Case Study: SCADA Expansion for Radon and Carbon Gas DetectionClient: Chemical Manufacturing FacilityIntegrator: BONNER (Instrumentation, Controls & Safety Specialists)
Overview
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Background and Project Objectives
Following a site-wide risk review, the client identified the need for continuous monitoring of airborne hazards, specifically radon and CO and CO₂, to enhance worker protection and demonstrate compliance with Irish regulatory obligations. The existing SCADA platform previously provided by BONNER served as a strong foundation for adding environmental gas monitoring capabilities.
BONNER was engaged to design and implement an integrated expansion that would allow the facility to:
- Incorporate real-time radon monitoring, trending, and alarms.
- Implement CO/CO₂ detection with graded alarms, evacuation signalling, and optional ventilation interlocks.
- Provide traceable reporting aligned with EPA radon requirements and HSA Chemical Agents CoP.
Regulatory anchors used by BONNER during design:
Radon: Workplace reference level 300 Bq/m³, EPA workplace radon protocol, and S.I. No. 30/2019. BONNER emphasised that continuous monitoring supplements statutory measurement rather than replacing it.
CO/CO₂: Irish OELVs (CO: 20 ppm TWA / 100 ppm STEL; CO₂: 5,000 ppm TWA / 9,000 ppm 15-minute reference period) used to design conservative alarm thresholds.
2. Scope of Works Delivered by BONNER
2.1 Engineering and Design
System Architecture
BONNER designed an architecture enabling seamless integration of radon and CO/CO₂ detectors into the facility’s SCADA using a combination of:
- 4–20 mA / 1–10 V analogue devices, and
- Modbus RTU gateways for digital detectors.
Network segregation, secure OT–IT demarcation, and NTP-based timestamp alignment were implemented to ensure reliable alarming and traceability. Historical exposure data is now stored in the central historian.
Gas Detection Sub-Systems
Radon:
BONNER selected continuous radon monitors with both analogue and digital outputs, diagnostic routines, and dual averaging windows. SCADA logic developed by BONNER applies rolling averages, long-term trend smoothing, and alarm delays to avoid nuisance alarms. EPA measurement protocol steps, including placement rules, seasonal adjustments, and retest cycles, were embedded into BONNER’s reporting workflow.
CO/CO₂:
Industrial-grade transmitters, tested to the EN 45544 series, were installed.
Alarm Strategy and Cause & Effect
BONNER established a two-stage alarm philosophy for each gas type:
Stage 1 – Advisory/Warning
Stage 2 – High/Trip (with optional interlock)
Evacuation beacons, sounders, and SCADA annunciation were installed. Ventilation fans and dampers can now be automatically activated under high alarm conditions through hardwired interlocks.
All alarms were rationalised according to ISA-18.2, a process BONNER uses routinely to reduce operator overload and improve alarm quality.
HMI and SCADA Graphics
BONNER upgraded the SCADA graphics package to include:
- Floor-plan layouts with detector positions
- Trend and status views
- Device health/diagnostics indicators
Exposure dashboards showing:
- CO/CO₂ 8-hr TWA and 15-min STEL
- Radon daily/weekly/monthly averages vs 300 Bq/m³
This allowed operational teams and EHS staff to see exposure patterns instantly.
Data, Reporting, and Compliance
BONNER developed a suite of reporting tools, including:
- Monthly automatic exposure reports
- Alarm exceedance and event logs
- Evidence packs supporting EPA radon compliance (historical measurements, seasonal adjustments, remediation follow-up)
- Documentation aligned with HSA Chemical Agents CoP
Installation Engineering
BONNER designed the placement of all detectors using:
- Gas behaviour principles (buoyancy, diffusion, air patterns)
- EN 45544-4 installation guidelines
- Chemical-resistant materials, IP-rated enclosures, and ISA-5.1 labelling
Cybersecurity Baseline
BONNER implemented secure user management, change tracking, and backup/restore functions to align with the facility’s OT cybersecurity requirements.
2.2 Field Hardware and Panels
To support the SCADA expansion BONNER supplied and installed:
- Additional I/O cards and protocol gateways
- Audible/visual beacons
- Local acknowledgement/reset stations
- Interface relays for fan/damper control where required
2.3 Documentation Delivered
BONNER prepared complete engineering documentation, including:
- URS addendum for radon and CO/CO₂ detection
- Detector schedules, alarm setpoints, and full Cause & Effect matrix
- Updated GAs, layouts, and wiring schematics
- FDS/SDS covering scaling, communications, diagnostics, event timestamping, historian tags, and user roles
- FAT/SAT/commissioning test packs
3. Standards and Compliance Framework
BONNER delivered the system in accordance with:
Radon: EPA workplace protocol, S.I. No. 30/2019, 300 Bq/m³ workplace reference level
Toxic Gas Detection: EN 45544-1/-2/-3 (performance), EN 45544-4 (selection and installation)
Additional reference frameworks: ISA-18.2 (alarm management), ISA-5.1 (instrumentation labelling), EN 50271 (software-based detection systems)