Abstract: A particle concentration analyzing system for testing particle concentrations in a fluid sample, such as engine emission particle concentration present in the exhaust of an engine. The particle concentration analyzing system includes a condensation particle counter having a saturation chamber, a condenser, and a laser optic particle counter. The analyzing system further includes a working fluid tank, a working fluid pump, and a sampling probe. The system provides a robust analysis system for a user to test vehicle emissions without being highly trained on the device, as the device is protected from misuse. A position sensitive sensor is used to ensure that the system is not damaged if the system is tipped over or placed in a position that would produce false results. Additional features include differential pressure sensors, a sealed and replaceable tamper resistant working fluid tank, a solvent recovery system, an anti-cheat device, and fluid purity sensors.

Abstract: A particle concentration analyzing system for testing particle concentrations in a fluid sample, such as engine emission particle concentration present in the exhaust of an engine. The particle concentration analyzing system includes a condensation particle counter having a saturation chamber, a condenser, and a laser optic particle counter. The analyzing system further includes a working fluid tank, a working fluid pump, and a sampling probe. The system provides a robust analysis system for a user to test vehicle emissions without being highly trained on the device, as the device is protected from misuse. A position sensitive sensor is used to ensure that the system is not damaged if the system is tipped over or placed in a position that would produce false results. Additional features include differential pressure sensors, a sealed and replaceable tamper resistant working fluid tank, a solvent recovery system, an anti-cheat device, and fluid purity sensors.

Abstract: An engine exhaust flow meter and method of measuring engine exhaust flow rate includes a flow tube and a differential pressure meter that is adapted to measure differential pressure in exhaust flow through the flow tube. A computer samples the differential pressure meter at a rate that is greater than the pulsation of exhaust flow to obtain a differential pressure signal. The computer is responsive to the differential pressure signal to compute a mean differential pressure value. The computer is responsive to the differential pressure signal to compute a mean magnitude of pressure pulses. The computer determines a compensation factor as a function of the mean magnitude of pressure pulses and adjusts the mean differential pressure value as a function of the compensation factor to obtain an engine exhaust flow value that is flow pulsation compensated.

Abstract: An engine exhaust flow meter and method of measuring engine exhaust flow rate includes a flow tube and a differential pressure meter that is adapted to measure differential pressure in exhaust flow through the flow tube. A computer samples the differential pressure meter at a rate that is greater than the pulsation of exhaust flow to obtain a differential pressure signal. The computer is responsive to the differential pressure signal to compute a mean differential pressure value. The computer is responsive to the differential pressure signal to compute a mean magnitude of pressure pulses. The computer determines a compensation factor as a function of the mean magnitude of pressure pulses and adjusts the mean differential pressure value as a function of the compensation factor to obtain an engine exhaust flow value that is flow pulsation compensated.

Abstract: A calibration method for a flow measuring device used with a vehicle exhaust analysis system includes the flow measuring device being connected with the vehicle exhaust system wherein exhaust gases are directed through the flow measuring device. A portable flow calibration device is connected in a manner that exhaust gases of the vehicle exhaust system are directed through the portable flow calibration device. The vehicle is operated so that exhaust gas flows through the flow measuring device and the flow calibration device. The flow measuring device is calibrated with the portable flow calibration device. The flow measuring device includes a Pitot tube assembly in a flow tube wherein gas flowing through the flow tube passes the Pitot tube assembly. The Pitot tube assembly includes a sensing tube and at least one pressure sensing port connected with the sensing tube. The sensing tube includes a plurality of sensing openings that are positioned at different portions of gas flowing through the flow tube.

Abstract: A method and apparatus for proportional sampling of particulate material present in the exhaust gas emitted from an engine, in order to measure the mass of particulate material present in the exhaust gas, utilizes a mixing chamber (18) for mixing a portion of the exhaust gas with a dilution gas. A flow control (20) controls the flow rate of the portion of the exhaust gas as a function of exhaust gas flow by activating individual ones of a parallel array of solenoid valves (30), each defining a flow restriction (34).

Abstract: A method and apparatus for proportional sampling of particulate material present in the exhaust gas emitted from an engine, in order to measure the mass of particulate material present in the exhaust gas, utilizes a mixing chamber (18) for mixing a portion of the exhaust gas with a dilution gas. A flow control (20) controls the flow rate of the portion of the exhaust gas as a function of exhaust gas flow by activating individual ones of a parallel array of solenoid valves (30), each defining a flow restriction (34).

Abstract: There is provided apparatus for the measurement of particle mass concentration of an aerosol and which comprises at least one aerosol inlet and at least one electrostatic precipitator which directs an aerosol flow towards a mass sensor on which the particles are collected, the sensor being housed in a magazine including a plurality of other sensors, each of which may be substituted for the sensor, and a control. The control selectively connects one of the at least one aerosol inlet with one of the sensors.

Abstract: An apparatus and method for the analysis of particles in an aerosol includes providing an inlet for the aerosol, a sample collector which accumulates particles passing through the inlet, a sample conditioning system which can vary at least one condition relating to the collected sample, a controller which causes the sample conditioning system to operate at select conditions, a measuring device for determining at least one parameter relating to the accumulated particles. The controller monitors the parameter while the condition is varied.

Abstract: An aerosol generator (10) includes a plate (18) defining an orifice (20) through which a jet of liquid is projected, which breaks up into droplets. The plate (18) is vibrated to control the droplet size, and the size distribution. The droplet size distribution is monitored, and this information is used to control the vibration to ensure the droplets are monodisperse and of the correct size. This can be achieved as follows: the droplets are diverted by a transverse air stream, and an optical image is obtained of the diverted jet (28) onto a linear array of photodetectors (34). The signals from the photodetectors represent the particle size distribution, and are supplied as input to a computer (36) whose output is used to control the vibration of the plate (18).

Abstract: An aerosol sampler comprises at least one U-tube whose ends are fixed to a support, and through which the aerosol is caused to flow. Means are provided to set the tube vibrating, and to measure its resonant frequency. The bend of the U-tube acts as an impactor so aerosol particles larger than a cut-off size are trapped, causing a change in the measured frequency. A sampler may include a number of such U-tubes in series, with steadily decreasing cut-off sizes, so the aerosol particulate size distribution can be determined.

Abstract: An enclosure for a pocket calculator can be mounted on the user's forearm or mounted at a 45.degree. angle to a desktop. This dual positioning of the calculator is achieved by a pad positioned between the enclosure and the user's forearm when the enclosure is mounted on the forearm. When it is desired to mount the calculator on a desktop, the pad may be partly folded to form a prop for propping the upper side of the calculator above the desktop. The enclosure has a transparent window above the keys of the calculator made of a plastic vinyl material so highly flexible that the user can depress any selected key with his finger without depressing any other key.