Abstract: A device for demonstrating the operation of gas contaminant testing apparatus and for training persons to use such apparatus. The device can be portable and allows demonstration of and training on testing apparatus in a location removed from the environment in which the gaseous medium and its gaseous and vaporous contaminants are normally found. The device uses very small contaminant samples for demonstration in order to minimize personnel exposure and inadvertent or deliberate releases to the environment. The device allows the substitutions of, for training and demonstration purposes, a harmless gaseous medium for the actual gaseous medium of interest. In a preferred embodiment, designed for demonstrating the operation of a refrigerant contaminant testing apparatus, air is susbstituted for refrigerant as the gaseous medium in which contaminants are entrained when using the device. In that embodiment, air is caused to flow through a container holding a contaminant sample of interest.