Reducing Errors When Orthogonal Sizing - Elcometer Protovale 331 Operating Instructions Manual

M
EASURING SIZE OF REINFORCEMENT BARS
significant) over-estimation of bar diameter. In particular, orthogonal sizing
should never be attempted over the crossing-point of transverse bars.
Neighbouring parallel bars, whilst not causing such drastic effects as transverse
ones, should nevertheless be taken into consideration. When the search head
is rotated to the orthogonal position, such bars will become nearer to the ends
of the search head than they were to its sides.
Welded mesh
Orthogonal sizing should not be attempted on welded mesh fabric; the
orthogonal reading will receive an additional signal from the rectangular loop of
bars. This will result in a gross over-estimate of bar-size (or even the 'SIZE
MODE ERROR' message).

9.4 Reducing errors when orthogonal sizing

This technique improves the accuracy of orthogonal sizing of bars where the
nearest parallel bars appear to be adequately distant, but the transverse bars
are closer together
the measurement position.
The technique involves zeroing the Covermeter with the search head held close
to the concrete:
j. In this situation, accuracy may also be improved by using a Narrow Pitch search head.
32
R
j
. This situation is illustrated in Figure 17 where position X is
Figure 17. Measurement position
( )
ORTHOGONAL
Transverse bars are
close together