A detection method includes calibration mode of calibrating sensor with low-concentration gas being caused to flow along direction from the sensor toward an adsorption part, first detection mode of, after the calibration mode, detecting chemical substance with sample gas being caused to flow along the direction from the sensor toward the adsorption part, first adsorption mode of adsorbing, by the adsorption part, the chemical substance during an execution time period including time period overlapping at least part of an execution time period of the first detection mode, second adsorption mode of, after the first adsorption mode, adsorbing, by the adsorption part, the chemical substance with the sample gas being caused to flow along direction from the adsorption part toward the sensor, and second detection mode of desorbing, from the adsorption part, the chemical substance adsorbed in the first and second adsorption modes and detecting the chemical substance by the sensor.

The disclosure includes a gas chromatograph for underground use comprising a fixing board. In some embodiments, the gas chromatograph for underground use includes a power connection socket, at least one three-way solenoid valve, a quantitative loop, an analysis module, a communication main board, a data transmission device, a sample injection membrane valve, and a gas injection pump detachably coupled to the fixing board. In some embodiments, the quantitative loop and the sample injection membrane valve are arranged and configured to couple to at least one of the at least one three-way solenoid valves.

Mercury vapor reference systems, devices, and method for testing mercury vapor analyzers. A variable volume dilution chamber such as a syringe selectively receives mercury vapor and a dilution gas to dilute the mercury vapor prior to dispensing into an airflow for testing by the mercury vapor analyzer.

Embodiments relate generally to systems and methods for calibrating a gas detector. Some embodiments may include a gas detector comprising one or more sensing elements operable to detect volatile organic compounds (VOC), and a probe operable to provide air flow into the gas detector, wherein the probe comprises: a housing operable to attach to a main body of the gas detector and operable to hold a calibration tube during calibration of the gas detector; a cap operable to attach to the housing and operable to fit over and cover the calibration tube; and one or more inlets, wherein when a calibration tube is inserted into the probe, the air flows through the calibration tube. In some embodiments of the gas detector, the calibration tube inserted into the probe comprises activated carbon fiber (ACF) filter material.

A method of operating a gas sensor for a gas analyte including a sensing component includes, in a first mode, interrogating the sensor by periodically applying an electrical signal to the sensing component of the sensor, measuring sensor response to the electrical signal which is indicative of a sensitivity of the sensor each time the electrical signal is applied to the sensing component, determining whether one or more thresholds have been exceeded based upon the sensor response determined each time the electrical signal is applied to the sensing component, and entering a second mode, different from the first mode in analysis of the sensor response to the periodically applied electrical signals, if one or more thresholds are exceeded.

A rebreather apparatus includes at least one pressurized container of oxygen, at least one pressurized container of a diluting gas, and at least one valve to supply the oxygen and diluting gas to a rebreathing loop. The valve is controlled by a signal from at least one oxygen sensor, wherein the oxygen and diluting gas combine to form a breathing gas that is circulated by the rebreathing loop. At least one container of calibrating gas stores the calibrating gas at ambient pressure and temperature. At least one valve is connected to the at least one oxygen sensor presenting the calibrating gas to the oxygen sensor during calibration of the oxygen sensor and presenting the breathing gas to the oxygen sensor at all other times.

A method and apparatus for operating a multi-gas sensor are disclosed. In an embodiment, a method includes providing at least one calibration input comprising sensor design data of the multi-gas sensor, which varies dependent on production process parameters, and/or sensor production process parameter data of the multi-gas sensor, and/or measurement results of the multi-gas sensor captured when the multi-gas sensor is exposed to one of the gases or a gas mixture to be detected and/or sensed by the multi-gas sensor; providing a trained neural network including an input layer with K input nodes, an output layer with L output nodes and at least one hidden layer; storing each calibration input as a fixed input to a corresponding input node of the trained neural network; and providing a multi-gas sensor output for at least a part of the gases to be detected and/or sensed by the multi-gas sensor dependent on the trained neural network and actual measured sensor values from the sensor elements.

A method of calibrating a detector that includes a volatile organic compound (VOC) sensor is provided. The method includes assembling the detector with the VOC sensor for field deployment and calibrating the VOC sensor using carbon monoxide (CO) as a calibrant prior to the field deployment.

An apparatus for determining a presence, a concentration or a change in concentration of a target material in an environment is disclosed. The apparatus comprises first and second sensors configured to respond to the target material. The apparatus further comprises a fluid inlet in fluid communication with the environment, and a valve assembly having a first and second configuration. In the first configuration, the fluid inlet is in fluid communication with only the first sensor. In the second configuration, the fluid inlet is in fluid communication with the first sensor and the second sensor.

The present invention relates to an information processor. The information processer comprises a diagnostic unit for diagnosing a state of a humidity sensor, the diagnostic unit diagnosing that the humidity sensor is in a deteriorated state when days on which a proportion of detection data of the humidity sensor indicating 100% humidity out of all detection data for one day is equal to or greater than a reference proportion, have persisted for a reference period.