Does anyone know a quick and dirty way to calculate MTTR? We have two kinds of solenoid valves, one is ISO rated, the other is not. I want to prove that the MTTR of the ISO rated valve is not significantly different from that of the non ISO rated valve. We have the capability of actually disassembling and reassembling both valves to get an accurate measure. Is there a formula I can plug the values into? Thanks for any help. The results of this analysis could save my company $40,000.