Hart Sceintific DewK 1620, Руководство пользователя

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The sensor contains a memory device that stores information about the sensor
and automatically transfers this data to the thermo-hygrometer when the sensor
is attached. This ensures that the settings used to measure and calculate temper-
ature and humidity always match the sensor being used.
Caution: Sensors are fragile devices that can be easily damaged by me-
chanical shock, overheating, and exposure to fluids or dust. Damage may
not be visibly apparent but nevertheless can cause drift, instability, and
loss of accuracy. Observe the following precautions:
•
DO NOT allow sensors to be dropped, struck, or stressed.
•
DO NOT overheat sensors beyond their recommended temperature range.
•
DO NOT expose sensors to harmful vapors, fumes, dust, or condensation.
•
DO NOT allow sensors to come into direct contact with any fluids.
6.12.1 Sensor Accuracy
To achieve full accuracy with the thermo-hygrometer sensors, a few precau-
tions should be noted.
First, consider that the sensor actually measures its own temperature, not neces-
sarily the temperature of the air around it. Ideally, the sensor's temperature will
be the same as the air, but they might be different under less than ideal
conditions.
One such condition is when there is a source of radiated heat that is "seen" by
the sensor. Radiated heat tends to heat up the sensor higher than the air around
it (try shining a flashlight on the sensor from some distance away). Some
sources of radiated heat to avoid are incandescent lamps, space heaters, and
other high-temperature devices. If such objects cannot be eliminated, consider
using a heat shield between the heat source and the thermo-hygrometer sensor.
The sensor can also be heated by warm objects close by, perhaps a wall that is
slightly warmer than the air in the room or even another sensor placed next to
it. For best results, allow adequate distance between the sensor and any objects
that might be at a different temperature than the air.
Other considerations relate to the self-heating of the sensor. Since the sensor
contains electronic circuits that release a small amount of heat, the sensor will
naturally be slightly warmer than the air around it. The calibration of the sensor
takes this self-heating into account and compensates for it. But, factors that al-
ter the natural self-heating can cause errors in the measurement.
Self-heating does depend somewhat on the velocity of the air around the sensor.
The sensor is calibrated in nearly still air. Different air velocities can cause dif-
ferences in the measured temperature of the sensor: as much as ±0.06°C for ve-
24 Hart Scientific
6 General Operation