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 hydrostatic transmissions with lower cost alternatives, but these attempts, which include variable belt types, e.g., MTD's "Auto Drive", and toroidal, have various performance or perception problems that have caused their market life to be short or their market penetration to be limited. Riding lawn mowers can often mount other devices, such as rototillers/rotavators, snow plows, snow blowers, yard vacuums, occasionally even front buckets or fork-lift tines (these are more properly known as "lawn tractors" in this case, being designed for a number of tasks). The deck of a rotary mower is typically made of steel. Lighter steel is used on