LumaSense Technologies IN 5/5 - Handbuch (Seite 23)

INFRATHERM pyrometers IN 5 · IN 5/5
23
Measuring object EMI (at 8 ... 14 µm) Measuring object EMI (at 8 ... 14 µm)
"Black body furnace" 100% Brickwork
Human skin 98% Fire clay
Black dull varnish 95% Rubber
Carbon soot 95% Porcelain
Wood 80 ... 92% Ceramics
Paper 92 ... 95% Varnish
Asphalt 85% Plaster
Glass / quartz glass 72 ... 87% Oil paint
85... 95%
Textile 75 ... 95% Steel (oxidized) 60 ... 80%
Graphite 75 ... 92% Steel (smooth) 10 ... 30%
Cement 90% Aluminium (smooth) 2 ... 15%
Water 95% Aluminium (anodized) 90%
Measuring object EMI (at 5.14 µm)
Glass / quartz glass 97%
One way to determine an accurate emissivity value for a material is to make a comparison measurement as
follows: If possible, coat a portion of the object with dull black paint or carbon soot. Paint and carbon soot
have high emissivities (95%) and take on the same temperature as the object. Measure the temperature of
the painted area with the emissivity control set to 95%. Then measure the temperature of an adjacent un-
painted area of the object and adjust the emissivity until the pyrometer displays the same temperature.
9.1.2
Exposure time t
90
The exposure time t
90
is the time interval from the start of measurement up to the respective change in the
output signal (4 ... 20 mA) which is the time taken to reach 90% of the recorded temperature difference.
The exposure time is changed by adjusting the jumper position. In the open position shown in the diagram
on the left, the response time is 0.08 s.
For alternative settings (t
90
= 0.5 s, 1 s, 2 s or 5 s) select the respective jumper position (see diagram on the
right).
Longer exposure times are useful when measuring objects with fluctuating temperatures.
9.2
Factory settings
Emissivity (Emi) = 100%
Exposure time (t
90
) = 0.08 s
Example: t
90
= 0.08 s Example: t
90
= 0.5 s
Jumper to set the
exposure time t
90