bimetallic thermostats

JB Controls, in close collaboration with Sensata Technologies, offers the most complete range of bimetallic thermostats for industrial, railway, aerospace, military, and space applications. These thermostats, preset for a temperature range from -54°C to +284°C, can be supplied in isolated units or in bulk quantities, with options for clip attachment or printed circuit board mounting. Thus, we will find the ideal product to meet your needs depending on your environment.

Range for your industrial applications

Découvrez les thermostats JB Controls (bannière 3)
thermostat miniature 6700 sur fond bleu

6700 Miniature Thermostats

Factory preset miniature thermostats, 40°C to 130°C, PCB mountable. RoHS compliant, accurate and reliable detection in a small device footprint, fast response, excellent repeatability. Can be placed and soldered onto boards with automated equipment, compliant with Y220/TO220. Airpax® 6700 series.

Thermostat 20425

20425 Thermostats

Sealed thermostat, cut-off >25A, SPST or SPDT. Factory preset Klixon® 20425 series, cost-effective. Sealed design for HVAC applications. Fast and accurate switching due to the snap action of the disc. Available in various mechanical configurations.

5100 Thermostats Probe

Hermetic unipolar and unidirectional thermostat probe, with different terminals and bases, configurable temperatures from 2°C to 249°C. This product range has been specifically designed for applications requiring high tolerance to vibrations. The thermostat probe has its disc located at its very end, ensuring a quick and reliable response.

1NT Thermostats

Pre-set thermostats with automatic or manual reset, ranging from -40° to 240°, reliable and widely used in various industries for temperature control and safety regulation, thanks to its patented quick-action bimetallic disc. We offer the 1NT with a wide range of mounting and configuration options.

Thermostat 1NT

3NT Thermostats

Waterproof pre-set thermostats, -40° to 240°C, with automatic reset. Reliable and widely used for temperature control and regulation, featuring a patented quick-action bimetallic disc. Available with various mounting options. 3NT is based on the proven 1NT thermostat, which has been used in millions of devices.

Thermostat 3NT

5003 Thermostats

Low Profile Thermostats 1/2″, from 0°C to 163°C, various configurations available. The 5003 series includes SPST bimetal disc thermostats. Compliant with RoHS standards. High resistance to shocks and vibrations thanks to its robust design. Sealed for applications in high humidity and contaminated atmosphere. Narrow differentials available for precise control.

Thermostat 5003


Découvrez les thermostats JB Controls (bannière 2)
Thermostats 11041 Series Space

11041 Series Space Thermostats

Embeddable thermostat following G311P641/05. The Klixon® 1041 Series Space thermostats are used for extremely demanding environments such as satellites, launchers, and other manned spacecraft. Before final sealing, each thermostat is filled with an inert gas (nitrogen) to prevent condensation and contamination. Furthermore, this range of thermostats has exceptional resistance to vibrations and shocks.

Thermostats M2 Series Space

M2 Series Space Thermostats

Embarquable thermostats following G311P641/02. Klixon®’s M2 Series Space thermostats are used for extremely demanding environments such as satellites, launchers, and manned spacecraft. These thermostats are available with a very narrow differential and are filled with an inert gas (nitrogen) before final sealing to prevent condensation and contamination. Additionally, this range of thermostats has exceptional resistance to vibration and shock.


Découvrez les thermostats JB Controls (bannière)

7BT Thermostats

Waterproof 1/2″ thermostats, configurable from -1°C to >200°C, NC or NO. Klixon®’s 7BT range thermostats are designed to offer high switching power. They can handle up to 15 Amps at 120 Volts AC and 10 Amps at 30 Volts DC. Designed around a bimetallic disc, it provides a sharp switching action in a product protected from dust and other foreign particles.

Thermostats 7BT

5BT Thermostats

Hermetic 1/2″ SPDT thermostats, per M24236/24. Klixon® 5BT series thermostats are economical and highly reliable bidirectional unipolar thermostats. This configuration allows for dual function within a single device, such as a safety system and a cooling fan. These thermostats are highly resistant to shocks and vibrations and are available in numerous configurations from -54 to 205°C.

Thermostats 5BT
Thermostats 11041 - M1

11041 - M1 Thermostats

Hermetic 1/2″ thermostats following M24236/1, from -54°C to 288°C. These Klixon® M1/11041 thermostats are designed to provide exceptional resistance to vibration and shock to deliver reliable switching for your demanding applications. To avoid any risk of condensation or contamination, these thermostats are filled with an inert gas (nitrogen) before being sealed. In addition, this operation also improves the dielectric characteristics of the Klixon® by preventing oxidation of the contacts.

Thermostats M2

M2 Thermostats

Hermetic low differential thermostats for temperature monitoring applications according to M24236/20. To avoid any risk of condensation or contamination, these Klixon® thermostats are filled with an inert gas (nitrogen) before being sealed. This operation also improves the dielectric characteristics of the Klixon® by preventing contact oxidation. The Klixon® M2 thermostat is the ideal choice when a reliable and narrow differential switching is essential.

4344 Thermostats

Pre-set automatic reset thermostats, hermetic 1/2″, current up to 7A, NC or NO, from -54°C to 288°C, solder terminals, many fixations, available in ‘1 shot’. This Klixon® 4344 series thermostat is based on a bimetallic disc which allows for a sharp switching action. Moreover, this feature ensures a reliable and constant operating temperature over a very large number of cycles.

Thermostats 4344


“Sealed 1” thermostats with high switching capacity (14A/30VDC). The 4391 series thermostats are the most versatile in the Klixon® range. They are available with automatic or manual reset, in unipolar unidirectional or unipolar bidirectional versions. Finally, they are also offered with an overmolding option.

Thermostats 4391
Thermostats 3BT & 4BT

3BT & 4BT Thermostats

Miniature hermetic snap-action thermostats (<1g), with solder or wire terminals, available in screw or glue mount versions, according to M24236/13 & /19. Klixon® 3BT & 4BT series thermostats are the smallest and lightest thermostats ever developed, allowing for extremely fast response time. They are designed to withstand particularly demanding applications in terms of shock and vibration resistance, and are available with a variety of mounting options.

Sondes thermostatiques

Thermostatic probes

Hermetic 1” thermostat with high switching capacity (14A/30VDC), SPST or SPDT, automatic or manual reset.

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What is a Bimetallic Thermostat?

M1 thermostat

A bimetallic thermostat or bilame uses the difference in thermal expansion between two metals to regulate the temperature of a system by opening or closing an electrical circuit. There are several types of bimetallic thermostats, the most common of which is the bimetallic disc thermostat.

In the industrial sector, it is often used as a safety device that functions as a switch. It triggers at a defined temperature, most often set at the factory. This allows the temperature to be regulated, for example by cutting off the power to a heating element in a heating system once the desired temperature is reached.

Sensata Technologies has been developing and marketing thermostats under its Klixon® brand for years. These thermostats operate on the principle of a bimetallic disc, which is made up of two metals with different coefficients of thermal expansion. These discs are stamped to allow for a rapid and decisive change from a concave to a convex shape.

The two metals in the disc react differently to changes in temperature, causing a change in shape from concave to convex and vice versa, thereby either interrupting or ensuring the electrical continuity of a circuit.

logo klixon (JB Controls' partners) fournisseurs industriels

In summary, the bimetallic thermostat is a switch that turns on or off the power supply of a given circuit at a temperature defined by the manufacturer. In industrial settings, bimetallic disc thermostats are often referred to as Klixon® in reference to the American brand that belonged to Texas Instrument, which became Sensata Technologies since 2006. However, there are other manufacturers of bimetallic thermostats that use the same principle of operation with the disc.

How does a Bimetallic Thermostat work?

The operation of a bimetallic thermostat is based on the difference in thermal expansion of the two metals used, for example, brass and stainless steel. These metals have different coefficients of thermal expansion, meaning they react differently to changes in temperature. Additionally, when the temperature increases, one layer of the bimetal expands more than the other, triggering a deformation of the bimetal.

Operating principle, choice of 2 metals:

Operating principle, choice of 2 metals

Diagram illustrating the deformation of the bimetallic strip:

The two metals are joined together, and for the example, let’s consider the deformation caused by a temperature increase from 20 to 100°C.

Diagram of the change in state of the bimetallic disk

The metal 1 having a higher coefficient of thermal expansion than metal 2, the bimetallic strip is then deformed and gives a convex shape to the strip. This deformation is progressive as the temperature increases. The change of state is slow and not instantaneous. That type of bimetallic strip cannot be used as a safety device.

Here is where the bimetallic disc comes in, which is stamped to give it a concave/convex shape at room temperature. This operation allows for a quick and immediate change of state at a given temperature.

How does a Bimetal Disc Thermostat work?

The bimetallic disc thermostat is therefore a stamped bimetallic disc to obtain a bimetallic disc whose change of state from concave to convex is instantaneous.

Diagram of the quick-action change of state of a bimetallic disc :

Schematic representation of the change in state of the bimetallic disk

The bimetallic disc thermostat is thus a stamped bimetallic disc in which the change in state from concave to convex is instantaneous. This allows the thermostat to be used as a reliable safety element in a multitude of industrial applications. The change in state of the bimetallic disc that triggers the thermostat is called “instantaneous action”, meaning that the switch is quick and definite. Additionally, for specific applications, the majority of bimetallic thermostats are pre-set at the factory, with manufacturing being done based on the specific needs of the application.

The bimetallic disc can return to its initial state in one of two ways:

  • Automatically, at a defined temperature when it cools down, which is known as an “automatic reset” thermostat.
  • Manually, where an operator presses a button to reset the disc to its original state, which is called a “manual reset” thermostat.

General schematics of the Klixon® type bimetallic disc thermostat:

close scheme
open scheme

The tilting of the bimetallic disc causes the movement of the ceramic plunger which in turn causes electrical contact between the two terminals of the thermostat. It is now closed, and current flows between the two terminals.

A large number of parameters are taken into account in the definition of Klixon® thermostats, including :

  • Initial state of the thermostat: Normally Open (NO) or Normally Closed (NC)
  • Trigger temperature and its tolerance, for example: 49°C +/-3°C
  • Differential: the temperature at which the thermostat returns to its initial state in the case of an automatic reset Klixon®
  • Numerous other factors such as the electrical power to be cut off, vibrational environment, shock resistance, mechanical configuration (fixation), are taken into account.

What are the common applications of a bimetallic thermostat?

Due to their role as safety and regulation devices, Klixon® thermostats are ubiquitous in individual and collective households, businesses, and a large number of industries:

  • Home appliances : Thermostats are incorporated in refrigerators, freezers, ovens, microwaves, dryers, and coffee makers to ensure a stable temperature.
  • Heating and cooling : Thermostats are a key component in heating and cooling systems for homes and commercial buildings, as well as for refrigerated transport in the HVAC field.
  • Industrial equipment : Bimetallic thermostats are used in industrial equipment such as electric motors, transformers, pumps, electronic cards, etc.
  • Laboratory equipment : Many thermostats are used in laboratory equipment and in the medical field to protect costly analysis, diagnostic, and patient monitoring tools.
  • Vehicles : Bimetallic thermostats ensure proper operation of vehicle engines by detecting any abnormalities in engine oil and coolant temperature. They are also used to monitor the batteries of electric vehicles and prevent any risk of fire.

In conclusion : From a few Euro kettle to multi-million Euro satellites and launchers, bimetallic thermostats ensure the safety of systems ranging from the simplest to the most complex.

What are the advantages of a bimetallic thermostat?

The advantages of bimetallic thermostats are numerous, we will list below the main points:

  • Speed : The Klixon® disk changes state suddenly and sharply, ensuring its proper switching function. The thermostat is either open or closed, there is no in-between.
  • Cost : Bimetallic thermostats are cheaper than electronic thermostats and are much more reliable because they rely on mechanical operation.
  • Reliability and accuracy : Bimetallic thermostats are simple mechanical devices that do not require energy to operate, so they are very reliable and less prone to failures. Thus, each thermostat is configured to last a minimum number of cycles. This number of cycles also depends on the electrical power to be cut.
  • Pre-calibrated : There are adjustable bimetallic thermostats (often with a screw) or factory pre-calibrated. The latter often offers the advantage of being protected against the environment (dust, water, oil, etc.). In addition, pre-calibrated bimetallic thermostats are more accurate and reliable over time.
  • Adaptability : The Klixon® is available in a multitude of sizes and finishes, as well as with a wide range of fixings, whether to stick, fix, clip, etc. We find it on electronic cards as well as on heavy-duty pumps and motors installations.

What are the main applications of bimetallic thermostats?

As seen previously, bimetal thermostats are present in most electronic devices that can overheat or require temperature regulation. We will list, in a non-exhaustive way, the following markets:

      • Household appliances
      • Industrial
      • Military
      • Space
      • Railway
      • Aerospace
      • Energy
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