Gas detector in industrial refrigeration processes and biological degradation processes, including exhaled breath. Depending on the required sensitivity, different types of sensors are used (e.g., flame ionization detector, semiconductor, electrochemical, photonic membranes). Detectors usually operate near the lower exposure limit of 25ppm; however, ammonia detection for industrial safety requires continuous monitoring above the fatal exposure limit of 0.1%. There are several different sensors that can be installed to detect hazardous gases in a residence. Carbon monoxide is a very dangerous, but odorless, colorless gas, making it difficult for humans to detect. Carbon monoxide detectors can be purchased for around US$20–60. Many local
Lawn mower very smooth lawn surface to operate properly without bottoming out the cutter bar. Hover mowers are powered rotary push lawn mowers that use an impeller above the spinning blades to drive air downward, thereby creating an air cushion that lifts the mower above the ground. The operator can then easily move the mower as it floats over the grass. Hover mowers are necessarily light in order to achieve the air cushion and typically have plastic bodies with an electric motor. The most significant disadvantage, however, is the cumbersome usability in rough terrain or on the edges of lawns, as the