A wind direction and a wind speed are readily and accurately estimated at a desired position without using a wind direction and velocity sensor. Movement instruction means of a wind estimation system instructs an unmanned aerial vehicle (UAV), which includes a sensor unit that detects information about a position change, to move. Fall control means causes the UAV to free fall after the UAV is moved according to the instruction of the movement instruction means. Estimation means estimates at least one of a wind direction and a wind speed at a fall position based on the information about the position change detected by the sensor unit during a fall of the UAV.

A method and apparatus to electronically sense air flow and close a switch when air flow is adequate to operate an electric heater, HVACR system, or other apparatus. The apparatus is more reliable than electro-mechanical devices often used for this purpose.

Methods and apparatuses for indicating the presence of a threshold directional differential pressure between separated adjacent spaces. An inclined conduit contains at least one movable element that indicates whether the pressure difference between the two spaces is at least as high as a threshold pressure difference. The apparatus may include an on-board pitch indicator and a roll indicator which are used together to calibrate the apparatus and its installation. The apparatus may provide only one or more discrete number of pressure difference set points and be non-adjustable once installed. The inclined conduit may be non-rotatable relative to the baseplate, and the baseplate may be rotatable to change threshold pressure difference set points. The apparatus may provide a tamper-resistant indication of whether a threshold pressure differential is present.

Methods and apparatuses for indicating the presence of a threshold directional differential pressure between separated adjacent spaces. An inclined conduit contains at least one movable element that indicates whether the pressure difference between the two spaces is at least as high as a threshold pressure difference. The apparatus may include an on-board pitch indicator and a roll indicator which are used together to calibrate the apparatus and its installation. The apparatus may provide only one or more discrete number of pressure difference set points and be non-adjustable once installed. The inclined conduit may be non-rotatable relative to the baseplate, and the baseplate may be rotatable to change threshold pressure difference set points. The apparatus may provide a tamper-resistant indication of whether a threshold pressure differential is present.

Methods and apparatuses for indicating the presence of a threshold directional differential pressure between separated adjacent spaces. An inclined conduit contains at least one movable element that indicates whether the pressure difference between the two spaces is at least as high as a threshold pressure difference. The apparatus may include an on-board pitch indicator and a roll indicator which are used together to calibrate the apparatus and its installation. The apparatus may provide only one or more discrete number of pressure difference set points and be non-adjustable once installed. The inclined conduit may be non-rotatable relative to the baseplate, and the baseplate may be rotatable to change threshold pressure difference set points. The apparatus may provide a tamper-resistant indication of whether a threshold pressure differential is present.

Embodiments relate to a leak detection device. In some embodiments, the leak detection device can be used within a backflow preventer to detect faulty or degraded operation of the backflow preventer or plumbing system instability. Embodiments of the leak detection device can include a movable magnetic element and a reed switch or electrical conductor element. When a leak occurs, fluid causes the movable magnetic element to move relative to the reed switch or electrical conductor element and cause the reed switch or electrical conductor element to generate a signal.

Methods and apparatuses for indicating the presence of a threshold directional differential pressure between separated adjacent spaces. An inclined conduit contains at least one movable element that indicates whether the pressure difference between the two spaces is at least as high as a threshold pressure difference. The apparatus may include an on-board pitch indicator and a roll indicator which are used together to calibrate the apparatus and its installation. The apparatus may provide only one or more discrete number of pressure difference set points and be non-adjustable once installed. The inclined conduit may be non-rotatable relative to the baseplate, and the baseplate may be rotatable to change threshold pressure difference set points. The apparatus may provide a tamper-resistant indication of whether a threshold pressure differential is present.

A weather sensing system mountable on a tubular member. The weather sensing system includes a weather sensor housing including removably attached first and second housing portions. The first housing portion includes a first open channel and the second housing portion including a second open channel aligned with and opening toward the first open channel. The first and second open channels form an enclosed channel for receiving and fixing the weather sensing system to the tubular member.

A wind direction and a wind speed are readily and accurately estimated at a desired position without using a wind direction and velocity sensor. Movement instruction means of a wind estimation system instructs an unmanned aerial vehicle (UAV), which includes a sensor unit that detects information about a position change, to move. Fall control means causes the UAV to free fall after the UAV is moved according to the instruction of the movement instruction means. Estimation means estimates at least one of a wind direction and a wind speed at a fall position based on the information about the position change detected by the sensor unit during a fall of the UAV.

A method and apparatus to electronically sense air flow and close a switch when air flow is adequate to operate an electric heater, HVACR system, or other apparatus. The apparatus is more reliable than electro-mechanical devices often used for this purpose.