VU01

Ventilation unit for SR20, SR20-D2, SR22, IR20 & IR20WS

VU01 is a high-quality ventilation unit for use with pyranometers and pyrgeometers. Its purpose is to improve the dependability of the measurement. Measurement accuracy improves because offsets are reduced. Reliability benefits from prevention of dew and frost formation and quick evaporation and sublimation of water and snow. ISO/TR 9901 “Solar Energy – Field Pyranometers – Recommended practice for use” recommends use of ventilators where high accuracy and reliability are required. VU01 is designed in agreement with the recommendations of ISO/TR 9901 and BSRN.

  • VU01 provides an airflow over the instrument body and dome and has two heaters on board to heat the air.
  • VU01 is designed, using high-quality materials, in agreement with the recommendations of ISO/TR 9901 and BSRN.
  • The footprint of VU01 is small, which prevents accumulation of snow
  • Dew and frost formation is prevented.
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Description

Compatibility
VU01 may be used in combination with Hukseflux’ SR20, SR20-D1, SR20-D2, SR22, SR25 and SR25-D2 secondary standard pyranometers and IR20 and IR20WS research grade pyrgeometers. VU01 provides an airflow over the instrument body and dome and has two heaters on board to heat the air. The use of heating (5 W or 10 W) is optional. The VU01 ventilation unit runs on 12 VDC voltage.

Improved Measurement Dependability
Ventilation promotes thermal equilibrium between all components of radiometers, and thereby reduces zero offsets. Dew and frost formation is prevented. Additional heating will promote evaporation of water droplets and sublimation of snow. It should be noted that heating in combination with pyranometers will lead to increased thermal offsets, so heating is only recommended if necessary.

Operation
Using VU01 is easy. The footprint of VU01 is small, which prevents accumulation of snow. The ventilator power is relatively high in order to increase the airflow. The ventilator is generally used continuously; the heater is typically controlled by the datalogger. Ventilation is typically used with high accuracy measurement requirements. In such cases the need for a high level of instrument maintenance and dome cleaning still exists; evaporating droplets of water might leave stains on the instrument domes. The bottom of VU01 provides access to the removable dust filter. For more information on VU01 please download the product brochure or ask for the user manual.

Suggested Use

  • PV system performance monitoring
  • Scientific meteorological observations
  • Extreme climates (tropical / polar)

Areas of Application

  • Meteorology / surface energy flux measurement
  • Solar energy / PV system performance monitoring

Accessories

  • VMA01

Specifications

Compatible instruments

SR20, SR20-D1, SR20-D2, SR22, SR25, SR25-D2, IR20, IR20WS
Compliance with standards

ISO/TR 9901, BSRN operations manual
Rated operating power

7.8 W at 12 VDC (unheated)
Rated operating voltage range

10.8 to 13.2 V
Rated operating temperature range

-40 to +70 °C
Fan status signal

high / low output (optional use)
Heater

5 and 10 W at 12 VDC (optional use)
Increase of air temperature

0.5 °C at 0 W heating, 1.0 °C at 5 W heating, 1.5 °C at 10 W heating
Zero offset a reduction SR20

50 % at 0 W heating
Offset SR20 by heating

-2 W/m² at 5 W heating and -4 W/m² at 10 W heating
Offset IR20 by heating

0 W/m² at 5 W heating and 0 W/m² at 10 W heating
Cable resistance

0.3 Ω/m (2 x 0.15 Ω/m)
Voltage drop at 10 W heating power

0.12 V/m
Footprint diameter

0.17 m
Standard cable length

5m (see options)

Downloads

Download Product Brochure

Download Product Manual

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