Troubleshooting; Specifications - ACR Electronics SmartReader Plus Reference Manual

SmartReader Plus Data Loggers
69
Interchangeable replacement RH sensors for loggers are available through your dealer. For
best accuracy, it is recommended these be calibrated together with the logger - consult your
ACR representative for price and availability of this service.
1.14.5

Troubleshooting

If you are getting what appear to be wrong readings, consider the following before recalibrating
the sensors. Sensors sample the atmosphere (or medium) in the immediate vicinity of the
sensors themselves. The physical state of the atmosphere and its degree of uniformity and
turbulence will limit the validity of a measurement at some distance from the sensor. This
becomes especially apparent for the measurement of ambient temperature and relative
humidity.
In a room, temperature and RH levels may vary dramatically from location to location. Such
factors as air stratification, drafts and proximity to heat or humidity sources (people,
equipment, moisture, solar gain, etc.) can contribute to a wide variance in conditions even
within a small confined area. The individual sensors associated with your Conservation
Logger measure and record temperature and RH only in one location. They do not, in any
way, represent an overall reading.
If you decide to check the calibration of your Conservation Logger RH sensor using a Sling
Psychrometer, keep in mind the following:
· Any instrument that requires a person to be present at, or in very close proximity to the
RH sensor in order to get a reading, will have a measurement error introduced to it.
That is because the body readily gives off heat and moisture that is especially
noticeable at lower RH levels.
· The time taken between slinging the psychrometer and reading it can exhibit several
degrees of inaccuracy in the wet bulb reading. Air currents around the body, whether it
is slung in the shade of a building or in sunlight, not knowing how to tie the wet sock, its
condition, and the purity of water used, all contribute to error. In addition, interpolating
the data from a psychrometric chart can add another 2 to 4% to the accumulative error.
1.14.6

Specifications

Temperature Sensor
Type:
Range:
Accuracy:
Resolution:
RH Sensor
Type:
NTC Thermistor
(-40 to 158
-40 to 70°C
+/- 0.2°C over the range of 0 to 70°C
(+/- 0.3°F over the range of 32 to 158°F)
0.03°C at 25°C (0.05°F at 77°F);
better than 0.07°C (0.12°F) between -25 and 70°C (-13 and
better than 0.13°C (0.23°F) between -40 and -25°C (-40 and
Capacitive thin polymer film
Copyright © 2010 ACR Systems Inc. All Rights Reserved.
)
°F
158°F);
-13°F)