Refco ECO-2-A2L-e Bedienungsanleitung Seite 10

as the alarm starts, you have three minutes to close the valve. A
solenoid valve is installed for additional safety. This solenoid valve
closes automatically if the vacuum pump is unintentionally
switched off (disconnection from the power supply). In such a case,
the vacuum that has already been generated is not lost. The
solenoid valve opens again automatically as soon as the vacuum
pump is switched on (connected to the power supply).
9
Instruction Manual