Precision monitoring of gas pressures with the additional benefit of automatic changeover of gas supply from empty to reserve tanks � resulting in substantial time and cost savings.anguard Manifold system will automatically switch over from an empty tank to a reserve. Alarm panel audibly and visually indicates that a tank has switched � alerting office personnel it is time to contact your gas supply company. The results are substantial time savings as well as more efficient gas usage. The Vanguard Alarm panel also provides an additional safety feature allowing the user to shut off the gas flow from the alarm panel vs. at the Manifold.