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Summary of Contents for Hukseflux IR20
- Page 1 USER MANUAL IR20 Research grade pyrgeometer Copyright by Hukseflux | manual v1604 | www.huksefluxusa.com | info@huksefluxusa.com...
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Page 2: Warning Statements
Warning statements Putting more than 12 Volt across the sensor wiring can lead to permanent damage to the sensor. Do not use “open circuit detection” when measuring the sensor output. IR20 manual v1604 2/39... -
Page 3: Table Of Contents
Data quality assurance Appendices Appendix on cable extension / replacement Appendix on tools for IR20 Appendix on spare parts for IR20 Appendix on standards for classification and calibration Appendix on calibration hierarchy Appendix on meteorological radiation quantities Appendix on terminology / glossary... -
Page 4: List Of Symbols
(see also appendix 7.6 on meteorological quantities) Subscripts relating to the atmosphere surface relating to the ground surface ambient relating to ambient air body relating to the instrument body sensor relating to the sensor IR20 manual v1604 4/39... -
Page 5: Introduction
The spectral range of longwave radiation is not standardised. A practical cut-on is in the range of 4 to 5 x 10 IR20 has a dome with a solar blind filter with a cut-on at 4.5 x 10 m, making it suitable for day- and night observations. - Page 6 (5 %) and the two 50 % transmission points are displayed on the product certificate for individual sensors. Figure 0.1 IR20 research grade pyrgeometer with its sun screen removed More about the instrument principle, theory and specifications can be found in the following chapters.
- Page 7 See the specific paragraph in this manual about calibration and uncertainty assessment for more information. This manual is intended for users of both IR20 and IR20WS. The specifications of IR20WS are identical to IR20’s except for its spectral range. Figure 0.1 IR20WS research grade pyrgeometer...
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Page 8: Ordering And Checking At Delivery
The standard configuration of IR20 is with 5 metres cable and a connector. Common options are: Longer cable (in multiples of 5 m). Specify total cable length. Five silica gel bags in an air-thight bag for IR20 desiccant holder. Specify order number DC01. Optional calibration to blackbody (ITS-90). ... -
Page 9: Quick Instrument Check
6. Inspect the instrument for any damage. 7. Inspect if the humidity indicator is blue. Blue indicates dryness. The colour pink indicates it is humid: in the latter case replace the desiccant (see chapter on maintenance). IR20 manual v1604 9/39... -
Page 10: Instrument Principle And Theory
Instrument principle and theory 2.1 Pyrgeometer functionality IR20’s scientific name is pyrgeometer. IR20 measures the longwave or far-infra-red (FIR) radiation received by a plane surface, in W/m , from a 180 ° field of view angle. In meteorological terms pyrgeometers are used to measure “downward and upward longwave irradiance”... - Page 11 These effects are still under investigation by the international scientific community. Comparison between IR20 and IR20WS may serve to investigate this effect. Upwelling longwave irradiance is measured with downfacing instruments. These are presumably looking directly at the surface (absorption and emission of the atmosphere is low over a short distance of around 2 m), which behaves like a normal blackbody.
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Page 12: Ir20 Pyrgeometer Design
2.3 IR20 pyrgeometer design Figure 2.3.1 Overview of IR20 pyrgeometer: cable (standard length 5 metres, optional longer cable) fixation of sun screen dome with solar blind filter sun screen humidity indicator desiccant holder levelling feet bubble level connector By definition a pyrgeometer should not measure solar radiation, and in the longwave have a spectral selectivity that is as “flat”... - Page 13 Hukseflux also manufactures lower accuracy pyrgeometers; see our pyrgeometer model IR02. Model IR20 has a dome with a solar blind filter with a cut-on at 4.5 x 10 m, making it suitable for day- and night observations.
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Page 14: Typical Measurement Results
In case the two instruments are thermally coupled, the body temperatures of the instruments are identical. In that case the body temperature cancels from the equation for the net radiation. However for calculation of sky temperature and surface temperature the instrument temperature still needs to be measured. IR20 manual v1604 14/39... -
Page 15: Specifications Of Ir20 And Ir20Ws
It should be used in accordance with the recommended practices of WMO. IR20 measures during both day and night. In the absence of solar radiation IR20WS offers a higher accuracy because of its wider spectral range. For ultra-high accuracy measurements the user should consider to use the incorporated heater and should consider “shading”... - Page 16 Table 3.1.1 Specifications of IR20 and IR20WS (continued) ADDITIONAL SPECIFICATIONS Zero offset b (response to 5 K/h change < ± 2 W/m in ambient temperature) Non-stability < ± 1 % change per year Non-linearity < ± 0.5 % (100 to 300 W/m...
- Page 17 Table 3.1.1 Specifications of IR20 and IR20WS (started on previous pages) HEATING Heater operation the heater is not necessarily switched on; recommended operation is to activate the heater when there is a risk of dew deposition Required heater power 1.5 W at 12 VDC Heater resistance 95 Ω...
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Page 18: Dimensions Of Ir20
3.2 Dimensions of IR20 M5 (2x) Figure 3.2.1 Dimensions of IR20 and IR20WS in 10 IR20 manual v1604 18/39... -
Page 19: Standards And Recommended Practices For Use
For ultra high accuracy measurements, the following manual may serve as a reference: Baseline Surface Radiation Network (BSRN) Operations Manual, Version 2.1, L. J. B. McArthur, April 2005, WCRP-121, WMO/TD-No. 1274. This manual also includes chapters on installation and calibration. IR20 manual v1604 19/39... -
Page 20: Site Selection And Installation
60 % by “shading”, which means preventing the direct radiation to reach the instrument. Shading is typically done by using a shading disk on a solar tracker. IR20 manual v1604 20/39... -
Page 21: Installation Of The Sun Screen
4.2 Installation of the sun screen IR20’s sun screen can be installed and removed by using the dedicated thumb screw. See item 2 of the drawing below. The thumb screw can be turned without tools for fixation or loosening of the sun screen, as visualised below. Once the thumb screw has turned the sun screen loose, the screen can be lifted off manually. -
Page 22: Electrical Connection
In order to operate, a pyrgeometer should be connected to a measurement system, typically a so-called datalogger. IR20 is a passive sensor that does not need any power. Cables generally act as a source of distortion, by picking up capacitive noise. We recommend keeping the distance between a datalogger or amplifier and the sensor as short as possible. -
Page 23: Requirements For Data Acquisition / Amplification
IR20 are available. In case programming for similar instruments is available, this can typically also be used. IR20 can usually be treated in the same way as other thermopile pyrgeometers. Table 4.4.1 Requirements for data acquisition and amplification equipment for IR20 in... -
Page 24: Making A Dependable Measurement
* defined at Hukseflux as all factors outside the instrument that are relevant to the measurement such as the cloud cover (presence or absence of direct radiation), sun position, the local horizon (which may be obstructed) or condition of the ground (when inverted). -
Page 25: Reliability Of The Measurement
(within specifications). This is solved by regular replacement of desiccant or by maintenance (drying the entire sensor) in case the sensor allows this. For non- serviceable sensors like Hukseflux flat window pyrgeometers (for example model IR20 manual v1604 25/39... -
Page 26: Speed Of Repair And Maintenance
IR02), this may slowly develop into a defect. For model IR20 extra desiccant (in a set of 5 bags in an air tight bag) is available. One of the larger errors in the daytime measurement of downwelling longwave irradiance is the offset caused by solar radiation; the “solar offset”. Errors due to... - Page 27 This causes an uncertainty of the sensitivity S With IR20, this uncertainty is already taken into account in the WISG calibration of the reference instrument. With IR20WS this uncertainty does not play a significant role.
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Page 28: Maintenance And Trouble Shooting
Maintenance and trouble shooting 6.1 Recommended maintenance and quality assurance IR20 can measure reliably at a low level of maintenance in most locations. Usually unreliable measurements will be detected as unreasonably large or small measured values. As a general rule this means that regular visual inspection combined with a critical review of the measured data, preferably checking against other measurements, is the preferred way to obtain a reliable measurement. -
Page 29: Trouble Shooting
Replace the desiccant and wait a few days to see if the situation improves. In shows internal case of condensation of droplets: disassemble the instrument and dry out the condensation. parts. The instrument Arrange to send the sensor back to Hukseflux for diagnosis. shows persistent internal condensation IR20 manual v1604 29/39... -
Page 30: Calibration And Checks In The Field
Recalibration of field pyrgeometers is typically done by comparison in the field to a reference pyrgeometer. There is no standard for this procedure. Hukseflux recommendation for re-calibration: if possible, perform calibration outdoor by comparison to an identical or a higher class reference instrument, under nighttime as well as daytime conditions. -
Page 31: Appendices
Appendices 7.1 Appendix on cable extension / replacement The sensor cable of IR20 is equipped with a M16 straight connector. In case of cable replacement, it is recommended to purchase a new cable with connector at Hukseflux. An alternative is to choose for a Do-it-yourself (DIY) approach; please ask for the DIY connector assembly guide. -
Page 32: Appendix On Tools For Ir20
IR20 cable with connector (specify length in multiples of 5 m) O-ring IR20 NOTE: The dome of IR20 and IR20WS cannot be supplied as spare part. 7.4 Appendix on standards for classification and calibration Unlike pyranometers, pyrgeometers are not subject to a system of classification. -
Page 33: Appendix On Calibration Hierarchy
7.5 Appendix on calibration hierarchy Hukseflux pyrgeometers are traceable to the World Infrared Standard Group (WISG). WISG is composed of a group of pyrgeometers. The calibration hierarchy of Hukseflux IR20 is from WISG through Hukseflux internal calibration procedure involving outdoor comparison to a reference pyrgeometer. - Page 34 (transfer error). The coverage factor must be determined; at Hukseflux we work with a coverage factor k = 2. Hukseflux specifies a calibration uncertainty of < 6% (k = 2).
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Page 35: Appendix On Meteorological Radiation Quantities
A pyrgeometer measures longwave irradiance. The time integrated total is called radiant exposure. Table 7.6.1 Meteorological radiation quantities as recommended by WMO (additional symbols by Hukseflux Thermal Sensor). POA stands for Plane of Array irradiance. The term originates from ASTM and IEC standards. SYMBOL... -
Page 36: Appendix On Terminology / Glossary
The former is the direct component, the latter is the diffuse component of the solar radiation. (ref: WMO, Hukseflux) Hemispherical solar radiation received by a plane surface from a 180 ° field of view angle (solid solar radiation angle of 2 π... - Page 37 1. Surface equivalent blackbody radiative temperature of the surface; i.e. the temperature temperature calculated from pyrgeometer data measuring upwelling longwave radiation, assuming the ground behaves as a blackbody with an emission coefficient of 1. IR20 manual v1604 37/39...
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Page 38: Eu Declaration Of Conformity
7.8 EU declaration of conformity Hukseflux Thermal Sensors B.V. Elektronicaweg 25 2628 XG Delft The Netherlands in accordance with the requirements of the following directive: 2014/30/EU The Electromagnetic Compatibility Directive hereby declare under our sole responsibility that: Product model: IR20 and IR20WS... - Page 39 © 2016, Hukseflux Thermal Sensors B.V. www.hukseflux.com Hukseflux Thermal Sensors B.V. reserves the right to change specifications without notice.
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