Mechanical pressure switches in compact design ensure safe pressure monitoring in, for instance, pumps, compressors and mobile working machines. Whatever the application, they function in accordance with the principle of the preloaded spring, with a diaphragm or perhaps a piston as the measuring element.
Mechanical pressure switches such as the PSM01 (see illustration) are constructed in accordance with the schematic diagram (left): electrical connection (1), adjustment screw (2), preloaded spring (3), switch contact (4), measuring element (5) and process connection (6). The model PSM01 and model PSM02 (with adjustable hysteresis) are compact switches. They will have a height of 50 mm (version with blade terminal) and spanner widths of 24 and 27.
With Portfolio , two forces act:
The process pressure
It makes the measuring component of the pressure switch react. The instruments are therefore designed in two ways. In the case of low process pressures, mechanical pressure switches therefore include a diaphragm (because of the large surface area absorbing the pressure), whereas, at higher pressures, they have a piston with a small surface area.
The force of the preloaded spring
This is adjusted via the adjustment screw of the pressure switch. The further the screw is turned in, the stronger the force of the spring that the measuring element has to overcome. This is accompanied by an increase in the switch point?s value. Refundable was created based on the required switching range. Relative to the functional principle of the mechanical pressure switch, the switch point is defined by the amount of spring preload. It really is set when the pressure increases, and the reset point is set accordingly when the pressure decreases.
What should be considered when choosing the setting range?
When selecting the setting range, it is essential for the user to take into account the utmost system pressure to that your pressure switch is subjected. In the case of the WIKA compact instruments, PSM01 and PSM02 (with adjustable hysteresis), for instance, that is 60 bar (diaphragm) and 350 bar (piston).
The setting range is smaller compared to the overload safety. Therefore pressure spikes could be absorbed. That is important, for instance, for idle-running protection in pumps. There, the machine pressure can be many times greater than the switching value. Therefore, the PSM01 and PSM02 pressure switches in the piston version have a switching selection of up to 320 bar. The diaphragm versions of these two models can switch up to a maximum of 16 bar. The comparatively small range is explained by the particularly sensitive measuring element, that provides high repeatability. A larger switching and overpressure range would consequently require a stronger diaphragm ? at the trouble of repeatability.
Note
More info on the PSM01 and PSM02 pressure switches can be found on the WIKA website. You want to buy pressure switches? Inside our WIKA online-shop you will find a few of our standard designs. Should you have further questions, your contact will gladly assist you to.
Also read our posts
So how exactly does one set the switch point for mechanical pressure switches?
Mechanical vs. electronic pressure switches: Application areas
Mechanical vs. electronic pressure switches: Functionality