VU01
Ventilation unit for SR20 and SR22 pyranometers and IR20 pyrgeometers
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- improves measurement accuracy
- reduces offsets
- with optional heating
Ventilation unit for SR20 and SR22 pyranometers and IR20 pyrgeometers
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 mitigation of dew and frost and quick evaporation and sublimation of water and snow. ISO/TR 9901 “Solar Energy—Field Pyranometers—Recommended practice for use” recommends the use of ventilators where high accuracy and reliability are required.
- improves measurement accuracy
- reduces offsets
- with optional heating
Specifications
| instrument compatibility | SR20, 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 temperature range | (-40 to +70) °C |
| fan status signal | available (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 SR20 ventilated | 2.5 W/m² at 0 W heating |
All specifications
| instrument compatibility | SR20, 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 temperature range | (-40 to +70) °C |
| fan status signal | available (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 SR20 ventilated | 2.5 W/m² at 0 W heating |
| offset SR20 by heating | - 2 W/m² at 5 W heating, - 4 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 | 5 m (see options) |
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Enhancing pyranometers and pyrgeometers
Ventilation unit VU01 may be used in combination with Hukx’s SR20, SR22 and SR25 Class A 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. Deposition of dew and frost are mitigated. 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.
Maintenance/cleaning
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.
Operation
Using VU01 is easy. The ventilator is generally used continuously; the heater is typically controlled by the data logger. ISO/TR 9901 “Solar Energy—Field Pyranometers—Recommended practice for use” recommends the use of ventilators where high accuracy and reliability are required.
More details can be found in Paragraph 4.5.2 and annex A. The Baseline Surface Radiation Network, BSRN, recommends ventilation for radiometers in its BSRN operations manual v2.1.
VU01 design
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 the accumulation of snow.
The ventilator power is relatively high in order to increase the airflow. The heaters should be activated using external relays. A fan status signal may be used by the user to monitor rotation of the fan.
Choosing the right instrument
Pyranometers are subject to classification in three classes according to ISO 9060.
Our pyranometer selection guide assists you in choosing the right instrument. Whatever your application is: Hukx offers the highest accuracy in every class at the most attractive price level.
Suggested use
- PV system performance monitoring
- scientific meteorological observations
- extreme climates (tropical/polar)
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