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.

A Discrete Sample Introduction Module (DSIM) apparatus includes an internal tubing system to receive into the DSIM apparatus a discrete gas sample having a received concentration. A plurality of valves selectively partitions the internal tubing system to form a plurality of loops corresponding to a plurality of loop volumes to contain the discrete gas sample. The plurality of loop volumes receives a carrier gas to dilute the discrete gas sample to a plurality of preselected dilutions. The DSIM apparatus circulates a given one of the plurality of preselected dilutions for analysis by a spectrometer coupled to the DSIM apparatus.

A method for removing a halogen fluoride in a mixed gas by reacting the mixed gas containing a halogen fluoride including bromine or iodine with a removing agent, wherein the removing agent is a chloride, bromide or iodide of potassium, sodium, magnesium, calcium and barium. Also disclosed is a quantitative analysis method as well as a quantitative analyzer for a gas component contained in a hydrogen fluoride mixed gas, the method characterized by reacting a mixed gas containing a halogen fluoride and another gas component with a removing agent, thereby removing the halogen fluoride in the mixed gas, further removing produced by-products, and quantitatively analyzing a residual gas by a gas chromatograph.

A filed portable analyzer capable of performing both the sampling and analytical procedures required by U.S. EPA Method 25 utilizing a small volume injection of sample onto a cryotrap cooled by a Stirling linear drive charged with helium to replace the field sampling condensate trap. The cryotrap is followed by the specified sorbent column/traps to ensure precise compatibility with prior reported compliance test results. The analytical system utilizes an oxidation catalyst and reduction catalyst to remove the potential for differing response factors on the FID from different compounds.

The invention relates to an electrochemical gas sensing apparatus for sensing one or more analytes, such as NO.sub.2 and/or O.sub.3, in a sample gas and a method of using same. The apparatus uses Mn.sub.2O.sub.3 as a filter for ozone. The Mn.sub.2O.sub.3 may take the form of a powder which may be unmixed, mixed with various PTFE particles sizes, formed into a solid layer deposited onto a membrane and/or pretreated with NO.sub.2.

A device for detecting a non-condensable gas including a tube having an open end and a closed end, the tube and the closed end being closed with respect to a fluid, the open end open to allow the fluid to move into and out of the tube, and the tube configured to allow a condensed portion of the fluid to be removed from the tube by gravitation. The device includes a heat sink configured to extract heat from the tube at the closed end. The device further includes a heat source configured to supply heat to the open end of the tube and at least one thermometer configured to measure a temperature at a specific portion of the device or the fluid inside the tube.

A gas sensing device includes chemoresistive gas sensing elements, wherein a material composition of a first chemoresistive gas sensing element is similar to a material composition of a second chemoresistive gas sensing element, wherein the first chemoresistive gas sensing element is exposed to an ambient mixture of gases so that first sensing signals depend on a concentration of a first gas and on a concentration of a second gas, wherein the gas sensing device includes a gas filter so that the second sensing signals depend on the concentration of the first gas to a lesser degree than the first sensor signals and so that the second sensing signals depend on the concentration of the second gas, and wherein the gas sensing device estimates the concentration of the first gas and/or the concentration of the second gas based on the first sensing signals and the second sensing signals.

Systems and methods for analyzing a gas are provided. In some embodiments, the system includes: at least one scrubber including a scrubber material that removes at least one sulfur compound from the gas to produce a scrubbed gas; at least one gas sensor in fluid communication with the at least one scrubber, the at least one gas sensor sensing at least one remaining sulfur compound in the scrubbed gas. In some embodiments, the systems and methods disclosed herein may be used to analyze individual odorants in a hydrocarbon gas such as natural gas.

There is provided a system including a monitoring unit that analyzes, using a sensor, components of a first gas which may include first components and a pre-separation unit disposed upstream of the monitoring unit. The pre-separation unit includes: a first supply line that supplies the first gas to the monitoring unit; a second supply line that supplies a second gas, which includes components obtained by removing the first components from the first gas using a first separator, to the monitoring unit; and an automatic valve station that periodically switches between the first supply line and the second supply line to alternately supply the first gas and the second gas to the monitoring unit.

Breath sensor apparatus and methods of use are described herein where a flow control apparatus may generally comprise a sampling chamber defining a volume and one or more openings into the sampling chamber, at least one sensor in fluid communication with the sampling chamber, wherein the at least one sensor is configured to detect the analyte. The sampling chamber may also be configured to receive the breath sample into the sampling chamber and into contact with the at least one sensor via diffusion into the sampling chamber.