The invention relates to a method for performing a function or an operation involving a material andor a device, in particular a non-gaseous material such as a biological material or an electronic material subjected to an operation as a scientific investigation, a medical test or a handling during production, under a gaseous atmosphere in an inner chamber. A base station is wireless two-way coupled to the mobile unit. The apparatus then generates a fee label indicative of the determined fee, e. The connection logic typically connects to a monitoring server and receives the periodically updated data points associated with the fuel monitor, the monitoring server being coupled to a number of fuel monitors via a network. The light sampling lens is imaged by the image sensor to produce an indication of light intensity at various elevations.