Latest hose technology helps rail industry meet new European standard

15 February, 2017

In September 2013, a new European standard EN45545 was introduced for rail vehicles that sought to increase the protection for train passengers and staff in the event of a fire on board. New trains built from March 2016 onwards have to be in line with this new standard. With hoses used extensively throughout rail vehicles such as locomotives, high-speed trains and trams, achieving early compliance was crucial.

It is no secret that the rail rolling stock industry is among the world’s most demanding in terms of the pressures placed on components and systems used, particularly considering the extremes of vibration and temperature that are present in typical operating environments.

Calls for greater survivability

With the advent of trends such as higher speed trains and longer tunnels, the calls for greater survivability in the event of fire led the EU to seek an alternative to the plethora of rail industry standards that previously existed at a national level. Here, with cross-border rail travel abundant throughout Europe, manufacturers and operators had little choice but to meet each individual standard, at elevated time and cost.

Instead, the EU set about creating a single standard that would help ensure the implementation of a safe rail system across the continent. The first outcomes of this 20-year project emerged in September 2013 with the publication of the EN 45545 fire safety standard. However, there are important additions to the new EN 45545-2 standard which demand close attention. For example, nearly every component on a train that weighs in excess of 100g is now subject to testing.

Compliance

So, what are the principal applications for hoses in the rail industry, and what features are demanded of them to ensure compliance with the new EN 45545-2 standard? Well, one of the most notable demands concerns the burning behaviour of materials and components, where products are classified into various hazard levels.

For instance, EN 45545-2 contains specific requirements for: oxygen index to EN 4589-2; smoke density to EN 5659-2; and smoke toxicity to NF X70-100-1 and -2. For classification, the standard divides materials intended for installation into different areas (R22 inside/R23 outside) and three hazard levels (HL1, HL2, HL3), with HL3 being the highest. Furthermore, hose assemblies that are installed within hydraulic/pneumatic circuits that are deemed essential for the running capability of the vehicle have to pass a flame test in accordance with EN 15540 (a minimum of 800degC for at least 15 minutes), while another demand which has to be met to ensure compliance is the maintenance of pollutant emissions within very strict limits.

The fire behaviour of materials and components is not only dependent on their inherent properties, but their application, the shape and arrangement of the materials, the exposed surfaces, and the relative mass and thickness of the material. On this basis, the products listed in EN 45545-2 are further categorised into sub-groups according to: use in accessible or not openly accessible areas (such as the driver’s cabin); general area of application (inside or outside); and specific area of application (furniture, electrical equipment, mechanical equipment).

The operation and design categories according to EN 45545-1 are used to determine the hazard levels on which the requirements are based. This part specifies the test procedures, test conditions and requirements for each hazard level in terms of fire behaviour. These requirements are currently specified in 25 levels (R1-R25).

Test methods

The test methods are set out in detail. For example, lateral ‘spread of flame’ tests must be performed on vertical hanging samples in accordance with EN 5658-2, while the determination of optical density (smoke) must take place in a single chamber test complying with EN 5659-2. Further stipulations include the determination of the heat release and mass loss rate (cone calorimeter method) according to EN 5660-1, and testing for evidence of smoke toxicity according to NF X70-100 parts 1 and 2. There is also EN 11925-2 ignition testing for small parts and burning, dripping materials.

In the case of Parkers products, such tests are performed by certification company LAPI. The target for hose products is always to achieve high flame resistance through the use of special rubber compounds and the latest processing technologies. The principle of work is to operate as a development partner with customers to ensure hoses are safe, reliable, durable and flexible, and also offer trouble-free handling.

Parker is an experienced partner for rail applications and is certified to all required standards. The company has developed a wide range of hoses from low to high pressure for all relevant rail applications within locomotives, high speed trains, city trains, regional trains, trams, suburban trains/metros and track maintenance vehicles to meet the requirements of EN 45545-2. Parker is one of the first hose manufacturers to fulfil these new requirements in all classes.

Advantages

There is a strong demand for EN 45545-2 compliant hoses as mass transportation grows in importance and demand in many countries throughout the world is high. In Parker’s case the key to the success of many projects is the fact that Parker was the first hose manufacturer in Europe to develop a new rubber compound to the required standards of EN45545 in terms of fire retardancy, smoke behaviour and toxicity. The hose also delivers advantages such as a better bend radius to support easier design in and manipulation and assembly cost savings.

Hoses can be supplied for many rolling stock applications, including hydraulics (brake system, hydrostatics), pneumatics (brake system, suspension, auxiliary systems), cooling systems (water cooling, air conditioning), fluid conveying (diesel fuel, water for sanitary facilities) and heating (water).

Among the solutions available is the 681DB 2TE hose and 441RH compact hose, both of which feature carbon steel and stainless steel fittings. Also offered is the 477RH compact hose for very tight bend radii and the 421RH for large dimensions (up to 2”). In addition, the 372RH three-wire braid compact hose is designed for high pressures (4SP-level), while the 797RH Compact Spiral is suitable for applications where both high pressures and tight bend radii are required. All feature Parkrimp No-Skive crimping technology for those that prefer to make their own safe and reliable hose assemblies.