At least two magnetic-reed switches are mounted at spaced angular locations beneath the scale of a Bourdon-type pressure gage wherein the needle tip carries a permanent magnet. The reed switches change their respective states upon sensed-pressure descent to first and second predetermined levels of pressure, respectively indicative of different impending needs to switch a new container into the line of pressure delivery to beverage-dispensing apparatus. In one form, the impending needs reflect corresponding situations of remaining gas content of the cylinder, for room temperature storage and for cold-room storage, respectively; and a manual switch at the gage enables the gage to perform, as is appropriate for the particular situation of stored-container temperature. In another form, the second or additional magnetic-reed switch is positioned beneath the scale for operation upon a sensed low level of gas-pressure effectiveness for beverage dispensing. In all cases, wiring connections to the switches of the gage operate indicator-lamp/alarm functions at a remote monitoring-unit location, whereby management personnel may take responsible action.