Abstract: Flow measuring apparatus comprising a probe (1) coupled via a coaxial cable (2) to control circuitry with a current to voltage convertor (10), absolute value circuit (12), auto zero switch and integration (11, 27) and voltage to current circuit (18) yielding an analog output, corresponding to flow at the probe.

Abstract: The monitor is spaced a small distance from the curved path of the travelling thread to sense defects in the thread. In one embodiment, the monitoring means is spaced from the winding surface of a chuck to sense broken threads or an accurate build-up of the thread package. The monitoring means includes a detector head with a charge collector rod for sensing changes in electrical potential of the rod due to contact with a travelling thread part. The monitoring means can be moved away from the chuck to maintain a constant distance from the thread package being wound on a bobbin tube on the chuck.

Abstract: Airborne dust concentration in a silo or the like is measured by inducing flow in one or more Venturi nozzles (10) located in the area of airborne dust. A triboelectric sensor probe electrode (20) is located at the nozzle inlet section (12) and flow is induced by a feed of inductive air through an annular channel located in the wall of the nozzle downstream of the electrode.

Abstract: Apparatus for measuring the concentration of solid particles in a fluid stream wherein a critical flow orifice produces a stream of fluid having a constant velocity, a surface for effecting triboelectric charging of the particles in the gas in the constant velocity stream and a charge measuring device for measuring the charges thus triboelectrically imparted to the particles. The apparatus overcomes the inaccuracies which occur in prior art particle detectors when such particle detectors are used to monitor fluid streams whose velocity is variable e.g. air intake systems for internal combustion engines which operate at varying speeds.

Abstract: A method for measuring the purity of water in which the water is passed through an insulated pipe (1) in a cell spaced between electrodes (2-3) for measuring the tribo-electric electromotive force (e) generated by the flow, and wherein the resistivity of the water is calculated from the measured electromotive force.

Abstract: A method for monitoring characteristics of a magnetic recording head which is flying in an air bearing relationship over a rotating magnetic recording disk containing Fe.sub.2 O.sub.3 detects triboelectric charges generated by intermittent contact between the head and the disk and also detects modulations in the spacing between the head and the disk surface when the two are not in contact.

Abstract: An electrified fluid flows through a main pipe and its bypass line including a conducting pipe insulated from the remaining pipes and the main pipe. While the electrified fluid flows through the insulating pipe the latter acquires all electric charges which is, in turn, measured, as a current, by an ammeter connected between the insulated pipe and ground. A flow meter is disposed in the bypass line on the outgoing side of the insulated pipe and measures a flow rate. An electric charge density is calculated from the measured current and flow rate.

Abstract: A probe electrode is mounted across the wall of a fluidized bed column or solid particles feed thereto, and an air gap between the probe electrode and a neon lamp causes lamp flashes when the particles are normally circulating and allows the detection of stagnancy of the particles in absence of light flashes.

Abstract: A sensing device responsive to ballooning motion of textile yarns, and producing electrical sensing signals comprising a hollow or ring-shaped yarn guide body whose interior periphery is provided with motion responsive and non-responsive elements in alternate sequence.