The PS 200 S or Ferroscan is a small handheld device manufactured by Hilti which can be used to locate shallow rebar and measure their diameter with mm accuracy. It can also be used, with the aid of a paper grid and a separate tablet, to produce a 2D image showing a ‘map’ of the bars.
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A Ferroscan utilises magnetic induction technology to detect ferrous objects which are buried close to the surface. It has small wheels and a simple display and works by being pushed sideways across the surface to be scanned. One coil transmits a magnetic signal and the other receives it, and by measuring variations in the magnetic field as it is passed over a buried object, a Ferroscan can detect buried metals. Using the same technology, it can estimate the diameter of a bar with a high degree of accuracy.
A Ferroscan should be able to detect the first layer of rebar in both directions – because it works by magnetic induction, it would then be blocked from further penetration. Accuracy is good, horizontal is about +/-3mm, vertical accuracy is 3mm and diameter estimation is accurate to 1mm.
A Ferroscan feels like a well-built device, it is manufactured by Hilti, a company who knows how to produce robust tools.
We tested the Ferroscan outside our office on a simple concrete slab with the first row of rebar about 10cm deep, we were particularly interested in the rebar diameter estimation feature because this is information that we are not able to recover easily using our GPR (Ground Penetrating Radar).
Unfortunately, the Ferroscan was unable to detect most of the bars (clearly visible using GPR), and when a bar could be detected the diameter estimation was wildly inaccurate.
Unfortunately the performance is so bad as to be unusable: the Ferroscan proved to be very poor at locating rebars with (any) high frequency GPR including the one made by Hilti offering a considerably better performance, and the diameter estimation feature doesn’t work. Its possible that better results would be obtained on a slab with shallower rebar, but this is not representative of a real work environment for us.
We do not recommend the PS 200 S ‘Ferroscan’.
We also tested this making very few notes as it was not a serious test at the time (on the same concrete slab) and it was equally as poor performing as a Ferroscan. We felt that on a direct comparison basis, the Ferroscan is a more serious device and more robustly constructed, but neither of them worked.
If you require a survey to detect rebars, please see our rebar location page.