Digitel DHA-80 Automated Filter-Changing Aerosol Sampler

Overview

The Digitel DHA-80 Automated Filter-Changing Aerosol Sampler is a high-reliability, field-deployable ambient air monitoring instrument engineered for long-term, unattended gravimetric sampling of atmospheric particulate matter. Based on the principle of isokinetic filtration under precisely controlled volumetric flow conditions, the DHA-80 continuously draws ambient air through interchangeable filter media—typically quartz fiber or Teflon®—while maintaining metrological traceability to international reference standards. Its core architecture integrates a robust environmental enclosure, a microprocessor-controlled carousel mechanism, and a thermally stabilized airflow path, enabling stable operation across extreme climatic gradients—from sea-level urban sites to high-altitude alpine stations such as Jungfraujoch (3278 m ASL), where the first unit entered service in 1972 as part of Switzerland’s National Air Pollution Monitoring Network (NABEL). The system complies with EN 12341 requirements for PM₁₀ and PM_2.5 measurement and supports optional PM₁ sampling via the DPM01/30/00 inlet, developed per specifications from the Institute of Energy and Environmental Technology (IUTA), Duisburg.

Key Features

• Automated 15-position filter carousel enabling uninterrupted 14-day sampling campaigns without manual intervention
• Precision mass-flow controlled aspiration with closed-loop regulation (100–1000 L/min), calibrated and verified per DIGITEL’s “Enviro-Drive” methodology for volumetric air sampling
• Integrated DPM10/30/00 and DPM2.5/30/00 pre-separators certified to EN 12341; DPM01/30/00 available for ultrafine particle fractionation
• Climate-resilient outdoor housing rated IP54, featuring passive solar radiation shielding, interval heating for frost mitigation, and independent temperature control of the filter storage chamber
• Optional PUF (polyurethane foam) sampling module for concurrent collection of semi-volatile organic compounds (SVOCs), polycyclic aromatic hydrocarbons (PAHs), and other vapor-phase analytes
• Cooling module maintaining filter storage at 21 °C ± 2 °C, conforming to EN 12341 thermal conditioning requirements for gravimetric analysis
• Modular 19-inch rack-mount chassis compatible with industrial data acquisition infrastructure

Sample Compatibility & Compliance

The DHA-80 accommodates standard 150 mm diameter filters—including quartz, cellulose ester, and fluorinated polymer substrates—selected based on analytical end-use (e.g., elemental carbon quantification via thermal-optical analysis or ion chromatography). All inlet configurations are validated against European reference methods: PM₁₀ and PM_2.5 cut-points are certified per EN 12341 Annex B, with aerodynamic performance verified using wind tunnel testing and cascade impactor intercomparison. For regulatory reporting under EU Directive 2008/50/EC or US EPA PM_2.5 FRM/FEM protocols, the DHA-80 serves as a compliant reference-grade sampler when paired with NIST-traceable flow calibrators and gravimetric balance workflows adhering to ISO 12103-1 and ASTM D1317. Its design supports GLP-compliant audit trails when integrated with time-stamped metadata logging and secure remote diagnostics.

Software & Data Management

Local operation is managed via an integrated membrane keypad and backlit LCD interface, supporting user-defined sampling schedules, flow setpoints, and event-triggered filter changes. All operational parameters—including real-time flow rate, pressure drop across the filter, ambient temperature/humidity, and carousel position—are logged internally with millisecond timestamp resolution. Data export occurs via RS-232C serial link, analog modem, wireless GPRS modem, or TCP/IP Ethernet—enabling seamless integration into centralized SCADA platforms or cloud-based environmental data management systems (EDMS). Firmware supports configurable alarm thresholds (e.g., filter clogging, power failure, temperature excursion) with automated SMS/email notification via connected modems. Raw logs comply with FDA 21 CFR Part 11 requirements when deployed with electronic signature-enabled software extensions and audit trail activation.

Applications

• Long-term trend analysis of PM mass concentration in national air quality networks (e.g., EEA AirBase, US EPA AQS)
• Source apportionment studies requiring co-located, multi-fraction aerosol samples for chemical speciation (ICP-MS, GC-MS, XRF)
• High-altitude background monitoring in remote or pristine environments (alpine, polar, marine boundary layer)
• Validation of optical remote sensing instruments (e.g., lidar, sun photometers) through collocated gravimetric reference measurements
• Regulatory compliance monitoring for industrial emissions, construction sites, and urban traffic corridors
• Research on secondary aerosol formation kinetics under controlled diurnal and seasonal forcing

FAQ

What is the maximum continuous unattended sampling duration?
Up to 14 days, assuming 24-hour operation at 500 L/min and use of all 15 filter positions.

Can the DHA-80 be used for PM₁ sampling?
Yes—when equipped with the DPM01/30/00 inlet, which has been characterized per IUTA Duisburg specifications for 1 µm aerodynamic diameter cut-point.

Is flow calibration traceable to national standards?
Yes—the Enviro-Drive volumetric measurement system is calibrated using primary-standard dry gas meters traceable to METAS (Swiss Federal Institute of Metrology) and NIST.

Does the system support remote firmware updates?
Firmware upgrades are performed via secure FTP over Ethernet or modem connection, with version rollback capability and SHA-256 integrity verification.

What maintenance intervals are recommended?
Routine inspection every 6 months; annual full calibration of flow sensor, temperature/humidity sensors, and carousel positioning accuracy per DIGITEL Service Manual DM-DHA80-SV-2.3.