What advantages do pressure switches with metal bellows offer and what is the foundation for these? The advantages derive from the seamless design of their measuring system. This solution enables permanently stable repeatability and, as well, eliminates the chance of leakage.
Controversial measuring systems derive from a mature manufacturing technology. The production of metal bellows, for instance from stainless steel or perhaps a copper alloy, takes place in a number of steps. Circular discs are first cut from the flat little bit of metal, and they are then shaped into cup-shaped objects. They are softened via an annealing process in a furnace at more than 600 �C and drawn into long, thin-walled and seamless tubes.
Constant elasticity
The tubes are corrugated by using forming tools at high pressure, and are trimmed to the designed size. Within the next stage, the spring-like metal cylinders are pressed together in accordance with the specified dimensions (length, outer and inner diameter). This creates the constant elasticity needed for the stable repeatability of the movement. In the final step, the bellows are degreased and passivated, i.e. given a protective coating against corrosion.
Bellows manufactured from stainless for pressure switches
Seal-free functionality
In a pressure switch, the metal bellows is brazed or welded to the procedure connection. Its other end is in contact with the transmission mechanism. Because of this the instrument has a fully seamless measuring system with no need for just about any rubber sealing materials and the chance of leakage is eliminated. This feature makes pressure switches with metal bellows ideal for a wide range of applications. Process reliability is also guaranteed with liquid media.
Permanent accuracy
A metal bellows changes its length based on the pressure. Whenever a defined switch point is reached, it triggers the switching function with a transmission mechanism. If the pressure drops or rises again, the bellows returns to its original shape and the switch contact returns to its original position.
The expansion movement of a metal bellows includes a high linearity. The switch differential, that is precisely adjusted via a specific calibrated spring system, remains correspondingly constant. This ensures the accuracy of pressure control and switching, even over a long period of time.
Note
Detailed info on pressure switches with metal bellows, e.g. models PSM-520, PSM-550 and PSM-700, are available on the WIKA website. You want to buy pressure switches with metal bellows? In our WIKA online-shop you will find a few of our standard designs. For those who have any questions, your contact will gladly assist you to.