Refrigerated vans carry everything from delicate tropical flowers to deep frozen foods. Keeping the box at just the right temperature requires the right reefer unit and the best van body for the job.

The thermal capabilities of a refrigerated van body can make all the difference when protecting perishable goods. Today, most refrigerated trailers are insulated with polyurethane foam because it is lightweight, cost effective, versatile during the manufacturing process and allows for a wide variety of applications. While polyurethane initially provides excellent insulating performance, as a trailer ages, the foam can lose its ability to insulate effectively.

One way to prevent this is to use a less permeable interior liner. However, the liner of choice for the North American market is fiberglass reinforced plastic (FRP), which is permeable and does not completely seal the insulation, allowing an “out gassing” effect to occur. A better alternative is to use FRP with the sealing ability of a metal skin.

The ideal refrigerated van trailer is one that combines the flexibility of polyurethane with a glass-reinforced, thermoplastic liner. This solution preseals the trailer’s insulation, which enhances the insulation’s thermal efficiency and helps maintain excess cooling capacity. This advantage means a reduction in cooling unit run-time and more fuel savings.

A thermoplastic liner is important because as the lightweight polyurethane foam insulation is injected into the walls, floors and ceilings, it is subject to a chemical reaction. During this process, insulating gas in the foam expands and is retained in the cell structure of the polyurethane. Over time, some of the cell gas escapes from the foam and air migrates into the cells.

As more of the insulating cell gas escapes and air gets into the cells, and enters if the trailer is damaged, or there is moisture intrusion or air loss, the polyurethane foam loses its insulating capacity. When insulation performance suffers, longer cooling unit run-times are required to make up for the loss of thermal efficiency.

To reduce cooling unit run time and fuel consumption, Great Dane’s ThermoGuard refrigerated van trailer addresses the thermal degradation that occurs in polyurethane foam insulation. According to the trailer maker, ThermoGuard can also lower operational costs by cutting maintenance and repair needs. It also extends the useful life of the refrigerated trailer.