The insulation layer serves as the "constant temperature barrier" of cold storage, and the selection of its materials directly determines the operational stability and operating costs of the cold storage. Material substitution is a common hidden danger during cold storage installation, with the replacement of polyurethane boards with EPS foam boards being the most typical case. While it may seem to reduce costs initially, it actually multiple risks for subsequent operations.

           Thermal conductivity is a core indicator of insulation materials, directly related to insulation performance. The thermal conductivity of polyurethane boards is usually ≤0.024W/(m·K), while that of EPS foam boards generally ranges from 0.045 to 0.055W/(m·K) — the thermal conductivity of the latter is nearly twice that of the former. In low-temperature cold storage environments, this difference leads to accelerated cold air leakage. The unit has to operate at full load continuously to maintain the set temperature, resulting in a significant surge in energy consumption; monthly electricity bills may increase by more than 30%.

          Insulation failure directly causes temperature fluctuations, which is devastating for cold chain storage. Low-temperature cold storage requires the temperature to be stably maintained at -18℃±0.5℃. EPS foam boards cannot form an effective insulation layer, and the temperature inside the cold storage is prone to fluctuations of more than ±3℃. This not only causes frozen products to repeatedly thaw and frost, damaging their cellular structure and affecting quality, but also accelerates food spoilage. The loss rate may rise from the normal 3% to over 10%.

         The physical stability of EPS foam boards is also far inferior to that of polyurethane boards. In low-temperature environments, EPS boards are prone to shrinkage and embrittlement, and cracks may appear in as short as 3 to 6 months, further exacerbating cold leakage. In contrast, polyurethane boards have high density and strong aging resistance. They can maintain structural stability for a long time in environments ranging from -40℃ to 60℃, with a service life of more than 10 years, far exceeding the 3 to 5 years of EPS boards.

Standards must be adhered to when selecting cold storage insulation materials. For low-temperature cold storage, polyurethane color steel plates with a density of ≥40kg/m³ should be used, and the thickness should reach 10-15cm according to the cold storage temperature requirements. After installation, an infrared thermometer should be used for testing to ensure that the temperature difference between the surface and the environment does not exceed 2℃. Only by eliminating the hidden danger of material substitution from the source can the core demand of constant temperature and energy conservation for cold storage be achieved.