Abstract: An apparatus comprising one or more pairs of analyzers measures light absorbing particulates, including black, brown, and ultraviolet light absorbing organic aerosols, suspended in gaseous samples, such as air. One analyzer receives an ambient gas sample, while the other analyzer is coupled to a dilution inlet that mixes ambient gas with a proportion of clean gas, whereby the two received samples have different particulate concentrations. Filters with identical filter areas accumulate particulates as the respective samples flow through with equal flow rate and velocity. An optical source and detector for each filter measures a changing property (e.g. attenuation at one or more wavelengths) as particulates accumulate. A computer uses the differential particulate accumulation from the ambient and diluted samples to compensate for filter loading effects upon the measurement to provide an accurate indication of particulate concentration in the ambient sample.

Abstract: A sequential air sampler is provided having a rotatable carrier adapted to support filter cassettes received from a supply magazine at a load station, transport them to a sampling station where gas flow is directed through that cassette, and then be transported to an unload station to be received by a storage magazine. A Geneva driver operated by a single motor provides intermittent rotation to the carrier between fixed positions. A cam rotates in concert with the Geneva driver so that a follower in reciprocating motion pushes up and then pulls down a pair of plungers for simultaneous cassette loading and unloading whenever the carrier is at one of its fixed positions. Magazines have magnetically actuated stoppers to keep the stack of cassettes in place until released. Magazines may also have a retaining lid with a position-adjustable piston to secure cassettes for transport.

Abstract: An apparatus comprising one or more pairs of analyzers measures light absorbing particulates, including black, brown, and ultraviolet light absorbing organic aerosols, suspended in gaseous samples, such as air. One analyzer receives an ambient gas sample, while the other analyzer is coupled to a dilution inlet that mixes ambient gas with a proportion of clean gas, whereby the two received samples have different particulate concentrations. Filters with identical filter areas accumulate particulates as the respective samples flow through with equal flow rate and velocity. An optical source and detector for each filter measures a changing property (e.g. attenuation at one or more wavelengths) as particulates accumulate. A computer uses the differential particulate accumulation from the ambient and diluted samples to compensate for filter loading effects upon the measurement to provide an accurate indication of particulate concentration in the ambient sample.

Abstract: A sequential air sampler is provided having a rotatable carrier adapted to support filter cassettes received from a supply magazine at a load station, transport them to a sampling station where gas flow is directed through that cassette, and then be transported to an unload station to be received by a storage magazine. A Geneva driver operated by a single motor provides intermittent rotation to the carrier between fixed positions. A cam rotates in concert with the Geneva driver so that a follower in reciprocating motion pushes up and then pulls down a pair of plungers for simultaneous cassette loading and unloading whenever the carrier is at one of its fixed positions. Magazines have magnetically actuated stoppers to keep the stack of cassettes in place until released. Magazines may also have a retaining lid with a position-adjustable piston to secure cassettes for transport.

Abstract: A pulsation and particle suppressing continuous air flow system for air sampling instruments, particularly particle counters. An air pump occupies a portion of a sealed vacuum housing, with the other portion of the housing forming a surge chamber used to damp surges as the air pump attempts to pump air towards an air outflow port through an outflow pipe. The unoccupied volume of the surge chamber dampens or dilutes the surges at an air inflow port of the housing that is associated with an air sampling instrument, such as a particle counter. The air outflow port is associated with a filter for trapping particles originating inside of the air pump and associated motor while the interior of the housing itself traps particles originating outside of the air pump and motor.

Abstract: A particulate mass measuring device of the beta attenuation type featuring a sheath air plenum from which a radial sheath airflow pathway extends which is in fluid communication with an ambient air chamber. The radial sheath airflow from the radial sheath airflow pathway merges with an axial ambient airflow from the ambient air chamber deflecting particulate matter from surfaces of the ambient air chamber thereby increasing the accuracy of particulate mass measurements. The radial sheath airflow is particle free or substantially particle free. In other embodiments, the radial sheath airflow is used to deflect particulate matter in other particulate mass measuring devices, such as those that measure particulate mass in liquid and gas samples.

Abstract: A particulate mass measuring device of the beta attenuation type featuring a sheath air plenum from which a radial sheath airflow pathway extends which is in fluid communication with an ambient air chamber. The radial sheath airflow from the radial sheath airflow pathway merges with an axial ambient airflow from the ambient air chamber deflecting particulate matter from surfaces of the ambient air chamber thereby increasing the accuracy of particulate mass measurements. The radial sheath airflow is particle free or substantially particle free. In other embodiments, the radial sheath airflow is used to deflect particulate matter in other particulate mass measuring devices, such as those that measure particulate mass in liquid and gas samples.

Abstract: A rotational cup anemometer with an improved design for the cups is herein disclosed. The anemometer has a rotational assembly with essentially identical cups. Each cup is asymmetric to the plane of rotation. Each cup has a central axis parallel to the plane of rotation. Each cup is asymmetric to the central axis of the cup. Each cup may have a lower surface extension that provides a lifting surface, contributes to an upward force as the rotational assembly is rotated or affects presented frontal area at wind angles. A rotation rate of the rotational assembly as a function of wind angle is closer to the ideal cosine curve as compared to a standard anemometer, for a range of wind angles. Rotating the rotational assembly in a wind parallel to the plane of rotation produces a net upward force on the cups that offsets the weight of the rotational assembly.

Abstract: A rotational cup anemometer with an improved design for the cups is herein disclosed. The anemometer has a rotational assembly with essentially identical cups. Each cup is asymmetric to the plane of rotation. Each cup has a central axis parallel to the plane of rotation. Each cup is asymmetric to the central axis of the cup. Each cup may have a lower surface extension that provides a lifting surface, contributes to an upward force as the rotational assembly is rotated or affects presented frontal area at wind angles. A rotation rate of the rotational assembly as a function of wind angle is closer to the ideal cosine curve as compared to a standard anemometer, for a range of wind angles. Rotating the rotational assembly in a wind parallel to the plane of rotation produces a net upward force on the cups that offsets the weight of the rotational assembly.

Abstract: A nephelometer for detecting the concentration of particulates in a sample aerosol is provided with a branched flow path with a sample aerosol input, a clean gas input and an output leading to an optical sensor unit. At least one of the inputs has periodic variable flow so that a concentration-modulated gas stream is supplied to the optical sensor unit. The detector output of the sensor unit is processed in synchrony with the concentration modulation to filter out DC components, such as 1/f noise and parasitic instrument noise.

Abstract: A nephelometer for detecting the concentration of particulates in a sample aerosol is provided with a branched flow path with a sample aerosol input, a clean gas input and an output leading to an optical sensor unit. At least one of the inputs has periodic variable flow so that a concentration-modulated gas stream is supplied to the optical sensor unit. The detector output of the sensor unit is processed in synchrony with the concentration modulation to filter out DC components, such as 1/f noise and parasitic instrument noise.

Abstract: A radiation detector of the present invention has at least one radiation measuring component and a radiation detector surface. A layer of protective covering substantially covers the radiation detector surface and protects the at least one radiation measuring component. The layer of protective covering preferably includes a protective material sub-layer and may include an optional coating sub-layer. The radiation detector surface may be, for example, a scintillator, cover glass, or chip surface.