Abstract: A differential monitoring system of carbon dioxide levels within an associated building with a monitoring zone including a quantity of captured carbon dioxide and a reference zone that is spaced away from the monitoring zone. The differential monitoring system includes a first carbon dioxide monitoring inlet disposed within the monitoring zone. A second carbon dioxide monitoring inlet is disposed within the monitoring zone in spaced relation to the first carbon dioxide monitoring inlet and/or is disposed within the reference zone in spaced relation to the first carbon dioxide monitoring zone. A controller is operable to determine when a carbon dioxide level at the second carbon dioxide monitoring inlet exceeds a carbon dioxide level at the first carbon dioxide monitoring inlet by a predetermined differential threshold. The inlets can be part of an aspirated sampling system and/or part of a distributed sensor system. Methods of monitoring carbon dioxide levels are also included.

Abstract: A differential monitoring system of carbon dioxide levels within an associated building with a monitoring zone including a quantity of captured carbon dioxide and a reference zone that is spaced away from the monitoring zone. The differential monitoring system includes a first carbon dioxide monitoring inlet disposed within the monitoring zone. A second carbon dioxide monitoring inlet is disposed within the monitoring zone in spaced relation to the first carbon dioxide monitoring inlet and/or is disposed within the reference zone in spaced relation to the first carbon dioxide monitoring zone. A controller is operable to determine when a carbon dioxide level at the second carbon dioxide monitoring inlet exceeds a carbon dioxide level at the first carbon dioxide monitoring inlet by a predetermined differential threshold. The inlets can be part of an aspirated sampling system and/or part of a distributed sensor system. Methods of monitoring carbon dioxide levels are also included.

Abstract: An analyzer and diagnostic system can include one or more sensors that are operable to generate combustion condition data relating to the performance of an associated combustion system. An analysis module can be operable to analyze at least a portion of the combustion condition data and determine a state of the associated combustion system. A diagnostic module can be operable to identify one or more recommended corrective actions for a combustion system performance deviation from a plurality of recommended corrective actions using one or more logic algorithms. Handheld instruments and methods of analyzing and diagnosing combustion processes are also included.

Abstract: Using at least one surface mount resistor as an infrared light emitter in an analytical instrument provides low cost, long life and high reliability.

Abstract: A method and system for identifying and calculating the percentages of gases, such as the automotive and other commercial refrigerant gases, in a gas mixture using infrared spectroscopy is disclosed. The novel system is compact, relatively inexpensive and has greater accuracy than those systems of the prior art.

Abstract: Method of modulating an optical light source to maintain stability with time, temperature and any variation in the source's electrical connections.

Abstract: A circuit capable of detecting natural gas at a wide range of concentrations is disclosed. The gas detection circuit includes a catalytic Wheatstone bridge circuit and an analyzing Wheatstone bridge circuit. A circuit for detecting natural gas, which includes placing a device containing the circuit described above in an area in which the air has a potential of containing natural gas, and monitoring the output signal for indications of the presence of natural gas is also disclosed.

Abstract: A portable leak detector includes a housing having an inlet and an outlet each in fluid communication between an interior and an exterior of the housing. A gas sensor, having a property that changes in response to exposure of the gas sensor to one or more gases, is positioned in fluid communication with the interior of the housing via the inlet thereof. The leak detector includes a probe lamp, a plurality of first indicator lamps supported by the housing and a speaker supported by the housing. A controller supported by the housing is connected to detect the property of the gas sensor. The controller causes the probe lamp to flash at a first frequency, causes a first group of the plurality of first indicator lamps to illuminate, and/or causes the loudspeaker to chirp at a second frequency all as a function of a detected property of the gas sensor.

Abstract: A trap for removing moisture from sampled gases includes an elongate conduit having a plug substantially positioned therein to prevent flow directly through the conduit. The conduit has a radially directed hole on each side of the plug. A tube is substantially concentric with the conduit and has end walls at opposite ends thereof adapted for the conduit to pass therethrough. At least one of the end walls has a second opening which can be stopped during sampling and unstopped for draining. During sampling, sample gases are drawn into one end of the conduit and the tube such that vapor condenses on an inner surface of the tube, entrained liquid collects on the inner surface and the gas enters the conduit on the other side of the plug and exhausts to an analyzer.

Abstract: A gas sampling apparatus includes a probe tube having a tip positionable in a stream of products of combustion and a sample dryer tube connected in fluid communication with an end of the probe tube opposite the tip. The sample dryer tube is received in a purge gas tube along a lengthwise axis thereof. The purge gas tube and the sample dryer tube define therebetween a space through which a purge gas pump urges a purge gas in a first direction. A sample pump connected in fluid communication with the sample dryer tube urges therethrough in a second direction opposite the first direction a sample of gas obtained from the stream of products of combustion via the probe tube. A sensor is positioned to detect a constituent of the sample of gas exhausted from the sample dryer tube. The sample dryer tube is formed at least in part of a hydrophilic membrane and the purge gas entering the space contains less water vapor than the sample of gas.

Abstract: A trap for removing moisture from sampled gases containing moisture in vapor and/or entrained liquid form includes an elongate conduit having a plug substantially centrally positioned therein to prevent flow directly through the conduit, the conduit being provided with a radially directed hole on each side of the plug. A tube is substantially concentric with the conduit and has stoppers at opposite ends thereof with openings therein for the conduit to pass therethrough. At least one of the stoppers is provided with a second opening which can be stopped during sampling and unstopped for draining. During sampling, sample gases are drawn into one end of the conduit and exhausted radially into the space between the conduit and the tube such that vapor condenses on the inner surface of the tube, entrained liquid collects on the inner surface and the gas enters the conduit on the other side of the plug and exhausts to an analyzer.

Abstract: A halogen gas detector comprises a coil comprising an oxidation-resistant metal wire with a nonreactive oxide coating wound into a double helix defining a cylindrical space, a conductive metal pin positioned within the cylindrical space making no contact with the coil, finely divided sintered in place sodium titanate filling the space between the coil and the pin.

Abstract: A breath gas analysis module for supplying a sample gas to a gas detector includes a manifold having a body defining a chamber therein. The chamber includes a main passage extending through the manifold body, an outlet passage extending into the manifold body from an outlet end at a base of the manifold body and toward the main passage and a metering orifice extending between and in fluid communication with the main passage and an interior end of the outlet passage. An inlet tube is attached to the manifold body at one end of the main passage and defines an internal passage in fluid communication with the main passage. A collection tube is attached to the manifold body at another end of the main passage and defines an internal passage in fluid communication with the main passage. A check valve is positioned within the inlet tube internal passage and is oriented to permit fluid flow into, but not back from, the main passage.

Abstract: A gas detector apparatus for determining the concentration of a selected one of a plurality of predetermined gases includes a gas sensor which generates a gas output signal related to the concentration of the selected predetermined gas in the gas sample. A K factor storage associated with the gas sensor stores at least one K factor, unique to and generated by using the gas sensor, for each of the plurality of predetermined gases. A processor, in response to a selected gas control signal, selects the K factor or factors from the K factor storage for the selected gas and, in accordance with a predetermined process stored therein, calculates a concentration signal representing the concentration of the selected gas in the gas sample.

Abstract: A method and product whereby color changing indicator salts such as cobaltous salts, preferably CoCl.sub.2 or CoBr.sub.2, are firmly adhered to sand, other particulate silicas or other carriers so that unwanted fines, material loss and solvent washing characteristic of prior indicator salt-coated carriers are eliminated. The process is carried out by thoroughly dehydrating a quantity of cobaltous salts and dissolving and storing the dehydrated cobaltous salt in absolute alcohol, preferably absolute ethanol. The absolute alcohol/cobaltous salt solution is then contacted onto a dehydrated or anhydrous carrier material and the absolute alcohol solvent is removed.

Abstract: An electrochemical sensor for detecting gas includes stacked reference, counter and sensing electrodes within a body and having a quantity of a liquid electrolyte in an electrolyte chamber therein. A support is provided for holding the electrodes and mats in contact with each other and at an inner end of a cavity within the sensor. A gas passage, such as a diffusion limiter, is provided through the sensor body and permits gas to reach the sensing electrode. The reference electrode is formed in a wraparound structure, with the reference electrode provided with a plurality of integral extensions which extend around the support and the counter electrode and into contact with the liquid electrolyte, thereby providing a large reference electrode fitted into a small body.

Abstract: A test kit for gas detectors is disclosed, including an aerosol can containing a predetermined gas mixture of predetermined concentration and a pierceable conduit having first and second open ends, the first open end being adapted to engage an inlet opening of the gas detector. The pierceable conduit further includes a plug having an orifice therethrough for admitting small amounts of air into an interior of the conduit. The plug is located in the conduit adjacent the second open end. A hollow needle is adapted to engage an outlet valve on the aerosol can, and the needle is manipulated to pierce the conduit, delivering the predetermined gas mixture of predetermined concentration to the gas detector.

Abstract: A temperature limited catalytic gas detector includes a catalytic gas sensor in one branch of a Wheatstone bridge network. A power supply is connected through a voltage controlled regulator to the bridge network. An instrumentation amplifier measures electrical imbalances across the bridge network. A display is connected to the output of the instrumentation amplifier. The detector also includes a comparator which compares the output of the instrumentation amplifier with a predetermined limit signal and produces an output when the output of the instrumentation amplifier exceeds the limit voyage. The regulator is responsive to the output of the comparator to thereby reduce the power supply to the bridge network. The limit signal is equivalent to the output of the instrumentation amplifier when the gas sensor is at a particular high temperature. The arrangement prevents the gas sensor from operating at excessive operation temperatures.