PurpleAir Air Quality Sensor PA-II-SD

PurpleAir Air Quality Sensor PA-II-SD

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PA-II-SD: With microSD


1) PA-II Dual Laser Sensor.
2) Built in 16Gb microSD Card (Good to store two years of data).
3) Built in Real Time Clock with battery backup keeps accurate time.



PurpleAir sensors use a fan to draw air past a laser, causing reflections from any particles in the air. These reflections are used to count particles in six sizes between 0.3μm and 10μm diameter.

Using one second particle counts, estimated total mass for PM1.0, PM2.5 and PM10 is averaged by the PurpleAir Internet of Things (IOT) control board.

Readings are then uploaded to the cloud every 80 seconds or so where they are stored for download and display on the PurpleAir map.

Technical Specifications

Power Supply

Outdoor power supply with 33 foot leads:
Output Voltage: 5 Volt (V)
Output Current: 2 Amps (A)

General Specifications

DC Power Supply Requirements: Typ:5.0 Min:4.5 Max: 5.5 Volt (V)
Active Current: ≤200 Milliampere (mA)
Peak Current: ≤600 Milliampere (mA)
Working Temperature Range: -20~+60 °C (-4~+140 °F)
Working Humidity Range: 0~99%
Physical Size 85 x 125 Millimeter (mm)(3.5 x 5 Inches)

BME280: Pressure / Temperature / Humidity

Operation range (full accuracy)
Pressure: 300…1100 hPa
Temperature: -40…85 °C
Humidity sensor response time (τ63%): 1s
Accuracy tolerance: ± 3 % relative humidity
Hysteresis: ≤ 2 % relative humidity"

Dual laser particle counters for fault tolerance:

Range of measurement: 0.3~1.0; 1.0~2.5; 2.5~10 Micrometer (μm)
Counting Efficiency: 50%@0.3μm 98%@>=0.5μm
Effective Range: 0~500 μg/m³
Maximum Range: * ≥1000 μg/m³
Resolution: 1 μg/m³
Maximum Consistency Error: ±10%@100~500μg/m³ ±10μg/m³@0~100μg/m³
Standard Volume: 0.1 Litre (L)
Single Response Time: ≤1 Second
Total Response Time: ≤10 Seconds

Wireless Specifications

WiFi 2.4 GHz, supports WPA/WPA2
Wireless Standards: 802.11 b/g/n
Certificates: FCC/CE/TELEC/SRRC

Tx Power:

802.11 b: +20 dBm
802.11 g: +17 dBm
802.11 n: +14 dBm

Rx Sensitivity:

802.11 b: -91 dbm (11 Mbps)
802.11 g: -75 dbm (54 Mbps)
802.11 n: -72 dbm (MCS7)
Type of Antenna: External, IPEX Connector, Ceramic Chip

* Optional SD Card Slot and Real Time Clock:

Extremely accurate DS3231 real-time clock (RTC) incorporates a battery backup and maintains accurate time keeping when main power to the device is interrupted.

A built in microSD card slot takes microSD cards up to 64GB for storage that will never run out.

PurpleAir sensors receive firmware updates over the air when connected to the Internet.