Introduction: The Critical Need for Real-Time Oxygen Monitoring in Hydrogen Systems
As industrial sectors integrate hydrogeninto energy systems, fuel processing, and chemical manufacturing, real-time oxygen monitoring becomes increasingly critical. Oxygen, when present in hydrogen mixtures above threshold limits (~2–4%), can render the gas flammable or explosive. Therefore, precise, continuous, and reliable oxygen measurement is vital for risk mitigation and compliance with global safety standards.
Traditional gas analysis approaches—based on sample extraction and conditioning—pose serious concerns when applied to high-concentration hydrogen streams. This is especially true when hydrogen concentrations exceed 30%, where the risk of leakage, material degradation, and explosion escalates significantly.
Hydrogen Characteristics and Measurement Risk Factors
Hydrogen presents a unique set of challenges to gas measurement systems:
- Small molecular size: Hydrogen molecules can permeate through elastomers and small imperfections in fittings.
- High diffusivity and flammability: With an LFL (~4%) and extremely low ignition energy (~0.02 mJ), hydrogen is inherently hazardous.
- Hydrogen embrittlement: Hydrogen exposure weakens metallic materials, especially under high pressure and cyclic loading.
- Rapid Gas Decompression (RGD): Non-metallic seals can crack under pressure cycling, leading to leakage.
These properties make sample extraction from hydrogen-rich environmentsinherently risky, especially when relying on components like dynamic seals, relief valves, or atmospheric vents.
Regulatory Standards and Design Constraints
A convergence of international safety standards now advises against or restricts the use of traditional sample extraction equipment in hydrogen systems:
OSHA 29 CFR 1910.103 (Hydrogen)
- Mandates welded or brazed jointswherever possible.
- Requires valves, gauges, and fittings to be explicitly rated for hydrogen service.
API Specification 6D – Annex M (2025 Update)
- Introduces “Specification Level for Hydrogen” (SLH 1–4).
- Requires:
- Leak tests under hydrogen
- RGD testing for elastomers
- Fugitive emissions certification
- Fire-safe designs
- For SLH2+, dynamic seals and PRVs are discouraged unless fully qualified.
ISO 19880-1:2020 / ISO 19880-9:2024
- Governs hydrogen fueling system design.
- Emphasizes in-situ sensors, dead-leg elimination, and air ingress avoidance.
NASA / AIAA Hydrogen Design Guidelines
- Forbid PTFE/elastomers in direct hydrogen service unless tested.
- Ban atmospheric PRVs unless flared or inerted.
- Recommend metal-to-metal jointsand enclosed architectures.
Sample Extraction Limitations in Hydrogen Environments
Designing a gas sampling system for hydrogen involves trade-offs:
Leak Risk
Even properly assembled fittings and seals may leak due to embrittlement or seal degradation—a critical danger in flammable mixtures.
Rapid Gas Decompression (RGD)
Elastomeric seals suffer cracking under sudden pressure drops. This failure mode is addressed in ISO 23936-2 and NORSOK M-710.
Contamination and Purging Complexity
Sample lines require inert gas purgingbefore every cycle, adding complexity, maintenance overhead, and room for human error.
Compliance Burden
Meeting modern hydrogen standards (SLH2+, ISO 19880) necessitates expensive certified components, often impractical at scale.
In-Situ Oxygen Analysis as a Viable Alternative
To overcome these risks, industries are shifting to in-situ oxygen analyzers, which:
- Are installed directly in the gas stream
- Use metal-to-metal or welded static connections
- Avoid dynamic seals, purge valves, and sample conditioning
Modcon’s Advanced In-Situ Gas Analyzers
Modcon Systems Ltd., based in London, introduces a non-extractive solution with two flagship products:
MOD-1040 Optical Oxygen Analyzer
- Based on quenched fluorescence
- High-precision, contact-free oxygen measurement
- Designed for pressures up to 200 barg, KOH-resistant
- Certified ATEX/IECEx, rated SIL-2
MOD-1060 Thermal Conductivity Hydrogen Analyzer
- Measures hydrogen in binary gas mixtures
- Operates reliably under variable conditions
- Compatible with corrosive, high-pressure environments
Together, these process gas analyzersenable sensor fusion for enhanced accuracy.
Real-Time Optimization with AI-Driven Control
Modcon’s solution goes beyond measurement. It embeds analyzers into Modcon.AI, a deep reinforcement learning (DRL) system for autonomous optimization:
- Real-time ingestion of gas, voltage, temp, and pressure data
- Adaptive control over electrolyzer power, water feed, and pressure
- Learning model adjusts for power source variability and wear
Fusion Modeling and Digital Twin Integration
Modcon leverages digital twin technology and hybrid modeling:
- Combines electrochemical simulations, ML models, and mechanistic predictors
- Provides virtual replicas of electrolyzer stacks
- Enables predictive diagnostics and pre-emptive control
Advantages of In-Situ Monitoring
Compared to traditional extraction systems, in-situ analyzers provide:
- Improved safety: No hydrogen venting
- Real-time interlock support
- Smaller footprint
- Lower maintenance and OPEX
- Simpler compliance with OSHA, ISO, and API standards
Shaping the Future of Green Hydrogen
By removing the need for sample extraction and enabling real-time gas analysis, Modcon is solving the core bottleneck in green hydrogen production:
- Scalable across electrolyzer designs
- Environmentally sustainable through energy optimization
- Cost-effective due to minimal infrastructure
CEO Perspective
“As the global demand for clean hydrogen surges, process intelligence and safety are no longer optional—they are foundational,” said Gregory Shahnovsky, CEO of Modcon Systems Ltd. “By uniting advanced sensors with intelligent control systems, we’re not just improving hydrogen production—we’re making it economically and environmentally sustainable at scale.”
About Modcon Systems Ltd.
Founded in 1972 and headquartered in London, Modcon Systems Ltd. is an innovative multidisciplinary company with its own technologies of process analysis and AI-enabled optimization for process industries. Today, Modcon is leading the charge in developing the next generation of process analyzer systems, setting new standards for innovation and efficiency in the Oil Refineries, Natural Gas, Pipelines, Chemical, Petrochemical and Biotechnology Industries. The company provides:
- Online process analyzers
- AI-enabled process optimization systems
- Advanced green hydrogen production solutions
Modcon is accelerating the transition to a smart, safe and decarbonized energy future.
