DIN Standards Committee Railway
Safety evaluations of air-conditioning systems with flammable refrigerants in rail vehicles
Abstract
Railway air conditioning systems (BKS) are used for the air conditioning of driver- and passenger compartments and for battery conditioning. In normal operation as intended, the air conditioning system heats, cools and ventilates the driver's and/or passenger compartment in accordance with the specified requirements for air conditioning, or the air conditioning system regulates the temperature of the battery system. This document applies to mainline railway vehicles and urban railway vehicles. This document is applicable if ready-to-use refrigeration units with flammable refrigerants of class A2L, A2, A3 according to ISO 817:2014 are operated for air conditioning in rail vehicles. The systems shall be designed to be permanently technically sealed. The operation of the chiller for air conditioning includes heat pump operation. This document specifies procedures for recording and assessing hazards due to leaks in refrigeration circuits with flammable refrigerants that can occur during operational use, as a result of incorrect handling, technical defects or accidental events. The risk assessment in the life cycle with the anticipated operating modes is recorded by the OMRA (Operational Mode Risk Assessment), in which methods such as HAZOP (Hazard and Operability Analysis), FMECA (Failure Mode, Effects and Criticality Analysis) or FTA (Fault Tree Analysis) or a combination of these methods are used. Based on this, this document defines specific and targeted procedures and principles for risk identification on CCS and risk management as well as the associated validation steps and procedures. Taking into account DIN EN 50126-1 (VDE 0115-103-1):2018 10 and DIN EN 50126-2 (VDE 0115-103-2), this document specifies requirements for the air conditioning system, the vehicle manufacturer and the operator responsible for the use of flammable refrigerants. The following minimum requirements are also described. These are: - Carrying out a risk analysis in relation to leakages of flammable refrigerants; - Identification of risks over the entire life cycle and includes, for example, rolling and stationary operation, as well as railway-specific service and maintenance, recycling and decommissioning; - Implementation of risk-minimising measures in design and construction. The document also specifies requirements for the validation and verification of possible safety concepts and protective devices, including refrigerant leakage tests, dispersion simulations and functional tests of the associated protective devices. This document therefore already fulfils the procedural requirements of the CSM. The focus here is on hazards that may arise in the event of a leakage of flammable refrigerant, as the established system technology already comprehensively fulfils the safety requirements.
Begin
2023-03-28
Planned document number
DIN 27165
Project number
08701611
Responsible national committee
NA 087-00-07 AA - Heating, ventilation, air conditioning
draft standard
Safety evaluations of flammable refrigerants in air-conditioning systems of rail vehicles
2023-08
Order from DIN Media
