The Elcometer NDT CG20 Corrosion Ultrasonic Thickness Gauge (part number CG20) is a fixed velocity handheld ultrasonic gauge that measures the remaining thickness of metal and plastic materials without cutting into them. This product has been discontinued; contact BAMR for a recommended replacement model.

Corrosion and wear thin the walls of pipes, tanks and components from the inside, where the loss is hidden until a section becomes dangerously thin. The CG20 sends an ultrasonic pulse into the material and times the returning echo to calculate thickness, allowing inspectors to monitor metal loss before a wall fails. It holds two user-programmable velocities plus 8 pre-programmed velocities for aluminium, steel, stainless steel, cast iron, plexiglass, PVC, polystyrene and polyurethane, which suits anyone who tests several different materials regularly. The unit is small, lightweight and water resistant, and built for harsh environments.

The gauge operates in Pulse-Echo mode at 4 readings per second over a measuring range of 0.63 to 500mm, with accuracy of plus or minus 0.01mm and resolution of 0.01mm. The velocity calibration range is 1250 to 10,000m/s. It uses a dual element transducer with a 1 to 10MHz frequency range, automatic V-path correction and manual probe zeroing. The aluminium case has gasket-sealed end caps and a waterproof membrane keypad, runs up to 200 hours on 2 AA batteries and resists impact, water, dust and petroleum products. The CG20 was supplied by BAMR, South Africa's authorised Elcometer distributor.