An example monitoring device for a steam trap includes: an enclosure; a sensor subsystem housed in the enclosure, the sensor subsystem to measure a property of the steam trap; a memory housed in the enclosure; a communications interface housed in the enclosure and configured to communicate with a server; a processor housed in the enclosure and interconnected to the sensor subsystem, the memory, and the communications interface, the processor configured to: obtain, from the sensor subsystem, data representing the property of the steam trap; extract a set of key features from the data; and send, via the communications interface, the set of key features to the server for further processing to detect a failure.