DAVIS Vantage Pro2 with Fan/Shield - Manual (Page 7)

Fan-Aspirated Shield Specifications
7
3. Remove the fan batteries.
4. Install new batteries (NiCad C-cells). Be
sure to match the “+” sign on the battery
with the “+” sign in the battery compart-
ment.
Theory of Operation
The diagram below shows how the Fan-Aspirated Radiation Shield draws out-
side air up through the sensor chamber and between the three walls surround-
ing the sensor chamber, while the shield stack prevents radiation heating of the
outer wall.
Cross-section of Fan-Aspirated Radiation Shiel
d
Fan-Aspirated Shield Specifications
Aspiration Rate (at the sensor) . . . . . . . . . 190 ft./min. (.96 m/s) (solar-powered, full
sun), 80 feet/min. (0.4 m/s) (battery only)
Radiation-Induced Temperature Error . . . . 0.5°F (0.3°C)
[At solar noon, insolation = 1040 W/m2]
(Reference: RM Young model 43408)
Operating Temperature . . . . . . . . . . . . . . –40° to +140° F (–40° to +60° C)
Non-operating Temperature . . . . . . . . . . . –50° to +158° F (–45° to +70° C)
Fan Primary Power Input
ISS . . . . . . . . . . . . . . . . . . . . . . . . . . solar panel
Fan secondary power . . . . . . . . . . . . 1 or 2 - 1.2 Volt NiCad C-cells
#4 Screws
Battery Cover
1.2 Volt Nicad
Battery
O-Ring
Battery
Compartment
Air
Flow
MOTOR
FAN
SENSOR
CHAMBER