PAR

PAR

The PAR based on Apogee SQ-521 provides high-precision PAR and PPFD measurements, optimized for scientific and environmental monitoring. Its robust, waterproof design ensures reliable long-term operation in field stations, greenhouses, and aquatic research.

Contact for more information

WhatsAPP | +358 40 5022740 | sense@datasense.fi

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Description

The PAR measurement station is based on Apogee SQ-521 is a digital quantum sensor for precise measurement of photosynthetically active radiation (PAR, 400–700 nm).
It measures photosynthetic photon flux density (PPFD) in µmol m⁻² s⁻¹ and is ideal for agricultural, ecological, and environmental research both indoors and outdoors.
Using the SDI-12 digital interface, the SQ-521 integrates seamlessly into FluxScout systems, weather stations, and greenhouse monitoring networks.

Key Benefits and Applications

  • Research-grade accuracy for PAR and PPFD measurements in field or controlled environments

  • Full-spectrum response (389–692 nm) for sunlight and artificial lighting (LED, HPS, MH, fluorescent)

  • SDI-12 output – direct integration with FluxScout and other SDI-12 loggers

  • Rugged IP68 design, submersible up to 30 m for long-term field deployment

  • Excellent cosine response (± 2 % at 45°, ± 5 % at 75°) and low temperature dependence

  • Suitable for crop canopies, greenhouse lighting, flux chamber experiments, and aquatic PAR measurements

  • Factory calibration traceable to NIST standards for consistent, repeatable data

Technical Specifications

Feature Values
Model SQ-521 (SDI-12 digital output)
Measurement range 0 – 4000 µmol m⁻² s⁻¹
Spectral range 389 – 692 nm ± 5 nm
Spectral selectivity < 10 % (412–682 nm)
Calibration uncertainty ± 5 %
Measurement repeatability < 1 % (up to 4000 µmol m⁻² s⁻¹)
Non-linearity < 1 %
Response time 0.6 s (95 % signal response)
Temperature response –0.11 ± 0.04 % per °C
Long-term drift < 2 % per year
Field of view 180°
Operating environment –40 … +70 °C; 0–100 % RH; submersible to 30 m
Power supply 5.5 – 24 V DC
Current draw 1.4 mA (quiescent), 1.8 mA (active)
Housing Anodized aluminum with acrylic diffuser
Connector M8 stainless-steel, IP68-rated
Cable 5 m shielded, twisted-pair TPR jacket
Dimensions Ø 30.5 mm × 37 mm
Weight 140 g (with 5 m cable)
Protection rating IP68 (waterproof)
Calibration traceability NIST-traceable lamp reference
Origin Apogee Instruments Inc., USA
Warranty 4 years

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