Espresso brew pressure profiling: dual OPV on the Rocket Giotto
![Afbeelding](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiwDq57Mzxov9QAqfP_Ua3w6vp9TAnopOr-SR57lruf9oM55rtLtf1l1MGl15M1X2G4iuL4uh3Iz4U28Wp2eFUV0A00JJ6RWB4HWRGVtnKqjC6Zn3e8DFS6Vh1_62FyKAkI2vX3fKOCKBbT/s640/01peterbelt-dualopv_MG_7614.jpg)
Yesterday morning I took my Rocket Giotto to visit Peter van der Weerd from http://www.kafko.nl in his espresso machine workshop. He has made me a temperature probe to fit in a portafilter basket: (I will post more about this nifty device soon) Since I was there anyway, he took an extra back panel and cut out a square so I could change the setting of the OPV while working with the machine. This way, I wouldn't need to disassemble the covers if I wanted to change the brew pressure setting: I had been lowering the brew pressure on the OPV but noticed that it would leak water when turned down below 8 bar. Here a few images of this original OPV connection: To be able to easily change the setting of this OPV through the back panel opening, Peter created a bend in the spanner: An image of the spring inside this OPV: Peter could cut the spring to allow the threaded part to go in deeper but he didn't like this idea as the spring has its own u