Abstract: A portable refrigeration gas analyzer employs infrared spectroscopy to detect adulterant refrigerant gases in existing R12 refrigeration systems. The analyzer can detect contaminants such as R134a, R22, and butane in concentration as low as 1% by volume. A rugged opto-acoustical infrared narrow band sensor is suitable for field use in the repair of refrigeration systems.

Abstract: A circuit improvement and method leading to increased leak detection sensitivity is provided for gaseous leak detectors which utilize a hand held probe. The circuit modification provides a high pass filter and additional circuit gain which are switched together in or out of the detection circuit. When the modification is switched in circuit it is necessary to move the probe with a sweeping motion while searching for a gaseous leak.

Abstract: A spring structure for a weight scale is described which is assembled from four extruded aluminum parts. The structure readily lends itself to the addition of a platform for placing weights and its deflection resulting from a weight is essentially invariant to the location of the weight on the platform. The sensor which converts deflection of the structure into an electrical signal includes two conducting plates, attached to the structure, which constitute a variable capacitor. The variable capacitor is part of a self-excited oscillator circuit which yields a frequency which is accurately related linearly to the value of the weight. Means are provided for distorting one of the capacitor plates to provide further improvement of invariance to weight location on the platform.

Abstract: A quick-disconnect coupling engageable with a fluid fitting is disclosed. The coupling includes a body formed with a cylindrical bore. Within the bore, a valve pin is reciprocally mounted. The valve pin is biased in a closed position by a spring in combination with a threaded set screw which are positioned in the bore in axial alignment with the valve pin. The set screw is rotatable to adjustably compress the spring and adjustably bias the valve pin.

Abstract: A quartz crystal gas pressure sensor senses a range of pressures within a gaseous environment, such as from 0.1 millibar to 1 bar. The sensor includes a quartz crystal connected to manifest a piezoelectric effect upon excitation by an alternating electric field and communicating with the gaseous environment, an oscillator circuit connected to the quartz crystal for generating the alternating electric field and including a feedback circuit for providing a signal for self-excitation at the resonant frequency of the crystal as well as indication of vibrational amplitude of the crystal as a function of gas pressure within the gaseous environment, and an indicator circuit connected to the feedback circuit for converting the electrical signal into an indication of the gas pressure sensed within the gaseous environment. A gas pressure measuring method is also described.

Abstract: Method and apparatus for the determination of the fuel flow condition of a fuel injector while the fuel injector is in its operative position in an engine are described. The device comprises a liquid reservoir, a measuring chamber for the liquid and a conduit to flow the liquid through the chamber to the injector under constant pressure, as well as electric circuitry to open and close the injector for at least one predetermined time interval. The chamber is refillable from the reservoir to a predetermined liquid level after each use. The liquid can be passed through the injector in short repeated bursts or in more prolonged flows. Comparison of the volume of liquid passing through the subject fuel injector in a given time period with the volume of a like liquid passed through a reference fuel injector in the same time period is indicative of the fuel flow condition of the subject fuel injector.

Abstract: A condition tester for a storage battery that monitors the effect of internal battery resistance without drawing large currents. A switched load periodically draws a small current across the battery terminals. An AC voltage is produced at the battery terminals resulting from the oscillating current and the internal battery resistance. That small oscillating voltage is amplified, rectified and filtered to produce a DC voltage which depends upon the AC component. This DC voltage is subtracted from the nominal battery voltage and the difference is indicated by an appropriate meter. As the battery deteriorates its internal resistance increases causing the meter reading to decrease, thereby reflecting battery condition.

Abstract: A transducer coupling member for use with systems for detecting inhomogeneities in fluids flowing in a conduit. A first portion of the member is acoustically coupled to the conduit wall. An electromechanical transducer is mounted upon another portion. These two portions are partially acoustically coupled. The composite system forms a bandpass filter which eliminates frequencies and modes of oscillation which travel largely in the conduit, thus preventing the system from being rendered insensitive to inhomogeneities. The bandpass automatically adjusts to accommodate a variety of conduits.

Abstract: A method and apparatus for automatically recalibrating a leak detector. A gaseous impurities is detected by means of a corona discharge. This discharge is sampled and a signal that is a function of the corona discharge level is stored. Subsequent corona discharge levels are compared to the stored signal; and an alarm signal is produced when the subsequent discharge levels exceed the stored value by more than a predetermined amount. To recalibrate the circuit a new signal is stored representative of the corona discharge level at that time. Subsequent corona discharge levels are then compared with the newly stored signal.

Abstract: A detector comprises a pair of electromechanical transducers for disposition on a fluid-filled conduit in an acoustically coupled relationship, an adjustable gain driving amplifier responsive to the electrical output of one transducer for driving the other transducer, an automatic gain control circuit for automatically adjusting the gain of the driving amplifier maintaining the system on the margin of oscillation, and an indicating circuit for detecting modulation of the driving signal. Bubbles passing through the conduit increase the gain required to maintain the system on the margin of oscillation, and are detected as modulations of the driving signal. In a preferred embodiment, this bubble detector is utilized as a refrigerating system test instrument.

Abstract: This invention provides an apparatus for adjusting the scale and range of D'Arsonval pointer-type meters providing an uncluttered accurate readout particularly adapted for compact hand-held meters. Display wheels imprinted with numerals for a plurality of different scales are provided enabling the user to set, by manual rotation of a drive gear engaging a ring gear one of a plurality of desired ranges. The invention also provides for the simultaneous automatic selection or interconnection of circuit elements for driving the meter movement in accordance with the selected range.

Abstract: A detector comprises a pair of electromechanical transducers for disposition on a fluid-filled conduit in an acoustically coupled relationship, an adjustable gain driving amplifier responsive to the electrical output of one transducer for driving the other transducer, an automatic gain control circuit for automatically adjusting the gain of the driving amplifier maintaining the system on the margin of oscillation, and an indicating circuit for detecting modulation of the driving signal. Bubbles passing through the conduit increase the gain required to maintain the system on the margin of oscillation, and are detected as modulations of the driving signal. In a preferred embodiment, this bubble detector is utilized as a refrigerating system test instrument.