Safe use of flammable refrigerants in rail HVAC systems

Climate regulations and net-zero targets are driving the adoption of sustainable refrigerants. These include flammable refrigerants such as R290 (propane) which are gaining traction due to their low global warming potential (GWP = 3) and energy efficiency. R290 contributes to slow emissions of greenhouse gases accounting for global warming. It also has characteristics favourable for HVAC adoption.

However, such refrigerants also have high flammability (Class A3) which introduces safety risks. This requires rigorous design and testing protocols to ensure safe operation and handling throughout their use as rail HVAC refrigerants. TÜV SÜD offers holistic services that include inspection, risk analysis, technical reports, and training.

Safety

Operators must reduce the fire and explosion risks of flammable refrigerants. R290 needs leak detection systems, explosion-proof enclosures, and crew training.

Market growth

The rail HVAC refrigerants market is expected to grow at 6.8% CAGR by 2030, fuelled by retrofitting fleets with new builds such as Talgo ICE L, which uses R290.

Regulatory evolution

Standards such as DIN 27165 address flammability risks, but fragmented norms (e.g., EN 378-2, EN 60335-2-40) complicate compliance.

Material compliance

EN 45545-2 fire safety standards for materials add complexity, as flammable refrigerants demand strict flame-retardant components.

Regulatory gaps

Existing standards (e.g., EN 45545 series) lack detailed guidelines for flammable refrigerant integration, creating compliance ambiguities.

System complexity

Ensuring leak-proof HVAC refrigerant systems in vibration-prone rolling stock requires advanced engineering (e.g., hermetic compressors, redundant sensors).

Cross-domain risks

Interactions between HVAC systems and other vehicle components (e.g., electrical systems, battery compartments) heighten fire hazards if not properly isolated.

Training costs

Training staff to handle flammable refrigerants during maintenance and emergencies is critical but resource-intensive.

Multi-regional compliance

Differing norms (e.g., EU TSI vs. U.S. FRA) force manufacturers to redesign systems for regional markets, increasing costs.

Lack of precedents

First-movers such as Talgo face uncharted risks, as R290 use in rail HVAC is novel, with limited case studies for reference.

TÜV SÜD is an independent inspection body for rolling stock, accredited according to ISO 17020. Our expertise includes Notified Body (NoBo), Assessment Body (AsBo), and Designated Body (DeBo) services across several countries.

This allows us to offer comprehensive safety assessment services for flammable refrigerants in accordance with Technical Specifications for Interoperability (TSI), urban rail regulations, and more. We monitor the entire process and increase effectiveness through interim evaluations of the ongoing process.

Our capabilities include legal and normative framework conditions to holistic system analyses. These span the entire HVAC refrigerants sector, assessing both products and their integration into vehicles. Our extensive project experience includes collaborations with industry leaders such as Faiveley/Wabtec and Liebherr.

Notably, we are responsible for the safety assessment of R290 products in the new Talgo ICE L, covering HVAC, galley refrigeration, and vending machines.

We are uniquely positioned as the only inspection body actively involved in developing DIN 27165, the forthcoming standard for flammable refrigerants in rolling stock. Our active role in shaping this standard ensure that its requirements align with real-world rail operational risks.

Additionally, we collaborate with in house experts working on other HVAC refrigerant units using flammable refrigerants in both, mobile (e.g., EN 17893, ISO 20854) and stationary applications. If needed, we can also leverage our explosion safety branch and in-house NoBo for pressure equipment directive (PED).

Our services include:

• Holistic risk assessments – Early-stage evaluation of HVAC refrigerant designs (e.g., leak detection placement, ventilation rates) via preliminary risk analyses and validation plans. Initially, we assess your preliminary risk analysis and collaboratively develop a validation plan. Subsequently, we review the provided documents, verify their accuracy, and conduct a final risk assessment. This process culminates in a technical report tailored to your needs. For first-time collaborations, we recommend this comprehensive service. For subsequent projects, we can streamline the process to save time and costs by generalising the validation plan and preliminary risk analysis.
• Systems integration assessment– Reviewing interactions between HVAC refrigerant units and vehicle systems (e.g., electrical safety, EN 45545-2 material compliance) to prevent cross-system failures.
• Training – We offer workshops ranging from broad overviews to detailed discussions on specific topics. We can tailor these to your specific requirements.
• Material safety – We can also assess material fire safety according to EN 45545-2.