Overview of Test Methods for Insulation Performance of Passive Cold-Chain Insulated Containers (Part 2)

ASTM D3103 Introduction to the Testing Method

This pharmaceutical packaging testing method outlines the thermal barrier quality of drug packaging products and the thermal stability of their contents when exposed to various external environmental conditions. It is applicable to packaging containing a wide range of internal energy sources. The basic procedure for pharmaceutical packaging testing is illustrated in Figure 2.

Sensor calibration

In ASTM D3103, the data acquisition unit for pharmaceutical packaging testing consists of single- or multi-channel recorders, along with accompanying software and hardware systems. These systems use thermocouples and resistance temperature sensors—developed in collaboration with the National Institute of Standards and Technology—to collect data that tracks changes in temperature over time. The device boasts a resolution accuracy of at least 0.1°C, while the temperature measurement error during pharmaceutical packaging tests remains within ±0.5°C.

Sampling and Sample Requirements

The samples used for pharmaceutical packaging testing include the insulated containers whose performance is being evaluated, as well as the actual contents and phase-change materials (PCMs) used during real cold-chain transportation. During pharmaceutical packaging tests, efforts should be made to ensure that the samples closely resemble real-world conditions. If the actual samples cannot be obtained, substitute materials may be used—provided that these substitutes closely match the original samples in terms of quality, specifications, properties, and structural characteristics.

At least three samples should be used for pharmaceutical packaging testing to ensure the reproducibility of the results. In each sample, the pharmaceutical packaging system—including its components, quality units, and positioning—must be assembled identically. Additionally, the total mass, layout, and surface area of the cold-storage medium or phase-change material source must remain consistent. Finally, the contents of the effective payload inside the insulated container should be evenly distributed across all temperature zones within the box.

Environmental Handling and Sensor Installation

Before conducting packaging tests on pharmaceutical products, it is mandatory to pre-condition all packaging materials, refrigerants, and the product itself according to ASTM D4332. This pre-conditioning process must last for at least 24 hours—or as specified by particular requirements—while ensuring that different components are treated under conditions tailored to their individual needs. Importantly, these pre-conditioning settings must align precisely with the specific testing criteria. The purpose of temperature pre-conditioning in pharmaceutical packaging testing is to use the minimum amount of cooling agent necessary, thereby maintaining the temperature inside the insulated container within the required range—neither falling below nor exceeding the specified limits—for the duration of the actual transportation period.

Before pre-processing, if feasible, the probes should be directly attached to the inner walls of the primary packaging and to the products inside. When installing the probes, ensure that their accuracy and temperature-reading capability remain unaffected. The number of probes typically depends on the size and quantity of the primary packaging under the payload. For the initial evaluation of insulated packaging, at least 5 to 10 probes are required to monitor up to 25 primary packaging systems within the payload, as illustrated in Figure 3, which shows a schematic diagram of the sensor and phase-change material system used for validating the insulated packaging during pharmaceutical packaging testing. During pharmaceutical packaging tests, make every effort to minimize the risk of heat transfer through the wires connected to the sensors.

Test Requirements

After sealing the incubator, place it in a controlled environment for testing. During pharmaceutical packaging tests, the orientation of the incubator should match the actual direction of transportation. Additionally, packaging materials must not come into contact with the walls or floor of the test chamber, and there should be at least 6 inches (150 mm) of space between each packaged item. Throughout the testing process, continuously monitor and record temperatures at various points within the packaging until either the internal temperature inside the box exceeds or falls below the specified target range, or until the predetermined test duration is reached.

During pharmaceutical packaging testing, the temperature-time curve conditions for the exterior of the thermal container typically include actual ambient temperatures collected during the test, regulatory requirements, contractual specifications, and a constant temperature setting. The standard for pharmaceutical packaging testing specifies that the method for collecting actual temperatures can refer to the test protocol outlined in Ista 5B: Focused Simulation Guide for Thermal Performance Testing of Temperature-Controlled Transport Packaging.

After the pharmaceutical packaging testing, the report must include basic information such as the package dimensions, structural features, materials used, and sealing methods. It should also contain diagrams showing the distribution of energy-supplying substances within the packaging, as well as visualizations of insulated packages and the placement of thermocouples or other sensors. Additionally, the report should detail the type and quantity of refrigerants and internal packaging components, specify the temperature data acquisition system employed, outline the procedures for loading and handling packaging materials prior to testing, document the ambient temperature and relative humidity during the test, note the total duration of data collection, indicate the remaining amount, temperature, and physical state of the refrigerant at all times, and finally, describe the physical condition of the product inside the package at the end of the experiment.

A comparative introduction to ambient temperature conditions

Currently, the temperature environment curves used during pharmaceutical packaging testing for cold-chain thermal insulation box performance vary widely depending on the specific conditions. While the "General Specifications for Pharmaceutical Cold-Chain Insulation Boxes" provides reference guidelines for recommended insulation durations and corresponding ambient temperature combinations, ASTM D3103 focuses more on outlining the testing methodology itself. In contrast, ISTA 7D offers detailed external temperature profiles tailored to different transportation scenarios, providing invaluable guidance for both insulation box manufacturers and users when conducting performance tests. For instance, Table 4 of ISTA 7D clearly defines the alternating test conditions for a 72-hour international air express delivery, with the corresponding temperature curve illustrated in Figure 4.

Within our country, many companies also maintain a variety of internal environmental standards. As shown in Figure 5, one company has developed an empirical temperature curve for testing the thermal insulation performance of its cold-chain insulated boxes—specifically tailored for pharmaceutical packaging. This curve reveals that domestic Chinese enterprises often impose even stricter temperature conditions for pharmaceutical packaging tests compared to those outlined in ISTA 7D. For instance, their maximum test temperature reaches 42°C, while the lowest can dip as low as -20°C. At the same time, establishing temperature-time profiles based on seasonal variations (spring, summer, autumn, winter) and transportation modes (land, sea, air) represents a relatively sound approach. Currently, China’s Packaging Research and Testing Center has already developed a logistics monitoring device capable of continuously tracking real-time data on temperature, humidity, vibration, and impact during transit. This innovative tool provides crucial technical support for gathering accurate temperature data in cold-chain logistics environments and for studying the unique characteristics of different transportation methods.

The sensor calibration project aligns precisely with the requirements outlined in Appendix 5 of the Pharmaceutical GSP, "Verification Management," specifically regarding the validation of pharmaceutical packaging testing and monitoring systems. Additionally, ASTM Standard D3103 provides a more detailed methodology for verification, making it a valuable reference for domestic standards related to thermal insulation box validation. In terms of sensor installation and refrigerant placement, ASTM D3103 offers a more meticulous and comprehensive approach, ensuring that the recommended placement methods accurately assess the thermal performance of the insulated boxes. While China’s Pharmaceutical GSP already includes clear guidelines for developing cold-chain insulated boxes, there remains a notable gap in the country: the lack of precise and reliable testing methods to evaluate the insulation performance of these boxes during pharmaceutical packaging. Extensive experimentation has revealed that factors such as the quantity, positioning, quality, and volume of refrigerants significantly influence the internal temperature of the insulated boxes. Moreover, the accuracy of the temperature monitoring system—and the strategic placement of its probes—are critical prerequisites for ensuring the reliability of test results.

Cold-chain thermal boxes are now widely used in the food and pharmaceutical industries, yet incidents of supply chain disruptions due to inadequate insulation performance remain all too common. As a result, China urgently needs to establish standardized testing and validation criteria for the thermal performance of cold-chain thermal boxes specifically tailored for pharmaceutical packaging. These standards should align with the guidelines outlined in the Pharmaceutical GSP and introduce a set of practical, effective verification methods. This will not only provide robust design guidance for cold-chain thermal boxes but also help reduce transportation costs, ultimately driving the growth of China's cold-chain logistics sector.