Preparing For Measurement - Bosch GTC 400 C Professional Manual Original

OBJ_BUCH-3136-002.book Page 20 Tuesday, August 22, 2017 6:26 PM
20 | English
In the "Settings" menu, you can choose whether and after how
much time the measuring tool automatically switches off (see
"Switch-off time", page 22).
If the battery or the measuring tool is not within the operating
temperature range stated in the Technical Data, the measur-
ing tool will shut down automatically after a brief warning (see
"Troubleshooting – Causes and Corrective Measures",
page 23). Allow the measuring tool to reach to the correct
temperature and then switch it back on.
To save energy, only switch the measuring tool on when you
are using it.

Preparing for Measurement

Setting the Emissivity Degree for Surface-temperature
Measurements
The emissivity degree of an object depends on the material
and the structure of its surface. It indicates whether an object
(in comparison with other objects with the same tempera-
ture) emits much or little infrared heat radiation.
To determine the surface temperature, the tool performs a
contactless measurement of the natural infrared thermal radi-
ation emitted by the object at which the tool is aimed. To en-
sure correct measurement, the emissivity setting on the
measuring tool must be checked before every measure-
ment and adapted to the measuring object if necessary.
You can select one of the preset emissivity levels or enter an
exact numerical value. Adjust the required emissivity using
the "Measurement" >"Emissivity" menu (see page 21).
 Temperature measurements will only be correct if the
emissivity setting and the emissivity of the object
match.
Differences in colour may be caused by different tempera-
tures and/or different emissivity levels. If the emissivity levels
are very different, the depicted temperature differences may
differ considerably from the actual temperature differences.
If there are multiple objects made of different materials or
that have different structures in the measurement range, the
displayed temperature values are only conclusive for the ob-
jects that match the emissivity setting. For all other objects
(with different emissivity levels), the displayed colour differ-
ences can be used as an indication of temperature relation-
ships.
Material
(reference value 0 °Cto100 °C)
Concrete
Plaster/mortar
Roofing tiles
Roofing felt
Radiator paint
Wood
Linoleum
Paper
1 609 92A 3RD | (22.8.17)
Notes on the Measuring Conditions
Highly reflective or shiny surfaces (e.g. shiny tiles or polished
metals) may distort or impair the results shown. If necessary,
mask the surface to be measured with a dark, matt adhesive
tape that conducts heat well. Allow the tape to acclimatise
briefly on the surface.
Make sure that a favourable measuring angle is used on reflec-
tive surfaces in order to ensure that the thermal radiation re-
flected by other objects does not distort the result. For exam-
ple, the reflection of your own body heat may interfere with the
measurement when measuring head-on from a perpendicular
position. On a level surface, the outline and temperature of your
body could therefore be displayed (reflected value), and these
values do not correspond to the actual temperature of the
measured surface (emitted value or real value of the surface).
Measuring through transparent materials (e.g. glass or trans-
parent plastics) is fundamentally not possible.
The accuracy and reliability of the measuring results increase
with better and more stable measuring conditions.
Infrared temperature measurement is impaired by smoke, va-
pour/high air humidity or dusty air.
Information for achieving improved measurement accuracy:
– Get as close as possible to the measuring object to mini-
mise interfering factors between you and the surface to be
measured.
– Ventilate indoor areas prior to measurement, especially
when the air is contaminated or extremely steamy.
After ventilating, allow the room to acclimatize for a while
until the usual temperature has been reached again.
Assigning temperatures on the basis of the scale
A scale is shown on the right-hand side of the dis-
play. The values at the top and bottom end are ori-
ented to the maximum and minimum temperature
recorded in the thermal image. Colours are as-
signed to temperature values with a uniform distri-
bution in the image (linearly).
Different shades can therefore be used to assign
temperatures within these two limit values. For ex-
ample, a temperature that is exactly between the
maximum and minimum value can be assigned to
the centre colour range of the scale.
To determine the temperature of a specific area,
move the measuring tool so that the crosshairs
with temperature display l are aimed at the re-
Emissivity
quired point or area.
In the automatic setting, the colour spectrum of
0.93
the scale is always distributed linearly (= uniformly) across
0.93
the entire measurement range between the maximum and
0.93
minimum temperatures.
0.93
The thermal imaging camera displays all measured tempera-
0.93
tures in the measurement range in relation to one another. If
heat is displayed as blue in the colour palette in an area, for
0.91
example in a colour representation, this means that the blue
0.88
areas are among the colder measured values in the current
0.89
measurement range. However, these areas may be in a tem-
perature range that could cause injuries in certain circum-
stances. You should therefore always note the temperatures
displayed on the scale or at the crosshairs themselves.
32,5 °C
21,8 °C
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