Autochange regulators use a visual indicator to advise you when a cylinder has become empty and has switched over to draw gas from the other cylinder.
While some indicators start off green and others clear, they all turn red when the first cylinder is empty. Do not touch or turn the dial. When you see it turn red, that's your signal to call OnGas for a refill delivery. We will pick up the empty cylinder and replace it with a full one, and reset the regulator.
If your cylinder station has a "manual" regulator, you will need to turn on the valve on your reserrve cylinder once the first cylinder is empty. Gas is then drawn from the reserve cylinder.