Campbell Scientific HMP155A Temperature and Relative Humidity Probe - Manual (Page 19)

HMP155A Temperature and Relative Humidity Probe
6.2 Relative Humidity Sensor
Measurement range: 0 to 100% RH
Accuracy (including non-linearity,
hysteresis and repeatability)
at +15° to 25°C (59 to 77°F): ±1% RH (0 to 90% RH)
±1.7% RH (90 to 100% RH)
at –20° to +40°C –4° to 104°F): ± (1.0 + 0.008 × reading) % RH
at –40° to –20°C –40° to –4°F): ± (1.2 + 0.012 × reading) % RH
at +40° to +60°C (104° to 140°F): ± (1.2 + 0.012 × reading) % RH
at –60° to –40°C –76° to –40°F): ± (1.4 + 0.032 × reading) % RH
Factory calibration uncertainty (+20°C): ±0.6% RH (0 to 40% RH)
±1.0% RH (40 to 97% RH)
(Defined as ±2 standard deviation
limits. Small variations possible,
see also calibration certificate.)
Humidity sensor: HUMICAP®180R
Response time for HUMICAP®180R(C)
at 20°C in still air with sintered PTFE filter: 63% 20 s
90% 60 s
7. Installation
If you are programming your datalogger with Short Cut, skip Section 7.2,
Wiring, and Section 7.3, Datalogger Programming. Short Cut does this work
for you. See Section 4, Quickstart, for a Short Cut tutorial.
7.1 Siting
Sensors should be located over an open level area at least 9 m (EPA) in
diameter. The surface should be covered by short grass, or where grass does
not grow, the natural earth surface. Sensors should be located at a distance of
at least four times the height of any nearby obstruction, and at least 30 m
(EPA) from large paved areas. Sensors should be protected from thermal
radiation, and adequately ventilated.
Standard measurement heights:
1.5 m (AASC)
1.25 – 2.0 m (WMO)
2.0 m (EPA)
See Section 10 for a list of references that discuss temperature and relative
humidity sensors.
7.2 Wiring
Connections to Campbell Scientific dataloggers are given in TABLE 7-1
through TABLE 7-3. The probe can be measured by two single-ended or
differential analog input channels (recommended for lead lengths > 6.1 m (20
ft.), see Section 7.4). The CR200(X)-series dataloggers only have single-ended
channels.
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