Reed Switches can be used in a multitude of applications. Reed Switches serve as reliable sensors for many proximity or position sensing, level sensing, speed sensing, and flow sensing needs. Proximity or position sensing typically consists of detection of the position of the moving part in a mechanical system. Common examples include detection of whether or not a door is closed on a household appliance, such as a refrigerator, or in security systems where door or window opening is monitored. Level sensing normally consists of detection of the fluid level in tanks using a floating magnet. Level sensing can consist of a single fluid level reading (empty or full) or even multiple fluid levels in larger tanks. Reed Switches can be used as speed sensors in certain low-speed applications where speeds are not expected to exceed a few thousand revolutions per minute. Common examples include speed monitoring on fitness equipment such as treadmills, stationary bicycles, and elliptical cross-trainers. Reed Switches are also used in flow sensing applications where the presence of fluid flow needs to be detected. For example, in tank-less water heaters, a Reed Switch may be used to detect when water flow is initiated, which in turn can signal the ignitor to begin heating the incoming water. Reed Switches can also be used to “wake-up” the electronics in systems that are powered by batteries to help preserve battery life.