A sensor arrangement is provided for temperature measurement in melts, in particular in metal or cryolite melts having a melting point above 600\xb0 C. When a user turns off at least one of the plurality of chambers of the refrigerator, a power-off state display apparatus of the refrigerator displays \u201cOFF\u201d characters on a display unit, thus confirming that a particular chamber has been turned off. The flow cache is configured to determine whether the lookup key is stored in the flow cache, and, when the lookup key is stored in the flow cache, retrieve a stored result associated with the lookup key and output the stored result. Consequently, air cannot easily pass out of the inflatable device through the inlet port when the device is inflated or being inflated. On one shaft there are at least two deflection wheels which have receiving slots in identical positions and that the shaft can be inclined relative to the transport direction of the sheet feed device.