Measurements; Measuring Process; The Hardness Value L; Measurement Accuracy - Proceq PAROTESTER 2 Operating Instructions Manual

This measured value is neither saved nor displayed.
Instead of displaying the measured value, the message
«Measure more slowly!» appears on the LCD display.
During the next correctly executed measurement, the
current hardness profile, the newly executed measure-
ment and all previously set parameters appear once
more. Also refer to section 10, «Error messages»
3

Measurements

3.1

Measuring process

The PAROTESTER measuring process is identical to the
EQUOTIP process, which is based on the energy mea-
surement principle; EQUO = energy quotient. During
testing an impact body with a steel calotte is knocked
against the test surface by spring force and then
rebounds. The impact and rebounding velocity are mea-
sured by non-contacting instruments when the calotte of the
impact body is approx. 1.5 mm away from the tested sur-
face. This is achieved by a permanent magnet integrated
into the impact body which moves through a coil during
the test and induces electrical voltages when moving
forwards and backwards which behave proportionately to
the speeds. The measured values from the impact and
rebound speeds are converted in the display device to

the hardness value L.

4 Measurements
. .
3.2 The hardness value L
This term which has been used hardness testing since
1975 is the quotient of rebound and impact speed of the
impact body multiplied by the factor 1,000.
Hardness value L = 1000 ·
Time
Impact phase Rebound phase
This hardness value comprises a 3-digit value which
increases with the hardness of the tested material.
The L-value is additionally marked with the ID letter of
the respective impact device. For example: LU = 671
for the L-value of the impact device type U.
3.3

Measurement accuracy

The measuring accuracy of the PAROTESTER (EQUO
process) when using the L-value as a direct measure-
ment gauge:
B
–
A
Fig. 1 Signal progression
during test impact
© 2012 Proceq SA