RS 611-391 Hoja De Instrucciones

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Instruction Leaflet
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A non-saturated lithium chloride solution is used to generate a humidity
of approximately 50%rh in the calibration chamber supplied with the
thermo-hygrometer. A set of 5 sealed glass ampoules containing this
solution are provided in a polystyrene box. These may be stored
indefinitely out of direct sunlight and avoiding temperature extremes.
The lithium chloride solution in the quantities contained within the
ampoules is considered to be of low risk. It does not produce harmful
fumes, nor is skin contact dangerous; a toxicity risk exists only if the
solution is swallowed in large quantities.
Calibration Procedure
The following procedure should only be considered a 'spot-check' of
the performance accuracy of the instrument. It is recommended that at
least annually a 2-point check should be carried out to assess response
linearity and any offset that may have arisen resulting from exposure to
airborne pollutants.
The calibration should take place in a room at constant temperature
with the instrument shielded from thermal effects such as draughts,
direct sunlight and sources of heat. The instrument should also be in
thermal equilibrium with the test room – for an instrument brought in
from another area allow at least 1 hr for equilibrium to occur.
During calibration the probe of the instrument should be placed on an
insulated block e.g. the lid of the ampoule box, to eliminate any surface
temperature effects.
1. Unscrew the knurled cover of the calibration chamber, ensure that
it and the chamber are free from contamination from previous tests.
2. Insert the probe through the clamping ring of the chamber. Ensure
that the sensor filter is completely inside the chamber and tighten
the clamping ring to provide an airtight seal.
3. Using a pair of tweezers place a multi-layer cotton disc from the
calibration pack into the knurled cover. n.b. physical contact with the
disc should be avoided as this can contaminate the disc and affect
the resultant value.
4. Shake the calibration solution into the larger part of the ampoule.
Exerting equal pressure from thumb and forefinger of each hand
break the ampoule at the point marked by the white circle.
Solutions standard pur étalonnage
5. Immediately pour the liquid onto the centre of the cotton disc
RS Stock No.
6. Screw the cover back onto the calibration device ensuring that the
611-391
7. With the calibration device resting on the polystyrene lid leave the
8. Note this value and compare it with the value indicated on the
Adjustment:
Should the value obtained lie outside this tolerance band with some
instruments – A1, M1, and S1 models, a trimming potentiometer is
accessible on the side of the housing. Using a small screwdriver the
readout can be adjusted to compensate the offset. However should the
offset be significant (>±4%rh) then it is recommended that the
instrument be returned for investigation and correction.
Other instruments e.g. A1H, Hygrolog, Hygrowin do not have trimming
potentiometers as adjustment is carried out using software. In these
cases should an offset be noted a correction factor can be applied to
the measured values. As above should the offset be significant
(>±4%rh) then it is recommended that the instrument be returned for
investigation and correction.
9. On completion of calibration the calibration device should be
RS Components shall not be liable for any liability or loss of any nature (howsoever
caused and whether or not due to RS Components' negligence) which may result
from the use of any information provided in RS technical literature.
01/2001
Humidity standards
Luftfeuchtigkeitsstandards
Estandares de humedad
Standarder for lugtfugtighed
Vochtigheidsstandaards
Standarder för luftfuktighet
ensuring that all the solution is used.
chamber is positioned so that the cover is underneath the probe.
This ensures that the disc and solution cannot drop onto the probe
and therefore contaminate it.
assembly to equilibrate for 45 minutes. Switch the instrument on
and note the reading. To ensure that equilibrium has been achieved
leave the assembly for a further minute and repeat the reading.
Continue this procedure until there is no significant difference
between the readings.
calibration certificate supplied with the ampoules. This also
indicates the accuracy that can be expected using the ampoules in
the manner indicated. An instrument can be considered as being 'in
calibration' provided the value obtained lies within ±2%rh of the
calibration value.
removed, he knurled cover unscrewed and the cotton disc disposed
of in a safe manner. The complete assembly should then be washed
out and dried. Should further calibrations be required spare knurled
covers can be supplied.
V6760
d'hygromêtre
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