The DMA570 sensor measures:

-air temperature[°C];

- relative humidity[%].

WMO (1992) defines air temperature as “the temperature indicated by a thermometer exposed to the air in a place sheltered from direct solar radiation”. Although this definition cannot be used as the definition of the thermodynamic quantity itself, it is suitable for most applications.

At the Forni AWS the DMA570 Lsi-Lastem Thermohygrometer is mounted on a 2 m pole.

It is a probe for measuring air temperature and air relative humidity with replaceable sensitive element for simplify calibration and maintenance. LSI-Lastem supplies a precise and reliable set of probes, suitable for a continuous measurement in severe environments, in presence of deep thermal and hygrometric ranges with high sun radiant heat. An important feature of this set of sensor is that the thermohygrometric sensitive element is easily replaceable, in order to have a simple and rapid ordinary maintenance and avoiding calibration. The Thermohygrometer has supported a considerable improvement, owing to a deep technical and styling development process: a fan ensures a continuos air change around the sensor in order to eliminate temperature fault caused by radiant heat.

For temperature:

Range -30.+70°C

Sensitive element Pt100 1/3 DIN-B

Accuracy ± 0,1°C (0°C)

Hysteresis&Repeatability na

Resolution 0,025°C

Long term stability -0.04% (after 5 years at 200°C)

Calibration uncertainty 0,1°C

Response time (T63) Wind speed 0,3-0,5 m/s: 80sec

Radiation shield efficiency with respect to forced ventilation sensor (wind 0,5m/s, rad.800 W/m2): +0,6°C

For relative humidity:

Range: Nom.0..100%, Eff.10..98%

Sensitive element Capacitive

Accuracy 2,5% (11-90%) 0,6°C (20°C, 50%RH)

Hysteresis&Repeatability 0,5%

Resolution 0,2%

Long term stability -2%/year (at 75%RH) n.a.

Calibration uncertainty 0,1°C 1,5% na

Response time (T63) Wind speed 0,3-0,5 m/s: 80sec

Radiation shield efficiency with respect to forced ventilation sensor (wind 0,5m/s, rad.800 W/m2): n.a.

General characteristic:

Ventilation: Natural

Electric output Jumper locally selectable 2 x 0-20 mA, 4-20 mA, 0-5 V, 1-5 V. 60-300 mV

Output signals Output n.1: temperature. Output n.2: RH% or dew point (default RH%)

Operating temperature -30°+70°C

Sampling rate 1 sec. (default) PC programmable 1..300 sec.

N°acquisitions for mobile average calculation: N°1 (default), PC programmable 1..20 acquisitions

Load resistance (mA output): DMA570 300 Ohm