Abstract: According to at least one aspect, a fluid flow tube can define a first cavity for receiving a first ultrasonic sensor. The first cavity can have a first longitudinal axis intersecting a longitudinal axis of the fluid flow tube. The fluid flow tube can define a second cavity for receiving a second ultrasonic sensor. The second cavity can have a second longitudinal axis aligned with the first longitudinal axis. The fluid flow tube can define a third cavity having a first transverse cross sectional area larger than a second transverse cross sectional area of the fluid flow tube and sized to receive a shut-off valve.

Abstract: According to at least one aspect, a monolithic sensor mount can include a first cylindrical portion and a second cylindrical portion. The first cylindrical portion can have a first diameter and the second cylindrical portion can have a second diameter larger than the first diameter. The second cylindrical portion defining a recess region to host an ultrasonic transducer. The second cylindrical portion can have an outer surface that defines a male thread to mechanically engage a female thread of a cavity within a fluid flow tube configured to host the sensor mount.

Abstract: According to at least one aspect, the present disclosure is directed to leak detection. There is pressure sensor for measuring pressure of fluid within a hollow structure, a shut-off valve for controlling fluid flow through the hollow structure, and a processor communicatively coupled to the pressure sensor and to the shut-off valve. The processor can acquire, from the pressure sensor, a first pressure measurement of the fluid while the shut-off valve is in an open state, and a second pressure measurement of the fluid while the shut-off valve is in a closed state. The processor can detect a fluid leak event based on the first and second pressure measurements.

Abstract: According to at least one aspect, a monolithic sensor mount can include a first cylindrical portion and a second cylindrical portion. The first cylindrical portion can have a first diameter and the second cylindrical portion can have a second diameter larger than the first diameter. The second cylindrical portion defining a recess region to host an ultrasonic transducer. The second cylindrical portion can have an outer surface that defines a male thread to mechanically engage a female thread of a cavity within a fluid flow tube configured to host the sensor mount.

Abstract: According to at least one aspect, a fluid flow tube can define a first cavity for receiving a first ultrasonic sensor. The first cavity can have a first longitudinal axis intersecting a longitudinal axis of the fluid flow tube. The fluid flow tube can define a second cavity for receiving a second ultrasonic sensor. The second cavity can have a second longitudinal axis aligned with the first longitudinal axis. The fluid flow tube can define a third cavity having a first transverse cross sectional area larger than a second transverse cross sectional area of the fluid flow tube and sized to receive a shut-off valve.

Abstract: A chair timer is disclosed adapted to aid a user seated in a chair equipped with such a chair timer in the reduction of serious health issues associated with prolonged sitting, and crowd management and/or seating management. In various embodiments associated systems and methods of the chair timer are included. In one embodiment, the chair timer includes a sensor to detect movement, a microcontroller to communicate with one or more sensors and other components of the chair timer, a power supply, a switch to control the time and other settings, an alert device by which the user is altered to the passage of a certain amount of time, and additional user-operable control settings and switches by which the device is controlled, and by which control may be accessed and controlled via a website, smart phone, PDA, or the like, through wired or wireless technologies such as Bluetooth, Zigbee, WiFi, or the like.