Apparatuses and methods for compressed fluid vessel monitoring can permit a user to more easily order replacement vessels, monitor use, monitor inventory and return empty vessels. Embodiments can utilize a collar connectable to a vessel to help facilitate such functionality. The collar can be adapted to transmit signals to a data processing system. The data processing system can be adapted to permit a user to track the location and fill status of the vessel as well as order a replacement vessel and disposal or return of an empty vessel. Instrumented vessels can also convey sensor data to help identify a leak condition or other condition of the vessel. In some embodiments, the data processing system can be adapted for integration into a user's inventory system and/or purchasing system as well as a supplier's system to facilitate communications concerning vessel fill status, reorder, and/or vessel return.

A barometric level gauge includes: a housing, including a side wall, and a top cover plate and an inner partition plate respectively connected to the side wall, where a device mounting cavity is formed between the top cover plate and the inner partition plate and a vent chamber is formed on a side, back to the top cover plate, of the inner partition plate, the vent chamber is in communication with atmosphere, and the inner partition plate is provided with a first vent connecting the device mounting cavity to the vent chamber; and a pressure sensor, mounted in the device mounting cavity, where the pressure sensor includes a first sensitive element for sensing air pressure in the device mounting cavity. A problem of damage, caused by water, to the internal devices may be avoided.