OWNER’S MANUAL QUANTUM SENSOR Models SQ-512 and SQ-515 (including SS models) APOGEE INSTRUMENTS, INC. | 721 WEST 1800 NORTH, LOGAN, UTAH 84321, USA TEL: (435) 792-4700 | FAX: (435) 787-8268 | WEB: APOGEEINSTRUMENTS.COM Copyright © 2018 Apogee Instruments, Inc.
TABLE OF CONTENTS Owner’s Manual ............................................................................................................................................................................... 1 Certificate of Compliance ......................................................................................................................................................... 3 Introduction ..........................................................................................................
CERTIFICATE OF COMPLIANCE EU Declaration of Conformity This declaration of conformity is issued under the sole responsibility of the manufacturer: Apogee Instruments, Inc.
INTRODUCTION Radiation that drives photosynthesis is called photosynthetically active radiation (PAR) and is typically defined as total radiation across a range of 400 to 700 nm. PAR is often expressed as photosynthetic photon flux density (PPFD): photon flux in units of micromoles per square meter per second (µmol m-2 s-1, equal to microEinsteins per square meter per second) summed from 400 to 700 nm (total number of photons from 400 to 700 nm).
SENSOR MODELS This manual covers quantum sensor models SQ-512 and SQ-515, which provide a voltage signal. Additional models are covered in their respective manuals. Model Signal SQ-512 0-2.5 V SQ-515 0-5 V SQ-500 Self-powered SQ-520 USB SQ-521 SDI-12 SQ-522 Modbus Sensor model number and serial number are located near the pigtail leads on the sensor cable. If you need the manufacturing date of your sensor, please contact Apogee Instruments with the serial number of your sensor.
SPECIFICATIONS SQ-512 Power Supply SQ-515 3.3 to 24 V DC, current draw at 12 V is 57 µA Sensitivity Calibration Factor (Reciprocal of Sensitivity) Calibration Uncertainty Measurement Range 5.5 to 24 V DC, current draw at 12 V is 57 µA 0.625 mV per µmol m-2 s-1 1.25 mV per µmol m-2 s-1 1.6 µmol m-2 s-1 per mV 0.
Spectral Response Mean spectral response measurements of six replicate Apogee SQ-100 (original) and SQ-500 (full-spectrum) series quantum sensors. Spectral response measurements were made at 10 nm increments across a wavelength range of 300 to 800 nm in a monochromator with an attached electric light source. Measured spectral data from each quantum sensor were normalized by the measured spectral response of the monochromator/electric light combination, which was measured with a spectroradiometer.
Cosine Response Directional, or cosine, response is defined as the measurement error at a specific angle of radiation incidence. Error for Apogee SQ-500 series quantum sensors is approximately ± 2 % and ± 5 % at solar zenith angles of 45° and 75°, respectively. Mean cosine response of seven apogee SQ-500 quantum sensors. Cosine response measurements were made on the rooftop of the Apogee building in Logan, UT.
DEPLOYMENT AND INSTALLATION Mount the sensor to a solid surface with the nylon mounting screw provided. To accurately measure PPFD incident on a horizontal surface, the sensor must be level. An Apogee Instruments model AL-100 Leveling Plate is recommended to level the sensor when used on a flat surface or being mounted to surfaces such as wood. To facilitate mounting on a mast or pipe, the Apogee Instruments model AL-120 Solar Mounting Bracket with Leveling Plate is recommended.
CABLE CONNECTORS Apogee started offering in-line cable connectors on some bare-lead sensors in March 2018 to simplify the process of removing sensors from weather stations for calibration (the entire cable does not have to be removed from the station and shipped with the sensor). The ruggedized M8 connectors are rated IP68, made of corrosion-resistant marine-grade stainless-steel, and designed for extended use in harsh environmental conditions.
OPERATION AND MEASUREMENT Connect the sensor to a measurement device (meter, datalogger, controller) capable of measuring and displaying or recording a millivolt signal (an input measurement range of approximately 0-2.5 V (SQ-512) or 0-5 V (SQ-515) is required to cover the entire range of PPFD from the sun). In order to maximize the measurement resolution and signal-to-noise ratio, the signal input range of the measurement device should closely match the output range of the quantum sensors.
Sensor Calibration Apogee amplified quantum sensor models have a standard PPFD calibration factor of exactly: SQ-512: 1.6 µmol m-2 s-1 per mV SQ-515: 0.8 µmol m-2 s-1 per mV Multiply this calibration factor by the measured mV signal to convert sensor output to PPFD in units of µmol m-2 s-1: Calibration Factor (0.8 µmol m-2 s-1 per mV) * Sensor Output Signal (mV) = PPFD (µmol m-2 s-1) 0.8 Full Sunlight (2000 µmol m-2s-1) * 2500 = 2000 Example of PPFD measurement with an Apogee quantum sensor.
Spectral Errors for PPFD and YPFD Measurements with Apogee SQ Series Quantum Sensors Radiation Source (Error Calculated Relative to Sun, Clear Sky) Sun (Clear Sky) Sun (Cloudy Sky) Reflected from Grass Canopy Transmitted below Wheat Canopy Cool White Fluorescent (T5) Metal Halide Ceramic Metal Halide High Pressure Sodium Blue LED (448 nm peak, 20 nm full-width half-maximum) Green LED (524 nm peak, 30 nm full-width half-maximum) Red LED (635 nm peak, 20 nm full-width half-maximum) Red LED (668 nm peak, 20 nm
One potential definition of PAR is weighting photon flux density [µmol m-2 s-1] at each wavelength between 300 and 800 nm by relative quantum yield and summing the result. This is defined as yield photon flux density (YPFD) [µmol m-2 s-1] (Sager et al., 1988). There are uncertainties and challenges associated with this definition of PAR. Measurements used to generate the relative quantum yield data were made on single leaves under low radiation levels and at short time scales (McCree, 1972a; Inada, 1976).
MAINTENANCE AND RECALIBRATION Moisture or debris on the diffuser is a common cause of low readings. The sensor has a domed diffuser and housing for improved self-cleaning from rainfall, but materials can accumulate on the diffuser (e.g., dust during periods of low rainfall, salt deposits from evaporation of sea spray or sprinkler irrigation water) and partially block the optical path. Dust or organic deposits are best removed using water, or window cleaner and a soft cloth or cotton swab.
Homepage of the Clear Sky Calculator. Two calculators are available: one for quantum sensors (PPFD) and one for pyranometers (total shortwave radiation). Clear Sky Calculator for quantum sensors. Site data are input in blue cells in middle of page and an estimate of PPFD is returned on right-hand side of page.
TROUBLESHOOTING AND CUSTOMER SUPPORT Independent Verification of Functionality Apogee SQ-512 and SQ-515 quantum sensors provide an amplified voltage output that is proportional to incident PPFD. A quick and easy check of sensor functionality can be determined using a DC power supply and a voltmeter. Power the sensor with a DC voltage by connecting the positive voltage signal to the red wire from the sensor and the negative (or common) to the black wire from the sensor.
Unit Conversion Charts Apogee SQ series quantum sensors are calibrated to measure PPFD in units of µmol m -2 s-1. Units other than photon flux density (e.g., energy flux density, illuminance) may be required for certain applications. It is possible to convert the PPFD value from a quantum sensor to other units, but it requires spectral output of the radiation source of interest. Conversion factors for common radiation sources can be found in the Knowledge Base on the Apogee website (http://www.
RETURN AND WARRANTY POLICY RETURN POLICY Apogee Instruments will accept returns within 30 days of purchase as long as the product is in new condition (to be determined by Apogee). Returns are subject to a 10 % restocking fee. WARRANTY POLICY What is Covered All products manufactured by Apogee Instruments are warranted to be free from defects in materials and craftsmanship for a period of four (4) years from the date of shipment from our factory.
How To Return An Item 1. Please do not send any products back to Apogee Instruments until you have received a Return Merchandise Authorization (RMA) number from our technical support department by calling (435) 792-4700 or by submitting an online RMA form at www.apogeeinstruments.com/tech-support-recalibration-repairs/. We will use your RMA number for tracking of the service item. 2. Send all RMA sensors and meters back in the following condition: Clean the sensor’s exterior and cord.
