Abstract: An electromagnetic flowmeter having a small-bore flow tube having a thick-walled plastic tube having a conically-relieved electrode-receiving bore. A compression ring around the conical part of the tube squeezes the plastic sealingly between the electrode and the ring. In assembly, compressive force exerted by Belleville springs or washers causes the plastic to flow into sealing contact with the electrode.

Abstract: A magnetic flowmeter system having a high impedance double ended AC preamplifier stage for amplifying voltages induced in a fluid flowing in and transverse to the field of an AC energized electromagnet. The preamplifier output voltages are amplified in a single-ended AC amplifier. The output voltage of the AC amplifier is demodulated by a phase sensitive detector. The DC output voltage is divided by a DC voltage derived from the AC source of energization for the electromagnet, so a net output voltage results which is free of common mode and quadrature voltages and independent of field fluctuations, but is obtained without feedback to the input of the system.

Abstract: The coils of an electromagnetic flowmeter are driven by a current waveform which is the equivalent of a composite of a sine wave and a square wave. The induced voltage is perferably sampled during steady state conditions but is at all times free of transient voltage spikes or error signals.