PAX
Photoacoustic Extinctiometer
The PAX is a sensitive, high-resolution, fast-response instrument for measuring aerosol optical properties relevant for climate change and carbon particle sensing.
TALK TO AN EXPERTGet accurate measurements for both light absorption and scattering in a single instrument. Then correlate the absorption measurement black carbon mass concentration.
Get continuous and autonomous operation, with no filter collection required and no filter data artifacts.
Count on fast response, one-second resolution, and real-time data display on a high-resolution touch screen.
Achieve excellent scattering coefficient sensitivity with reciprocal nephelometry.
Select from three wavelengths (870 nm [standard], optional 405 nm, or 532 nm), and get wide dynamic range suitable for pristine regions to source sampling.
PAX Software
The PAX is controlled by fully-integrated software that presents an intuitive user interface via either the front-panel touchscreen or a web browser on any networked computer. With this interface, you get:
- Real-time display of measured and calculated data and instrument status, plus configuration of the instrument’s operating parameters
- Password-protected access via web browser, with full instrument operation and configuration from remote locations
- Data written to an easy-to-read ASCII file – which can be downloaded, archived, and displayed via an external program on a network-connected computer
- The capability to upload calibration information to the PAX and perform other maintenance functions
Particle light-scattering and photoacoustic absorption
- Modulated diode laser simultaneously measures light scattering and absorption.
- Absorbing particles heat up and quickly transfer heat to the surrounding air. The periodic heating produces pressure waves that can be detected with a sensitive microphone and quantified to determine aerosol light absorption.
- Wide-angle integrating reciprocal nephelometer measures the light scattering coefficient of all particles.
- PAX laser wavelength options include:
- Red (870 nm) ¬– absorption is highly specific for black carbon (soot) particles; scattering best for large particles
- Green (532 nm) – measures in the visual range, typically what the human eye observes
- Blue (405 nm) – absorption correlates to the organic, or brown carbon content; efficient scattering for fine and ultrafine particles
| Parameter | Specification |
|---|---|
| Measured Parameters | Absorption coefficient, Babs Scattering coefficient, Bscat |
| Auxiliary Parameters | Temperature Pressure Relative Humidity |
| Derived Parameters | Black carbon (BC) mass Extinction coefficient, Bext Single scattering albedo, SSA Dew Point |
| Measurement Range – Absorption and Scattering | < 1 Mm-1 – 10,000 Mm-1 (870 nm, 60 sec. averaging) |
| Laser | 870 nm (1.4 W) Modulation Frequency: 1500 Hz nominal, square wave |
| Angular Integration for Scattering | 6° to 174° |
| Sample Flow | 1 L/min Flow Control: Critical orifice Diaphragm Pump |
| Response Time | < 10 sec; one-second resolution |
| Data Averaging Time | 1, 10 or 60 seconds, user selectable |
| Zero Check | On demand, or automated at user selectable interval at 5, 15, 20, 30, or 60 minutes. Zero check with high-efficiency filtered air sample. |
| Front Panel Features |
|
| Rear Panel Connections |
|
| Data Storage Capacity | > 200 days |
| Communications Output | Ethernet 100/10 Mbps, RS-232 Serial |
| Power Requirements | 90 – 264 V, 47 – 63 Hz (AC Power) or 12 VDC Power Consumption 45 W |
| Dimensions | 18 cm H x 48 cm W x 61 cm D (7" H x 19" W x 24" D); rack mountable |
| Weight | 18 kg (40 lb) |
| Environmental Operating Conditions | Temperature: 0 – 40°C (32 – 104°F) RH: 0 – 90% RH non-condensing |
| Computer Requirements for PMC Software (Computer not included) |
|
Hard-shell shipping case suitable for frequent travel
PM 1.0 cyclone inlet (1 liter/min) for particle size selection
PM 2.5 cyclone inlet (1 liter/min) for particle size selection
The Lifecycle Care Program ensures PAX integrity and performance vital to your research mission for 3 years or 3 calls (whichever comes first). When conducting complex and time intensive laboratory or field measurements it is critical to avoid down time, and ensure data collection accuracy. The program consists of 3 key deliverables for each year or call:
- Instrument Logistics
- Instrument Integrity
- Instrument Performance
Lifecycle Care Program Includes:
LOGISTICS
- Shipping to and from Droplet Measurement Technologies facility
- Customs handling, including CARNET ATA if required
INTEGRITY
- Incoming instrument evaluation and health check
PERFORMANCE
- Software and firmware validation
- 100%-unit functionality test
- Calibration data
- Calibration report
- Certificate of calibration
At times, our technician might discover an instrument issue, which might not be covered by the Lifecycle Care Program or by our product warranty. In such case we will reach out to you with a service & repair estimate to allow you to provide us with the next steps of action.
Characterizing elemental, equivalent black, and refractoryblack carbon aerosol particles: a review of techniques,their limitations and uncertainties
This review paper is designed as a guide for those wishing to learn about the current state of black carbon measurement instrumentation...
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Time-resolved measurements of black carbon light absorption enhancement in urban and near-urban locations of southern Ontario, Canada
In this study a photoacoustic spectrometer (PA), a laser-induced incandescence instrument system (LII) and an Aerosol Mass Spectrometer were operated in parallel for in-situ measurements of black carbon (BC) light absorption enhancement.
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On-road black carbon instrument intercomparison and aerosol characteristics by driving environment
A series of measurements was made comparing the performance of several different BC instruments (Single Particle Soot Photometer, Photo-Acoustic Soot Spectrometer, and Aethalometer) for high time resolution mobile measurements, capable of mapping spatial gradients.
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