As a kit reviewer, I commonly hit the water in a set of kit that’s completely unfamiliar to me.
Although I was also using a gas-integrated computer on that test trip, having a dial pressure gauge was reassuring.
That’s because, on first dives with a test computer, I’m not always sure what the read-outs are telling me…
The Mares Mission 1 has a 40mm-diameter dial. The main body is brass, although you can’t see this touch of quality because it’s protected from shock by a sturdy rubber console.
The main dial is phosphorescent white with black needle and indices. There’s a red caution zone from 50 bar to zero, plus two other coloured zones between 50-200 and 200-450 bar.
Although rated to 450, gauges are meant to have a 25% overspill safety factor, so it’s really for use with 300 bar cylinders that have been “generously” filled.
As required by law, a relief port is built in. This vents automatically and safely if the internal bourdon tube fails and high-pressure air leaks out of it.
The most common cause for this problem with SPGs of any brand is a wet air-fill, or letting water into your first stage.