EMAT Thickness Gauge UT-04 EMA (Delta)
Ultrasonic Thickness Gauge UT-04 EMA (Delta) is used for measurement of thickness of items from current-conductive materials at one-sided access to them. Electromagnetic-acoustic (EМА) way of excitation and reception of ultrasonic shear oscillations is used in the Ultrasonic Thickness Gauge UT-04 EMA (Delta). The Ultrasonic Thickness Gauge UT-04 EMA (Delta) allows making measurements without contact fluid, without surfaces conditioning, through air gap or non-conducting coating (paint, varnish, enamel, film, etc.).
The Ultrasonic Thickness Gauge UT-04 EMA (Delta) can be used for measurement of thickness of sheets, vessels walls, pipes, pipelines, also of thickness of box-type, transport and other structures and products, including the ones with corroded surfaces, during their operation or after manufacturing at power producing, pipe-rolling, machine-building, ship-building, transport, repair and other enterprises.
Operation principle of the Thickness Gauge is based on pulse echo method of measurement, which uses properties of ultrasonic oscillations to be reflected from the interface between media with different acoustic resistance. Emission of ultrasonic oscillations occurs due to interaction of vortex-type currents, induced onto the surface of the tested item with EМА- transducer, while sending in a pulse of current of ultrasonic frequency, with the field of magnet of this transducer.
A pulse of ultrasonic oscillations propagates normal from the surface of the tested item, and reaches its opposite surface, than is reflected from it in the reverse direction and partly comes back to the EМА-transducer. Under action of this pulse and the magnetic field of the EМА- transducer, on the item surface there occur again, now secondary vortex-type currents, whose electromagnetic field induces in the EМА-transducer coil a series of pulses repeating with the interval
t - time of ultrasonic oscillations propagation from one surface to another and back;
d - thickness of tested material (sample);
V - speed of ultrasound propagation in material of the item.
A series of the reflected pulses is amplified, processed by the microprocessor digital circuit, and displayed for visual monitoring.
Thickness of the item is calculated with the help of microprocessor by the following formula:
and is also displayed.