Abstract: Apparatus for determining flowability of a powder by sensing powder avalanching includes a sample drum having a generally cylindrical sample chamber for holding a powder sample, a support frame including a drum shaft for supporting the sample drum for rotation, a drive motor and a drive mechanism coupled between the drive motor and the drum shaft such that the drum rotates when the drive motor is energized. The apparatus further includes an avalanche sensor for sensing avalanching of the powder sample within the sample chamber as the sample drum rotates. The avalanche sensor may be implemented as a backlash sensor for sensing intermittent reverse angular displacement of the sample drum caused by avalanching of the powder sample. A torque loading sensor may also be used to sense avalanching of the powder sample. A controlled gas may be circulated through the sample chamber by a gas conditioning system. The gas in the sample chamber can be measured and/or controlled.

Abstract: A handheld therapeutic material delivery system includes a droplet dispersion chamber, a droplet generating assembly for generating droplets of a fluid containing the therapeutic material and for supplying the droplets to the dispersion chamber, and a gas conditioning assembly for supplying heated gas to the dispersion chamber to form a heated transport gas stream. The droplets are dispersed in the heated transport gas stream in the dispersion chamber to provide an aerosol stream containing the droplets. The aerosol stream is supplied to the patient in response to a negative pressure applied by the patient. The delivery system may include a droplet inspection assembly for determining a characteristic of the aerosol stream and a feedback unit responsive to the determined characteristic of the aerosol stream for controlling one or both of the droplet generating assembly and the gas conditioning assembly.

Abstract: A system and process for respirator fit-testing are disclosed. The system includes conduits for taking first and second aerosol samples, from inside of the respirator mask and from outside of the mask, respectively. The samples are provided to a radial differential mobility analyzer for generating first and second modified samples corresponding to the aerosol samples. The modified samples are provided to a condensation particle counter, which generates first and second concentration values representing concentrations of suspended elements in the respective modified samples. Comparison of the concentration values yields a fit factor indicating how effectively the respirator seals against leaks. Alternative embodiment systems employ a cylindrical DMA, an electrical precipitator, or an inertial separating device in lieu of the radial DMA. For generating concentration values, an electrometer, a photometer or an optical particle counter can be used in lieu of the condensation particle counter.

Abstract: Apparatus for determining flowability of a powder by sensing powder avalanching includes a sample drum having a generally cylindrical sample chamber for holding a powder sample, a support frame including a drum shaft for supporting the sample drum for rotation, a drive motor and a drive mechanism coupled between the drive motor and the drum shaft such that the drum rotates when the drive motor is energized. The apparatus further includes an avalanche sensor for sensing avalanching of the powder sample within the sample chamber as the sample drum rotates. The avalanche sensor may be implemented as a backlash sensor for sensing intermittent reverse angular displacement of the sample drum caused by avalanching of the powder sample. A torque loading sensor may also be used to sense avalanching of the powder sample. A controlled gas may be circulated through the sample chamber by a gas conditioning system. The gas in the sample chamber can be measured and/or controlled.

Abstract: An apparatus for non-contact measurement of particles, fibers and other light scattering elements includes two laser beams that intersect one another to form a measuring region within a composite flow. Particles in the flow scatter the laser energy as they traverse the measuring region. Scattered energy is received by a pair of optical detectors that generate respective electrical signals based on received energy. The detectors have selectively contoured non-rectangular apertures to controllably vary transmittance and as a result generate phase differences according to a corresponding non-linear function that relates the phase differences to particle diameters. One particularly effective aperture shape includes opposite sides contoured according to a lognormal function, to resemble an onion or tear drop. Triangular and trapezoidal apertures also can be used to achieve non-linear functions.

Abstract: An aerodynamic particle size measuring device includes a laser energy source and beam splitting, shaping and polarizing optics for forming two parallel, peripherally overlapping beams. The beams are caused to intersect a gas stream perpendicular to the direction of gas flow, thus to form a measuring volume at the intersection of the beams and flow. Single particles are carried through the measuring volume with the gas flow, each particle scattering and extinguishing light according to the beam profile, as predetermined by the degree of beam overlap and the Gaussian intensity distribution of each beam. A photodetector, responsive either to scattered light or light extinction, generates a time-dependent voltage profile that tends to replicate the intensity profile. The resulting electrical signal is processed to determine an amplitude, set a threshold for minimally acceptable amplitudes, and to derive two negative-going zero crossings for an unambiguous time/velocity determination.

Abstract: An interferometric system for measuring cross-sectional dimensions of glass fibers and other elongate objects includes: a transmitting optics module for generating two laser beams, and causing the laser beams to intersect and interfere with one another over a measuring volume; several photodetectors to collect the light scattered by the glass fiber positioned in the interference region; and signal processing circuitry to deduce the fiber diameter using phase shifts between the signal pairs and fiber velocity using the frequency of the signals. The system further offers: elimination of the 360.degree.

Abstract: A system for measuring cross sectional diameters of optical fibers and other elongate cylindrical objects includes a transmitting optics module for generating two collimated laser beams, and causing the beams to intersect and interfere with one another over a measurement region. The optical fiber under inspection is caused to intersect the measurement region with its longitudinal axis perpendicular to a plane defined by the laser beams. Several photodetectors collect light scattered by the optical fiber, and generate signals indicating fiber diameter based on phase differences in the scattered light received by the detectors. The system can determine fiber refractive index by using three detectors to obtain two phase shifts. Differences in Doppler frequencies also are sensed by the detectors, for determining transverse velocity components.

Abstract: A system for measuring cross sectional diameters of optical fibers and other elongate cylindrical objects includes a transmitting optics module for generating two collimated laser beams, and causing the beams to intersect and interfere with one another over a measurement region. The optical fiber under inspection is caused to intersect the measurement region with its longitudinal axis perpendicular to a plane defined by the laser beams. Several photodetectors collect light scattered by the optical fiber, and generate signals indicating fiber diameter based on phase differences in the scattered light received by the detectors. Differences in Doppler frequencies also are sensed by the detectors, for determining transverse velocity components.

Abstract: The concentration of non-volatile residue in a test solvent is determined by generating multiple liquid droplets from a liquid stream including the solvent and ultrapure water. The droplets are dried to form a stream of multiple particles of the non-volatile residue. A supply of ultrapure deionized water is caused to flow continuously toward a non-volatile residue monitor, at a constant fluid flow rate. Upstream of the residue monitor, a syringe is provided for intermittently injecting a test solvent into the fluid stream. In one case, the solvent is injected for several minutes at a constant flow rate substantially less than that of the ultrapure water. A mixing valve, downstream of the point of solvent introduction, causes turbulent flow to thoroughly mix the solvent and water. In an alternative approach, a syringe is used to instantaneously inject solvent in the form of bursts.

Abstract: A system for determining the fractional capture efficiency of filters includes two filters having substantially the same capture efficiency connected in series. A steady, controlled flow of ultrapure water and a colloidal silica suspension is directed through both filters, with respective stages of the flow upstream of the upstream filter, between the filters and downstream of the downstream filter, directed to respective non-volatile residue monitors. Each residue monitor produces a digital output representing the non-volatile residue concentration at its respective stage. A microprocessor receives the digital outputs and generates respective residue values indicating residue concentration in parts per billion. The three residue values are used to characterize the residue by proportion of the colloidal silica suspension to other residue components, and to calculate filter capture efficiency with respect to the colloidal silica.

Abstract: An ultrasonic anemometer employs three ultrasonic transducers arranged in a configuration defining a horizontal equilateral triangle. Each of the transducers has a response profile characterized by a primary central lobe and secondary or side lobes angularly inclined from and surrounding the primary lobe. Each transducer is tilted from the horizontal to align the secondary lobes with signal propagation paths between it and the other transducers, thus affording a minimum number of transducers performing at a high degree of efficiency. Circuitry is employed to cause the ultrasonic transducers to generate either continuous wave acoustic signals or single pulse acoustic signals on an alternating basis. In each case only one of the transducers transmits the acoustic signal while the other two transducers receive the signal.

Abstract: A vacuum particle detector includes a cavity providing a passage for fluid flow, a laser diode and beam shaping optics to form a substantially rectangular beam spanning the chamber. Light sensing optics, including a pair of biconvex lenses, receive light scattered when the particles suspended in the fluid intersect the beam. At least some of the scattered light is transmitted through the lenses to a photodetector. The photodetector width is selected in concert with the focal lengths of the biconvex lenses, to provide a viewing depth of field commensurate with the complete span of the beam across the chamber, whereby the photodetector responds to particles that intersect the beam over the entire span. A cone and a surrounding sleeve, both concentric about an axis of the beam, absorb the laser energy beam to provide an effective beam stop.

Abstract: An electrospray nebulizer generates an aerosol comprised of submicrometer droplets substantially uniform in size. A liquid sample is supplied at a controlled rate to a capillary needle of the nebulizer, and droplets are formed due to an electrical field in the region about the needle discharge. The tendency of the droplets to disintegrate due to Coulomb forces is counteracted by sources of ionizing radiation within the nebulizer. The ions reduce the charge in each droplet while solvent evaporation reduces the diameter of the droplet. To further ensure against Coulomb disintegration, a controlled air sheath is introduced to the nebulizer for transporting droplets more rapidly downstream. Optionally, solvent vapor can be introduced into the air flow to reduce the rate of solvent evaporation within the nebulizer, and ions can be added to the air flow upstream of the needle discharge.

Abstract: A particle flux counter apparatus utilizing light extinction. The apparatus utilizes two oppositely disposed cylindrical mirrors (21a, 21b) to bounce a beam back and forth between them, the beam traversing the length of the cylindrical mirrors (21a, 21b) in incremental steps. A plane mirror (22) is cooperatively located to reflect the beam back between the system to traverse the length of the cylindrical mirrors (21a, 21b) a second time in incremented steps. The two sets of steps interleaving such that the beam forms a sheet of light. A detector (60) monitors the intensity of the beam. As particles in a sample aerosol intersect the beam, the light is extinguished and the beam intensity changes. The detector (60) transmits a signal to a microprocessor (108) analyzation. The apparatus also utilizes a feedback circuit (300) to regulate the beam intensity and alternatively provides for modulating the beam to provide for higher peak power into the detector (60) and elimination of common mode noise.

Abstract: A continuous flow condensation particle counter employs a working fluid to saturate a gas stream, and then condense onto particles carried in the gas stream as the stream is directed through a condenser and cooled below the supersaturation point. A porous saturation block is positioned beneath the condenser, and receives droplets of working fluid condensate and water as the droplets descend from the condenser by gravity. The saturation block is constructed of a hydrophobic material, whereby it allows the working fluid to pass through but retains water within a collection reservoir centered below the condenser. A vacuum pump and a periodically actuated solenoid valve are employed to introduce a partial vacuum to the reservoir and thereby evacuate accumulated water. The preferred working fluid is a perfluorinated hydrocarbon fluid that is substantially odorless, chemically inert and non-flammable. Water is immiscible in the working fluid, and thus readily separable.

Abstract: An apparatus for measuring nonvolatile residue concentrations in liquid is disclosed. A plurality of fixed and adjustable flow restrictive elements are utilized and arranged in-line from a fluid supply source to provide a constant, pressure controlled flow of liquid to the measuring apparatus and allow for real-time measurements and optimal concentration detection. An atomizer atomizes the liquid into droplets which are dried to nonvolatile residue particles. The nonvolatile residue particle concentration is then determined utilizing an electrostatic aerosol detector. The invention further discloses apparatus for collecting a sample of nonvolatile residue for analysis and identification using a corona precipitator.

Abstract: A non-imaging particle counter 10 utilizing one or more detectors 25 which directly collect light scattered by particles in a fluid traversing a sensing volume 63. The detectors 25, are non-imaging, non-focusing, optic-less light collection devices, such as large area photodiodes. The detectors 25 are arranged and configured proximate the sensing volume 63, but such that the beam of light 60 is not operatively incident thereon. The beam of light 60 is provided by a laser 50 and is shaped by a focusing/collimating lens 54. The beam of light 60 passes through several apertures 51-53 to reduce stray/background light in the system. The detectors 25 are oriented at an angle with respect to the plane formed by the longitudinal axis of the beam and the flow of fluid, wherein stray light 61 strikes the detectors 25 at an angle greater than the acceptance angle of the detectors 25, while scattered light strikes the detectors 25 at an angle less than the detectors' 25 acceptance angle.

Abstract: An instrument for detecting single airborne particles, and measuring their concentration, includes a transmitting optical fiber optically connected to a light source at one end, and a collecting optical fiber connected to a photodiode at one of its ends. The respective opposite ends of the optical fibers are potted into a rigid probe head with their exposed ends polished smooth and flat, facing each other and separated by an air gap of about one-tenth of an inch. At least some of the light from the source crosses the gap between the optical fibers and reaches the detector, such portion of the light defining a particle sensing volume. Particles passing through this volume are detected by optical extinction as they reduce the amount of light reaching the detector. The device has simple optics, requiring no lenses or mirrors. The transmitting and collecting fibers, and the air gap, form a well defined and repeatable sensing volume so that individual devie calibration is not required.

Abstract: An apparatus and method for determining the concentration of macromolecules and colloids in a liquid sample is disclosed. The apparatus preferably includes an electrospray apparatus 16 for forming droplets from the sample. Liquid is removed from the droplets by drying in the electrospray apparatus 16, thereby forming an aerosol. The aerosol of a size greater than a predetermined size is then counted by a condensation nucleus counter 52. In this manner, the target macromolecules and colloids are counted. This apparatus is capable of detecting very small macromolecules and colloids of a wide range of materials in a liquid, for example, individual molecules having molecular weight as small as 10,000.