Which type of pressure switch/sensor you need for your espresso machine depends on various factors such as the brand, Type, fitting, voltage, phases, amperage, pressure reach and adjustability. Seen all these factors above can influence the working of your espresso machine.
There are 2 types of pressure switch, the analogue model and the digital pressure sensor. The digital pressure sensor can be found on various espresso machine brands such as Rancilio, La Cimbali, Nuova Simonelli, Astoria, Wega and Victoria Arduino. Some brands do use a combination of both on various models. Where the “high end” versions use pressure switches and the less economic models a pressure switch.
There are a variety of manufacturers of pressure switches such as Asco(Sirai), Parker and Ma-ter. The brands https://brooks-parts.com/nz/asco-sirai-pressure-switch-p3026Asco and Parker are mainly known for the use of them in commercial espresso machines. Where the Ma-ter pressure switches are mostly used in domestic espresso machines, especially the XP110 versions.
The rated amperage of the pressure switch does depends on the model used. For instance on the Ma-ter pressure switches this is 16A, so in the situation with 230V you would be able to control 16x230=3680W single phase. Seen there is only one connection for the live wire.
The commercial grade pressure switches, made by Asco and Parker can do between 20 and 30 amps of power. Some have single phase, so one connecting place. But other such as the famous Asco/Sirai pressure switches are made for 3 phase and have a max capacity of 30A.
The fitting on traditional pressure switches is a 1/8” BSP-G or a ¼”BSP-G. The ¼” is the most common version for pressure switches, seen they are less likely that they will break off. The 1/8” BSP-G size is found on some of the smaller Ma-ter XP110 pressure switches.
For pressure sensors this can range from a 3/8” thread to a non threaded connection, but that the sensor is held in place with screws.
The pressure reach does depend on one important question. Is the pressure switch adjustable? Seen not all pressure switches are adjustable, some have a fixed pre-set pressure. But with most analogue pressure switches the pressure can be changed by turning a screw clock or counter clockwise.
For instance the Parker and asco 3 phase pressure switch has a range of 0,5-1,4 bar, but there are also versions of the 3 phase models which start at 0,9 bar and have a high point at 1,7bar.
