Abstract: A method of detecting gas includes determining and storing, by a controller, a zero level of a photoionization detector using ambient air inflow when an ultraviolet lamp is in a turned OFF state, wherein the stored zero level is based on an ambient temperature; sampling, by the controller, an output of a detector electrode of the photoionization detector when the ultraviolet lamp is in a turned ON state; and comparing the sampled output of the detector electrode to the stored zero level to determine if a threshold concentration of a gas is present.

Abstract: A method of detecting gas includes determining and storing, by a controller, a zero level of a photoionization detector using ambient air inflow when an ultraviolet lamp is in a turned OFF state, wherein the stored zero level is based on an ambient temperature; sampling, by the controller, an output of a detector electrode of the photoionization detector when the ultraviolet lamp is in a turned ON state; and comparing the sampled output of the detector electrode to the stored zero level to determine if a threshold concentration of a gas is present.

Abstract: A method of detecting gas includes determining and storing, by a controller, a zero level of a photoionization detector using ambient air inflow when an ultraviolet lamp is in a turned OFF state, wherein the stored zero level is based on an ambient temperature; sampling, by the controller, an output of a detector electrode of the photoionization detector when the ultraviolet lamp is in a turned ON state; and comparing the sampled output of the detector electrode to the stored zero level to determine if a threshold concentration of a gas is present.

Abstract: A method of detecting gas includes determining and storing, by a controller, a zero level of a photoionization detector using ambient air inflow when an ultraviolet lamp is in a turned OFF state, wherein the stored zero level is based on an ambient temperature; sampling, by the controller, an output of a detector electrode of the photoionization detector when the ultraviolet lamp is in a turned ON state; and comparing the sampled output of the detector electrode to the stored zero level to determine if a threshold concentration of a gas is present.

Abstract: Embodiments relate generally to systems and methods for shielding electrodes (204,205,504,505) within a photoionization detector (100). A photoionization detector (100) may comprise an ultraviolet radiation source (130); one or more detector electrodes (204,205,504,505); one or more collection surfaces (224,225,524,525) extending vertically from the detector electrodes (204,205,504,505); and a shielding material (206,506) located between the ultraviolet radiation source (130) and the one or more detector electrodes (204,205,504,505), wherein the ultraviolet radiation (130) does not directly impinge on at least a portion of the one or more detector electrodes (204,205,504,505). The one or more collection surfaces (224,225,524,525) may comprise a surface area that is not covered by the shielding material (206,506).

Abstract: A method of detecting gas includes determining and storing, by a controller, a zero level of a photoionization detector using ambient air inflow when an ultraviolet lamp is in a turned OFF state, wherein the stored zero level is based on an ambient temperature; sampling, by the controller, an output of a detector electrode of the photoionization detector when the ultraviolet lamp is in a turned ON state; and comparing the sampled output of the detector electrode to the stored zero level to determine if a threshold concentration of a gas is present.

Abstract: A photoionization detector (100) comprises an ultraviolet radiation source (130); one or more detector electrodes (204 and 205); and a shielding material (206) located between the ultraviolet radiation source (130) and the one or more detector electrodes (204 and 205), wherein the ultraviolet radiation (240) does not directly impinge on any part of the one or more detector electrodes (204 and 205). A method for gas detection comprises exposing a photoionization detector (100) to an environment containing a target gas; and shielding the one or more detector electrodes (204 and 205) from direct impingement from the ultraviolet radiation (240) via the shielding material (206).

Abstract: A method of detecting gas includes determining and storing, by a controller, a zero level of a photoionization detector using ambient air inflow when an ultraviolet lamp is in a turned OFF state, wherein the stored zero level is based on an ambient temperature; sampling, by the controller, an output of a detector electrode of the photoionization detector when the ultraviolet lamp is in a turned ON state; and comparing the sampled output of the detector electrode to the stored zero level to determine if a threshold concentration of a gas is present.

Abstract: A method of detecting gas with a photoionization detector (PID) system. The method includes powering on a photoionization detector, turning off an ultraviolet lamp of the photoionization detector by a controller of the PID system and keeping it turned off during the zero calibration procedure, flowing ambient air from a surrounding environment by a fan of the photoionization detector system past a detector electrode of the photoionization detector, processing an output of the detector electrode by the controller to determine a zero level of the photoionization detector, and storing the zero level in a memory of the photoionization detector system. The photoionization detector system in a detecting mode compares an output of the detector electrode to the zero level to determine if a threshold concentration of a gas is present.

Abstract: Embodiments relate generally to systems and methods for shielding electrodes (204,205,504,505) within a photoionization detector (100). A photoionization detector (100) may comprise an ultraviolet radiation source (130); one or more detector electrodes (204,205,504,505); one or more collection surfaces (224,225,524,525) extending vertically from the detector electrodes (204,205,504,505); and a shielding material (206,506) located between the ultraviolet radiation source (130) and the one or more detector electrodes (204,205,504,505), wherein the ultraviolet radiation (130) does not directly impinge on at least a portion of the one or more detector electrodes (204,205,504,505). The one or more collection surfaces (224,225,524,525) may comprise a surface area that is not covered by the shielding material (206,506).

Abstract: A photoionization detector (100) comprises an ultraviolet radiation source (130); one or more detector electrodes (204 and 205); and a shielding material (206) located between the ultraviolet radiation source (130) and the one or more detector electrodes (204 and 205), wherein the ultraviolet radiation (240) does not directly impinge on any part of the one or more detector electrodes (204 and 205). A method for gas detection comprises exposing a photoionization detector (100) to an environment containing a target gas; and shielding the one or more detector electrodes (204 and 205) from direct impingement from the ultraviolet radiation (240) via the shielding material (206).

Abstract: A method of detecting gas with a photoionization detector (PID) system. The method includes powering on a photoionization detector, turning off an ultraviolet lamp of the photoionization detector by a controller of the PID system and keeping it turned off during the zero calibration procedure, flowing ambient air from a surrounding environment by a fan of the photoionization detector system past a detector electrode of the photoionization detector, processing an output of the detector electrode by the controller to determine a zero level of the photoionization detector, and storing the zero level in a memory of the photoionization detector system. The photoionization detector system in a detecting mode compares an output of the detector electrode to the zero level to determine if a threshold concentration of a gas is present.

Abstract: The present invention provides a multi-stage double-acting traveling-wave thermoacoustic system, comprising three elementary units, each elementary unit comprises a linear motor and a thermoacoustic conversion device; the linear motor comprises a piston and a cylinder, the piston can perform a straight reciprocating motion in the cylinder; each thermoacoustic conversion device comprises a main heat exchanger and a heat regenerator connected in sequence, and the heat regenerator is of a ladder structure; a set of a non-normal-temperature heat exchanger, a thermal buffer tube and an auxiliary heat exchanger is connected at each ladder of the heat regenerator; and the main heat exchanger and the auxiliary heat exchanger of each thermoacoustic conversion device are connected to cylinder cavities of different linear motors respectively forming a loop structure for flow of a gas medium.

Abstract: The present invention discloses a heat-actuated double-acting traveling-wave thermoacoustic refrigeration system, comprising at least three elementary units; each elementary unit comprises a thermoacoustic engine, a thermoacoustic refrigerator, and a resonance device; the thermoacoustic engine and the thermoacoustic refrigerator comprise a main heat exchanger, a heat regenerator, a non-normal-temperature heat exchanger, a thermal buffer tube, and an auxiliary heat exchanger connected in sequence; the resonance device comprises a sealed housing, a moving part is provided in the housing for a reciprocating motion; the moving part separates the housing into at least two chambers; the main heat exchanger and auxiliary heat exchanger of each thermoacoustic engine and thermoacoustic refrigerator respectively connects to chambers of different housing, forming dual-loop structure of gas medium flow.

Abstract: The present invention provides a single-stage double-acting traveling-wave thermoacoustic system, comprising three elementary units; each unit comprises a linear motor and a thermoacoustic conversion device. The linear motor comprises a cylinder and a piston; the piston can perform straight reciprocating motion in the cylinder. The thermoacoustic conversion device comprises a first heat exchanger, a heat regenerator, a second heat exchanger, a thermal buffer tube and a third heat exchanger connected in sequence, the first heat exchanger and the third heat exchanger of each thermoacoustic conversion device are connected to cylinder cavities of different linear motors respectively, forming a loop structure of a gas medium flow. The system comprises a thermal buffer tube and a third heat exchanger, making the temperature of gas medium given feedback to the cylinder cavity of another linear motor be close to the room temperature, ensuring the piston and cylinder working at room temperature.

Abstract: The present invention provides a multi-stage double-acting traveling-wave thermoacoustic system, comprising three elementary units, each elementary unit comprises a linear motor and a thermoacoustic conversion device; the linear motor comprises a piston and a cylinder, the piston can perform a straight reciprocating motion in the cylinder; each thermoacoustic conversion device comprises a main heat exchanger and a heat regenerator connected in sequence, and the heat regenerator is of a ladder structure; a set of a non-normal-temperature heat exchanger, a thermal buffer tube and an auxiliary heat exchanger is connected at each ladder of the heat regenerator; and the main heat exchanger and the auxiliary heat exchanger of each thermoacoustic conversion device are connected to cylinder cavities of different linear motors respectively forming a loop structure for flow of a gas medium.

Abstract: The present invention discloses a heat-actuated double-acting traveling-wave thermoacoustic refrigeration system, comprising at least three elementary units; each elementary unit comprises a thermoacoustic engine, a thermoacoustic refrigerator, and a resonance device; the thermoacoustic engine and the thermoacoustic refrigerator comprise a main heat exchanger, a heat regenerator, a non-normal-temperature heat exchanger, a thermal buffer tube, and an auxiliary heat exchanger connected in sequence; the resonance device comprises a sealed housing, a moving part is provided in the housing for a reciprocating motion; the moving part separates the housing into at least two chambers; the main heat exchanger and auxiliary heat exchanger of each thermoacoustic engine and thermoacoustic refrigerator respectively connects to chambers of different housing, forming dual-loop structure of gas medium flow.