We have a machine dedicated to measuring length of product and it utilizes a complex series of rollers and cylinders for routing of the material- all of that is fairly irrelevant in regards to why I'm posting. The particular Festo unit, VPPM-6TA-L-1-F-OL10H-S1, is good for up to 10 bar according to the datasheet. The valves equipped with this are capable of being manually actuated but when this is attempted we received no pressure through the valves. Initial pressure was 6 bar, far below the stated max. We were unable to manually or electronically actuate the valves until the main inlet pressure was reduced to 4 bar. There were no faults on the Festo unit as it is equipped with an LED fault indicator. I have never encountered a valve that has manual override functions for actuating not work based upon system pressure. Any insight would be greatly appreciated. The machine is currently functioning properly so there is no rush or immediate need but a better understanding of this would be great. Thanks in advance for any info you can offer.