°C
±°F
±°C
17
80
26.7
30
16.7
8
4.4
18
85
29.4
30
16.7
8
4.4
19
90
32.2
30
16.7
8
4.4
20
95
35.0
30
16.7
8
4.4
21
100
37.8
30
16.7
8
4.4
22
105
40.6
30
16.7
8
4.4
23
110
43.3
30
16.7
8
4.4
24
115
46.1
30
16.7
8
4.4
Dash
Operat. Temp.
Differential
Tolerance
#
°F
°C
°F
°C
±°F
±°C
25
120
48.9
30
16.7
8
4.4
26
125
51.7
30
16.7
8
4.4
27
130
54.4
30
16.7
8
4.4
28
135
57.2
30
16.7
8
4.4
29
140
60.0
30
16.7
8
4.4
30
145
62.8
30
16.7
8
4.4
31
150
65.6
30
16.7
8
4.4
32
155
68.3
30
16.7
8
4.4
Dash
Operat. Temp.
Differential
Tolerance
#
°F
°C
°F
°C
±°F
±°C
33
160
71.1
30
16.7
8
4.4
34
165
73.9
30
16.7
8
4.4
35
170
76.7
30
16.7
8
4.4
36
175
79.4
30
16.7
8
4.4
37
180
82.2
30
16.7
8
4.4
38
185
85.0
30
16.7
8
4.4
39
190
87.8
30
16.7
8
4.4
40
195
90.6
30
16.7
8
4.4
Dash
Operat. Temp.
Differential
Tolerance
#
°F
°C
°F
°C
±°F
±°C
41
200
93.3
30
16.7
8
4.4
42
205
96.1
30
16.7
8
4.4
43
210
98.9
30
16.7
8
4.4
44
215
101.7
30
16.7
8
4.4
45
220
104.4
30
16.7
8
4.4
46
225
107.2
30
16.7
8
4.4
47
230
110.0
30
16.7
8
4.4
48
235
112.8
30
16.7
8
4.4
Dash
Operat. Temp.
Differential
Tolerance
#
°F
°C
°F
°C
±°F
±°C
49
240
115.6
30
16.7
8
4.4
50
245
118.3
30
16.7
8
4.4
51
250
121.1
30
16.7
8
4.4
52
255
123.9
30
16.7
8
4.4
53
260
126.7
30
16.7
8
4.4
54
265
129.4
30
16.7
8
4.4
55
270
132.2
30
16.7
8
4.4
56
275
135.0
30
16.7
8
4.4
Dash
Operat. Temp.
Differential
Tolerance
#
°F
°C
°F
°C
±°F
±°C
57
280
137.8
30
16.7
8
4.4
58
285
140.6
30
16.7
8
4.4
59
290
143.3
30
16.7
8
4.4
60
295
146.1
30
16.7
8
4.4
61
300
148.9
30
16.7
8
4.4
62
305
151.7
30
16.7
8
4.4
63
310
154.4
30
16.7
8
4.4
64
315
157.2
30
16.7
8
4.4
Dash
Operat. Temp.
Differential
Tolerance
#
°F
°C
°F
°C
±°F
±°C
65
320
160.0
30
16.7
8
4.4
66
325
162.8
30
16.7
8
4.4
67
330
165.6
30
16.7
8
4.4
68
335
168.3
30
16.7
8
4.4
69
340
171.1
30
16.7
8
4.4
70
345
173.9
30
16.7
8
4.4
71
350
176.7
30
16.7
8
4.4
Consult Sensata Technologies if desired operating temperature does not appear on table.

Configurations

Configuration Options - Custom configurations are available
Pin–Type Terminals
for quick assembly to printed circuit boards (3BT-2 and 3BT-15)
Threaded Plug
For surface temperature sensing (3BT-3)
Insulated Version
For applications where grounded case construction is not suitable (3BT-6)
Low Profile
For applications where an extremely low profile is critical (4BT-2)
Other
Other styles are available

For more information, see the page of free drawings available for download, contact us, contact a distributor, or make an online request for additional information.

Our most common configurations are shown below, but other styles are available:

* * *
Klixon
Miniature Thermostats

Miniature Thermostats

Qualifications

Military Specifications:
  • 3BT: MIL-PRF-24236/19
  • 4BT: MIL-PRF-24236/13

  • NASA Specifications:
  • 3BT: S-311-641/07
  • 4BT: S-311-641/06

  • Drawing

    Part Numbering System

    A breakdown of our part numbering system for standard 3BT and 4BT thermostats is shown below. You may need to contact Sensata Technologies for the style code.

    Drawing

    The World Depends on Sensors and Controls