Centrifugal compressors can incorporate a side stream flow of intermediate pressure vapor between stages of that compressor. The side stream flow can be controlled by a side stream injection port controlled by a capacity control valve that has a curved surface facing a flow of refrigerant from the first stage to the second stage. The capacity control valve can allow or obstruct flow through the side stream injection port. The capacity control valve can extend and retract in a direction substantially perpendicular to the direction of flow from the first stage impeller to the second stage impeller. The side stream injection port and the capacity control valve can be ring-shaped. The side stream injection port and the capacity control valve can allow at least some of the side stream to be introduced on a side of the capacity control valve opposite the curved surface.

A diagnostic system includes a fan control circuit coupled to an electric fan and a microcontroller, and a sense line coupled to the fan control circuit and the microcontroller. The fan control circuit outputs a fan command sense signal at a duty cycle through the sense line to the microcontroller. A tachometer generates a tachometer signal at a frequency indicative of the rotational speed of the electric fan. A fan tachometer circuit receives the tachometer signal and outputs the tachometer sense signal at a frequency to the microcontroller in response to the tachometer signal. The microcontroller sets a second diagnostic flag to an error value indicating that the sense line has impaired operation if the frequency of the tachometer sense signal is within a desired frequency range, and a first diagnostic flag is equal to a first error value.

The present invention provides a device and a system for simulating the buoyancy and the resistive force. The system comprises a pair of wearable devices, each of the wearable devices comprises a calf shell, a first ducted fan, a second ducted fan, a first connection component, a second connection component and a tracker. The first ducted fan and the second ducted fan operate in non-zero duty cycles for generating a first force in a first direction, and a second force in a second direction. The first direction and the second direction are in different directions. The sum of the first force and the second force are the sum of the resistive force, the buoyant force, the potential weights and the weight of the wearable device. The tracker further transmits feedback data to control system.

A compressor assembly for a portable oxygen concentrator includes a first compressor chamber having a first connector, a second compressor chamber having a second connector, and a tube having a first end having a first connection interface configured to connect to the first connector and a second end having a second connection interface configured to connect to the second connector. The first connection interface is shaped to maintain the connection between the first connector and the first connection interface in a fixed orientation and the second connection interface is shaped to maintain the connection between the second connector and the second connection interface in a fixed orientation. One or more of the first connector, the second connector, and the tube are compliant.

A ceiling fan assembly having a motor with a rotor and a stator, at least one blade operably coupled to the stator, a motor shaft extending from the stator and having an internal wire passage and a wire opening in a side of the motor shaft, with the wire opening providing access to the internal wire passage, a control mounting plate having a motor shaft opening through which the motor shaft extends and an electronic control unit carried by a side of the control mounting plate.

A ceiling fan assembly having a motor with a rotor and a stator, at least one blade operably coupled to the stator, a motor shaft extending from the stator and having an internal wire passage and a wire opening in a side of the motor shaft, with the wire opening providing access to the internal wire passage, a control mounting plate having a motor shaft opening through which the motor shaft extends and an electronic control unit carried by a side of the control mounting plate.

A blower assembly for a powered air-purifying respirator (PAPR) assembly includes: a lower housing; an upper housing connected to the lower housing, such that the upper housing and the lower housing collectively define a first interior cavity; a filter configured to filter ambient air drawn into the blower assembly; and a fan. The upper housing and the filter define a pathway for a flow of air into the first interior cavity. The fan is positioned in the first interior cavity such that, when the fan is activated, ambient air is drawn into the blower assembly and travels along the pathway into the first interior cavity for subsequent delivery out of the blower assembly. The lower housing defines an outlet port for directing breathable air out of the blower assembly for delivery to a user (e.g., via a breathing tube interconnecting a headpiece and the outlet port).

A blower assembly for a powered air-purifying respirator (PAPR) assembly includes: a lower housing; an upper housing connected to the lower housing, such that the upper housing and the lower housing collectively define a first interior cavity; a filter configured to filter ambient air drawn into the blower assembly; and a fan. The upper housing and the filter define a pathway for a flow of air into the first interior cavity. The fan is positioned in the first interior cavity such that, when the fan is activated, ambient air is drawn into the blower assembly and travels along the pathway into the first interior cavity for subsequent delivery out of the blower assembly. The lower housing defines an outlet port for directing breathable air out of the blower assembly for delivery to a user (e.g., via a breathing tube interconnecting a headpiece and the outlet port).

A method for leak detection in a system including a compressor. A first pressure differential is determined in the system via a first pressure differential indicator (PDI). The first pressure differential is converted into a first flow measurement. A second flow measurement is determined downstream of the compressor using a second PDI. The first flow measurement and the second flow measurement are compared to determine whether a leak exists between the first PDI and the second PDI.

A suspended system with orientation control. The system may have a frame, a sign attached to the frame, a plurality of sensors, at least two thrusters, and a microcontroller operatively coupled to the plurality of sensors and the thrusters. The frame is configured to be suspended from a support, and the sign is configured to display a graphic. The plurality of sensors is configured to track an orientation of the frame. The thrusters are configured to adjust the orientation of the frame. Each of the thrusters may have an axis oriented in a direction perpendicular to the frame. The microcontroller is configured to receive a selected orientation of the frame, receive the current orientation of the frame from the sensors, compare the orientation of the frame with the selected orientation, and control the thrusters to adjust the orientation of the frame into the selected orientation.