UIC Leaflet 574: Standards for Thermally Insulated and Refrigerated Wagons

What is UIC Leaflet 574?

UIC Leaflet 574 is the international standard titled “Insulated and refrigerated wagons – Characteristics and testing.” It establishes the technical framework for vehicles designed to transport perishable goods across the global rail network.

The leaflet ensures that these specialized wagons possess the necessary thermal efficiency to maintain cold chains over long distances and through varying climatic zones. It is closely linked to the ATP Agreement (Agreement on the International Carriage of Perishable Foodstuffs), providing the railway-specific application of those international rules.

Technical Categories of Wagons

UIC 574 distinguishes between different types of temperature-controlled rolling stock based on their cooling capabilities:

• Insulated Wagons (Category IN/IR): Wagons with insulated walls, roof, and floor, but without a cooling or heating device. They rely on the thermal mass of the cargo and the quality of the insulation.
• Refrigerated Wagons (Category R): Wagons equipped with a cooling system (mechanical or using consumables like dry ice or liquid CO2) to lower and maintain the internal temperature.
• Heated Wagons: Wagons equipped with heating devices for goods that must be protected against extreme cold.

Thermal Efficiency and the K-Value

A core requirement of UIC 574 is the determination of the Heat Transfer Coefficient, commonly known as the $K$-value. The leaflet mandates specific testing procedures to measure this value:

• Normal Insulation: $K \le 0.7$ W/(m²·K).
• Heavily Insulated: $K \le 0.4$ W/(m²·K).

Testing involves placing the wagon in a temperature-controlled chamber and measuring the energy required to maintain a temperature difference between the interior and exterior over a set period.

Standardized Markings and Lettering

To facilitate rapid identification by yard personnel and health inspectors, UIC 574 requires specific Wagon Markings:

• The Blue Snowflake/Ice Crystal: Standard symbol for refrigerated or insulated capacity.
• Category Codes: Lettering indicating the level of insulation and the type of cooling equipment.
• Service Dates: Clear indication of the last thermal efficiency test and the expiration of the ATP certification.

Comparison: Insulated (IN) vs. Refrigerated (R) Wagons