-
8
-
5 Maintenance:
It is important to keep the outer glass dome clean to grant measurement best accuracy.
Consequently, the more the dome will be kept clean, the more measurements will be
accurate. Washing can be made using water and standard papers for lens, or, in some
cases, using pure ethyl alcohol. After using alcohol, clean again the dome with water
only.
Because of the high rise/fall in temperature between day and night, some condensation
might appear on the radiometer dome. To minimize the condensation growth, the
radiometer is provided with a cartridge containing dessicant material: Silica gel. The
efficiency of the Silica gel crystals decreases in the course of time while absorbing
humidity. Silica gel crystals are active when their color is
yellow
, while they turn
blue
as soon as they loose their power. Read instructions at paragraph
“3”
about how to
replace them. Silica gel typical lifetime goes from 2 to 6 months depending on the
environment where the radiometer works.
6 Calibration and Measurements:
LP UVA 02
The radiometer
S
sensitivity (or calibration factor) allows to determine the irradiance
by measuring a signal in Volts at the ends of the resistance which short-circuits the
terminals of the photodiode ends. The
S
factor is measured in
μ
V/(Wm
-2
).
Once the difference of potential (DDP) has been measured at the ends of the sensor,
the E
e
irradiance is obtained applying the following formula:
E
e
= DDP/S
Where:
E
e
:
is the Irradiance expressed in W/m
2
,
DDP: is the difference of potential expressed in
μ
V and measured by the
multimeter,
S:
is the calibration factor in
μ
V/(W/m
2
) shown on the radiometer label
(and mentioned in the calibration report) .
LP UVA 02 AC
The radiometer sensitivity is set so that:
4..20 mA = 0..200 W/m
2
To obtain irradiance the following procedure is to be applied:
-once you know the current ( I
out
) absorbed by the instrument and measured with
the DMM, following formula must be applied:
(
)
mA
I
e
out
E
4
5
.
12
−
⋅
=
where;
E
e
:
Irradiance in W/m
2
,
I
out
:
current in mA absorbed by the radiometer
