sail switch

A sail switch, vane switch or flow switch is a mechanical switch that is actuated on or off in response to the flow or non-flow of a fluid such as air or water.{{cite journal |author=Matthew J. Darr |display-authors=et. al. |title=A Robust Sensor for Monitoring the Operational Status of Agricultural Ventilation Fans |journal=Transactions of the ASABE |date=2007 |volume=50 |issue=3 |page=1019 |doi=10.13031/2013.23142}} A sail switch typically operates through the use of a paddle or a diaphragm which gets displaced due to the force of fluid or air moving past it. Sail switches find application in the detection of fluid flow and measurement of fan speeds.{{cite journal |author=Steven J. Hoff |display-authors=et. al. |title=Real-Time Airflow Rate Measurements from Mechanically Ventilated Animal Buildings |journal=Journal of the Air & Waste Management Association |date=June 2009 |volume=59 |issue=6 |page=685 |doi=10.3155/1047-3289.59.6.683|pmid=19603736 |s2cid=46390769 |doi-access=free }} A sail switch might be used to protect a fan forced pellet stove, central heating system, electric heating element from being energized before the air flow from the blower is established. Sail switches might also be used to alarm if a ventilation fan in a hazardous location fails and air flow has stopped. For some HVAC systems, a sail switch can activate an electronic air cleaner, a humidifier, or other equipment in response to airflow from the system fan.{{cite web

|url=http://electronicaircleaners.com/s688a1007.aspx|title=Honeywell S688A1007 Sail Switch SPDT|work=Bel-Aire|access-date=20 December 2015}}