A tank inventory signaling apparatus that has bins with aligned parallel rows of industrial gas cylinder tanks stored in a cage having upright posts forming fences that define storage bins. Tanks in each bin are separated from each other by hinged gates that can be closed by magnetic or electronic latches. The logic state of all latches, open or closed, is reported to a local server that communicates gate state logic to a remote server. Tank inventory is inferred by opening of gates since it is necessary to open a gate to remove a tank. All gates in a cage have a collective gate state. Changes in the gate states of all tank storage units is reported to a remote server having associated tank management and supply software and route management software. In this manner, local tank usage can be tracked at remote locations for resupply of tanks and delivery of replacement tanks can be optimized.