Abstract: A wire rope is tested simultaneously for multiple types of defects by magnetically saturating the rope at two locations in one sense and at an intermediate location in an opposite sense. A sensing coil at any of these locations detects cross sectional area variations in the rope. Two sensing coils positioned respectively between each pair of adjacent locations defect contact pattern variations in the rope. Broken wires are detected by two coils located respectively on opposing sides of the intermediate location and spaced apart by a distance which equals the radius of the coils.

Abstract: A method and apparatus is provided for electromagnetically testing an elongate object such as a wire rope for cross-sectional area variations. The elongate object is magnetized over adjacent sections in opposing directions along a longitudinal axis of the elongate object. Variations in axial magnetic flux, which have been observed to be coincident with variations in the cross-sectional area of an elongate object, are measured by a plurality of non-inductive transducers. The transducers are interconnected to produce a composite signal. The composite signal is compared to a reference signal.

Abstract: A wire rope tester which can detect broken wires, area reductions, or wire contact irregularities. The tester includes two permanent magnetic stacks which produce axial adjacent and opposed DC magnetic fields which magnetize the rope. Broken wires are indicated by flux variations when the flux density is at saturation; area reductions are related to flux variations; also at saturation flux density; and wire contact pattern changes produce detachable eddy current flux variations when the flux density gradient is constant.

Abstract: A carbon monoxide gas detector comprises a housing consisting of two enclosures 10 and 12 having ports in the wall thereof to provide a tortuous path for air entering the inner enclosure 12. A gas cell transducer 16 connected to an electrical circuit 18 provides signals indicative of gas concentration. The detector is powered from a remote supply via wires 22 and 26 and provides gas concentration signals via a wire 24 to a remote central station with a fail-safe feature wherein failure of the circuit or the detector will provide signals interpreted as dangerous gas concentrations.

Abstract: An alarm system which includes at least one primary detecting device that provides an analog output signal. The rate of change of the analog output signal is monitored, and an alarm signal is generated when the rate of change exceeds a preset limit. The analog output signal is also compared with a first reference level signal to provide a pre-maintenance warning signal when the analog output signal reaches the first reference level.

Abstract: A single chamber ionization-type fire detector. The ionization current is directly amplified to provide a usable analogue signal by means of an operational amplifier which has a minimal effect in the ionization current. The operational amplifier is simultaneously employed to maintain a constant potential difference in the chamber so that the ionization current is not subjected to a fluctuating voltage. The amplified analogue signal drives a recorder and through analysis of the recorder output genuine fire alarm conditions can be distinguished from false alarm conditions.