Capillary thermostat
Electromecanical control thermostats with capillary bulb
Rathgebers’s capillary bulb thermostats are used all over the world to control and limit temperatures in the range from -30°C to +400°C.
Rathgeber’s products are manufactured professionally in accordance with latest technology and in compliance with the appropriate standard DIN EN 60730, have VDE- and CE-Mark and comply to RoHS.
They operate safely and reliably, provided that specification required is clear at the start of the project.
Rathgeber supply…
… temperature controls, limiters and thermal cut-out with phial and capillary tube length according to customer specification for applications such as:
Boilers – Night storage heaters – Heat exchangers – Water heaters – Laboratory equipment – Ovens of domestic cookers – ashing machines – Dishwashers – Deep fat fryers – High pressure jet washers
Principle of operation
The pressurised system which operates according to the principle of expansion of liquid is the heart of a hydraulic thermostat.
It comprises phial, capillary tube and diaphragm.
Following an increase in temperature at the phial, the liquid expands in the capillary tube, causing the diaphragm to move. This movement activates a snap-action switch, causing opening or closing of switch contacts.
It is clear that a high degree of precision is required in manufacture, as a change in temperature of 1 K can cause a movement of the diaphragm between 0,002mm – 0,01mm.
Single-phase temperature-regulator / -guard certified acc. 
