The Apogee Guardian is a sleek device that provides accurate measurements of important indoor environmental parameters. The SM-500 is an easy-to-use data logger with multiple built-in sensors to measure PAR, air temperature, humidity, vapor pressure deficit and dew point, CO2 concentration, barometric pressure, and photoperiod* and daily light integral (*accessible via Bluetooth only). Graphical summaries of these measurements can be downloaded to the data loggers via Modbus or smartphones via Bluetooth with the Apogee Connect app (iOS/Android). While the SM-500 can take measurements as a stand-alone device mounted on a mast (AM-270, coming soon) or suspended from thin cables, it can also be integrated into systems for greenhouses, grow rooms, and vertical farms via Modbus or Bluetooth.
The SM-500 is constructed of high-grade ASA plastic with low thermal conductivity and a gloss white finish in selective areas to reduce emissivity. The Guardian is foam-filled to provide additional thermal insulation. The internal air duct uses a small Venturi constriction to maximize airflow efficiency over the thermistor, minimizing the influence of the thermal boundary layer on temperature measurements. At the same time, a separate module used to measure CO2, humidity, and pressure is drawn in by a passive low-velocity air stream using a “fluid drag” principle. Additionally, a quantum sensor is mounted on top of the shield to measure PAR.
The Guardian comes in two model versions: SM-500 and SM-600. The SM-500 and SM-600 models are identical in all aspects (size, function, and appearance) except for the built-in light sensor. The SM-600 sensor measures extended photosynthetically active radiation (ePAR), while the SM-500 measures PAR (400-700 nm). For the ePAR option, see our SM-600 model.
Depending on the package selected, there are different cable types and lengths available:
L-5: includes a 5-meter flexible cable
L-10: includes a 10-meter flexible cable (+$25)
L-20: includes a 20-meter flexible cable (+$50)
AC: includes a 5-meter power-only USB cable and an AC adapter
SPECIFICATION
- Calibration Uncertainty: ± 5 %
- Long-term drift (non-stability): Less than 2 % per year
- Measurement Repeatability: Less than 0.5 %
- Measurement Range: 0 to 4000 µmol m-2 s-1
- Spectral Range: 389 to 692 nm
- Field of View: 180°
- Directional Response: ± 5 % at 75° zenith angles
- Azimuth Angle: Less than 0.5 %
- Tilt Error: Less than 0.5 %
- Non-linearity: Less than 1 % (up to 4000 µmol m-2 s-1)
- Response Time: Less than 1 ms
- Temperature Response: -0.11 % ± 0.04 % per C
- Uncertainty in Daily Total: Less than 5 %
- Operating Environment: -40 to 60 C with 0 to 95 % relative humidity Housing: White ASA housing CO2
- Range: 0-2000; ± 50 ppm + 2 %
- Temperature: ± 0.2 C
- Humidity Range: 0-95 %; ± 3 % 20-80 % Vapor
- Pressure Deficit (25 C): ± 0.08 kPa
- Barometric Pressure: 70 to 110 kPa
- Connectivity: Modbus (RS232 and RS485) and Bluetooth Power Requirements: 5-32 V DC; Typical: 100 mA; Peak: 500 mA
- Data Storage Capacity: 9 months of 1 min data
- IP Rating: IP53 rating for harsh environments
- Dimensions: 105 mm diameter, 157 mm height
- Mass: 392 g
- Cable: 6 conductor, shielded wire with TPR jacket and M8 connector (available in 5, 10, and 20 m lengths; 5 V 1A USB power adapter and 5 m USB to M8 connector cable)
- Warranty: 4 years against defects in materials and workmanship
- Manufactured: Assembled in the USA
