Capillary Thermostats
A capillary (gas-filled) thermostat transmits the expansion of a liquid or gas-filled bulb through a capillary tube to a bellows, changing an electrical contact at the set temperature.
It is used for temperature control on boilers, ovens, dryers, water heaters and process equipment. The product range includes single and double contact models with 1–2 m capillaries in ranges such as 0/40, 0/90, 40/120, 0/300 and 0/310 °C.
Main Applications
- Boiler and water heater control
- Oven and dryer temperature
- Process tank heating
- Thermal oil systems
- In-panel device control
- Greenhouse and incubator heating
Technical Data
| Operating principle | Liquid expansion sensor (bulb and capillary) |
|---|---|
| Setting ranges | 0/40, 0/90, 0/120, 0/300, 64/210 °C and −30/+34.5 °C (parent group sheet); 40/120, 0/310 °C (product names) |
| Contact | Single pole double throw (SPDT); double contact types available |
| Capillary length | 1000 mm; 2 m capillary type available |
| Bulb | Depending on model |
| Contact rating | Depending on model |
| Protection class | Depending on model |
| Mounting | Panel or device housing |
Material Options
| Part | Single contact | Double contact |
|---|---|---|
| Contact | SPDT | Two-stage SPDT |
| Typical use | On-off heating | Two-stage heating / alarm |
| Setting | One set point | Two set points |
| Capillary | 1 – 2 m | 1 – 2 m |
Which material? The capillary must not be crushed or bent to a radius below 10 mm; the bulb must be fully immersed at the measuring point. Setting ranges come from the manufacturer sheet and product names.
Advantages
Wide Setting Range
- From −30 to 310 °C
Remote Sensing
- Via capillary
Double Contact Option
- Two-stage control
Needs No Power
- Mechanical sensing
Construction and Design Features
- Liquid-filled bulb
- Capillary tube
- Bellows and contact mechanism
- Setting knob
Send the setting range, capillary length, contact count and mounting place; we will confirm a suitable capillary thermostat from stock.
How to Choose?
- Mounting and capillaryFind where the device sits and how much capillary it needs.
- Bulb placementCheck pocket or clamp needs for the bulb.
- Setting rangeChoose a range covering working temperature.
- ContactChoose single or double contact type.
Complementary Products
Why ORFA?
Other Thermostats
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Frost protection thermostats protect air and water coils from freezing by reacting when temperature falls.
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Boiler Thermostats
Boiler thermostats control the burner or pump to keep boiler water at the set temperature.
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Incubator Thermostats
Incubator thermostats keep the temperature in incubators steady and precise.
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Surface Thermostats
Surface thermostats sense temperature through contact with a pipe or surface and switch a contact.
Details →Get a quote for your project
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