Yeah, i talked to the manufacturer and minimum is 40kN and recommended 45kN. I also find it extremly high, i was a bit surprised that it was so high. I don't know if there is double springs or not....
I solved it with a block cylinder:
https://shop.amf.de/application/amf_...SEITE:Liste)=Z
...together with a pneumatic pump:
https://shop.amf.de/application/amf_...SEITE:Liste)=Z
....with the correct pneumatic valves and pressure sensors and a bit of control, I believe i'll get both a fairly fast release and the pressure i need to release the tool...I'll know later if this works :-)