EMA Thickness gauge EM4000. User Manual
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PURPOSE OF THE DEVICE
Electromagnetic–acoustic thickness gauge EM4000 (hereinafter referred to as
the device) is designed to measure the wall thickness of steel pipes, sheet metal, rods
and other products made of steel, as well as aluminium and other metals, without the
use of couplant and without preliminary surface preparation, with a working a gap
between the sensor and metal up to 3 mm. The gap can be a layer of rust, a layer of salt
deposits or other non-conductive coating (paint, varnish, enamel, plastic etc.). The
device also allows you to measure the thickness of non-conductive coatings such as
paint, varnish, enamel, plastic etc. in the range from 0 to 5 mm.
WORKING PRINCIPLE
The operation of the device is based on two physical methods. The ultrasonic
method is used to measure the thickness of a metal sample. The eddy current method
is used to measure the thickness of non-conductive coatings.
The ultrasonic method for measuring thickness is based on measuring the transit
time of an acoustic wave through the material of the test sample. The measured time is
converted into thickness using the specified value for the propagation speed of the
ultrasonic wave. In this case, for the formation of an acoustic wave, the device uses an
electromagnetic–acoustic conversion, due to which the formation of a wave occurs
directly on the surface of the test sample, bypassing the contact medium between the
converter and the sample. Thanks to this, there is no distortion of the wave in this
environment.
The eddy current method for measuring the thickness of non-conductive coatings
is based on measuring the amplitude of the field of eddy currents that are formed near
the surface of the test sample due to the emitting coil located in the sensor of the device.
