The solenoids are not going to be powered constantly. They use pilot air pressure to control a valve that then raises or lowers the air pressure. They would only run for a few seconds tops, 12V @ .6 amps. I have a dual 12V relay board I am going to use. As far as setting up the HM10's in "duplex" mode I am having issues finding that info concisely.... on forum/write up contradicts the next. I did however find one, but it did not give me very much info.
Strange type of piloted solenoid valves, then. My piloted irrigation solenoid valves, like yours, need very little current to open, BUT, they close as soon as power is removed. Bet yours do to.Paul