Pressure switches with metal bellows: Stable repeatability, no threat of leakage

What advantages do pressure switches with metal bellows offer and what is the basis for these? The advantages are based on the seamless design of these measuring system. This solution enables permanently stable repeatability and, at the same time, eliminates the chance of leakage.
Bellows measuring systems are based on a mature manufacturing technology. pressure gauge octa of metal bellows, for example from stainless steel or a copper alloy, occurs in several steps. Circular discs are first cut from the flat piece of metal, and these are then shaped into cup-shaped objects. They’re softened through an annealing process in a furnace at a lot more than 600 �C and then 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 ultimate step, the bellows are degreased and passivated, i.e. given a protective coating against corrosion.
Bellows manufactured from stainless steel for pressure switches
Seal-free functionality
In a pressure switch, the metal bellows is brazed or welded to the process connection. Its other end is in contact with the transmission mechanism. Therefore 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 via 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, which is precisely adjusted with 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, can be found on the WIKA website. You want to buy pressure switches with metal bellows? Inside our WIKA online-shop you will find some of our standard designs. When you have any questions, your contact will gladly assist you to.

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