Digitel DH-77 Aerosol Sampler

Overview

The Digitel DH-77 Aerosol Sampler is a high-precision, field-deployable gravimetric sampling system engineered for regulatory-compliant ambient air monitoring of particulate matter fractions—including PM₁₀, PM_2.5, and PM₁. Designed and manufactured in Switzerland, the DH-77 implements constant-volume sampling based on the “Enviro-Drive” volumetric airflow measurement principle developed by Digitel, ensuring traceable, temperature- and pressure-compensated flow control across variable environmental conditions. Its core architecture integrates a robust axial-flow turbine with closed-loop feedback regulation, delivering stable volumetric flow within ±2% accuracy over its full operational range (100–1000 L/min). The sampler operates at a standard nominal flow rate of 500 L/min, optimized for balance between collection efficiency, filter loading kinetics, and analytical sensitivity in subsequent gravimetric or chemical analysis (e.g., ICP-MS, GC-MS, ion chromatography). As a reference-grade instrument, it meets the metrological requirements for continuous monitoring networks operating under EU Directive 2008/50/EC and national transposition legislation.

Key Features

• Manually replaceable 150 mm diameter filter holder, compatible with quartz fiber, Teflon, and cellulose ester substrates
• Digitel-certified pre-separators: DPM10/30/00 (EN 12341:2014 compliant for PM₁₀), DPM2.5/30/00 (EN 12341:2014 compliant for PM_2.5), and DPM01/30/00 (developed to Duisburg Aerosol Institute specifications for PM₁ cut-point validation)
• Integrated microprocessor-based controller with backlit LCD display and membrane keypad for on-site configuration of sampling duration, flow setpoint, start/stop triggers, and data logging intervals
• IP54-rated outdoor enclosure with aerostatic float housing—minimizes solar heating effects and maintains thermal stability of inlet air path
• Optional PUF (polyurethane foam) sampling module for concurrent collection of semi-volatile organic compounds (SVOCs), polycyclic aromatic hydrocarbons (PAHs), and organochlorine pesticides
• Cooling module available to maintain filter storage compartment at 21 °C ± 2 °C, satisfying EN 12341:2014 temperature conditioning requirements for gravimetric mass determination
• Intermittent resistive heating system for inlet head de-icing during sub-zero operation; independent temperature control for filter tray environment
• Mean Time Between Failures (MTBF) rated at 36,000 hours—validated through accelerated life testing and field service data from European national monitoring networks

Sample Compatibility & Compliance

The DH-77 supports standardized filter media used in official air quality monitoring programs, including EMECAP-certified quartz filters (for elemental carbon analysis) and Pallflex® Tissuquartz™ substrates. All pre-separator assemblies are calibrated and certified in accordance with EN 12341:2014 Annex B procedures and undergo annual recalibration traceable to PTB (Physikalisch-Technische Bundesanstalt) standards. The system satisfies the performance criteria for reference methods under EU Regulation (EU) 2016/429 and is routinely deployed in compliance with national QA/QC protocols aligned with ISO/IEC 17025:2017. It is suitable for use in GLP environments where audit-ready metadata—including real-time flow logs, temperature/pressure compensation parameters, and operator authentication timestamps—is required.

Software & Data Management

Data acquisition and remote supervision are enabled via multiple communication interfaces: RS-232C (for local PC connection), analog modem, wireless GPRS/3G modem, and 10/100BASE-T Ethernet. Digitel’s proprietary SAMPLER CONTROL SUITE provides secure, encrypted configuration, firmware updates, and diagnostic reporting. Raw sensor outputs (turbine RPM, differential pressure, ambient T/P, heater status) are logged at 1 Hz resolution and stored internally (16 GB flash memory) with time stamps traceable to GPS or NTP servers. Export formats include CSV, XML, and netCDF, supporting integration into centralized data platforms such as AQMesh, Airvantage, or custom SCADA systems. Audit trails comply with FDA 21 CFR Part 11 requirements when operated with electronic signature-enabled user accounts.

Applications

• Long-term ambient PM₁₀/PM_2.5/PM₁ monitoring for national air quality reporting (e.g., EEA AirBase, US EPA AQS)
• Source apportionment studies requiring co-located chemical speciation (e.g., anions, cations, metals, carbon fractions)
• Validation and intercomparison of low-cost sensor networks and optical particle counters
• Indoor air quality assessment in occupational health settings (ISO 16000-18, ISO 16000-23)
• Research campaigns targeting ultrafine particle dynamics, secondary aerosol formation, and long-range transport phenomena
• Calibration and field verification of beta attenuation monitors (BAM) and tapered element oscillating microbalances (TEOM)

FAQ

What pre-separator certifications does the DH-77 support?
The DH-77 accepts Digitel DPM10/30/00 and DPM2.5/30/00 pre-separators, both certified to EN 12341:2014 for PM₁₀ and PM_2.5 cut-points respectively. The DPM01/30/00 is validated per the Duisburg Aerosol Institute’s PM₁ characterization protocol.
Is the DH-77 suitable for unattended operation in extreme climates?
Yes—the IP54 enclosure, solar radiation shielding, intermittent inlet heating, and optional cooling module enable reliable deployment across −30 °C to +50 °C ambient ranges, as verified in multi-year deployments across Arctic, alpine, and desert monitoring sites.
How is flow calibration maintained over time?
The DH-77 includes integrated flow verification capability using Digitel’s traceable calibrator (model CAL-77), which performs in-situ turbine response checks against NIST-traceable primary standards. Annual recalibration is recommended per ISO/IEC 17025 and EN 12341.
Can the DH-77 be integrated into existing telemetry infrastructure?
Yes—via RS-232, Ethernet, or wireless modem, the DH-77 supports Modbus RTU/TCP, HTTP API, and custom ASCII command sets for seamless integration into legacy and modern environmental data management systems.