Overview of Test Methods for Insulation Performance of Passive Cold-Chain Insulated Containers (Part 1)

Cold-chain transportation is a product of scientific and technological advancements in the logistics industry, deeply intertwined with people's daily lives. Unlike conventional logistics, cold-chain logistics typically requires significant investment. However, the application of passive refrigerated containers has dramatically reduced the capital needed for cold-chain transport. Verifying the performance of these passive refrigerated containers is essential to ensure they effectively maintain temperature control and safeguard product integrity throughout the transportation process. Meanwhile, China's cold-chain logistics sector faces prominent challenges, including weak infrastructure, lack of standardized protocols, and inadequate regulatory oversight. Below, we’ll outline relevant aspects—specifically focusing on transportation packaging testing and pharmaceutical packaging testing.

Introduction to Domestic and International Validation Specifications and Standards for Passive Insulated Cold Chain Containers

The Ministry of Health's No. 90 Order, the "Good Supply Practice for Pharmaceutical Products" (commonly known as Pharmaceutical GSP), officially came into effect on June 1, 2013, establishing comprehensive management guidelines—along with corresponding pharmaceutical packaging testing principles—for pharmaceutical companies, including drug manufacturers and enterprises involved in the storage and transportation of pharmaceuticals. Later that same year, in November, the national standard titled "General Specifications for Cold-Chain Insulated Boxes for Pharmaceuticals," approved by the National Standardization Administration Committee and spearheaded by the National Technical Committee for Logistics Standardization, underwent drafting, research, discussion, revision, and refinement before being officially released for public consultation on the organization's website.

The international standards ASTM D3103, Standard Test Method for Thermal Insulation Performance of Distribution Packages, ISTA 7E Testing Standard for Thermal Transport Packaging Used in Parcel Delivery System Shipment, and ISTA 7D Temperature Test for Transport Packaging each provide regulations with distinct focuses on validating insulated packaging. These standards serve as valuable reference guidelines for testing and verifying pharmaceutical packaging used in cold-chain insulated boxes.

Currently, China lacks unified standard guidelines for implementing specific testing and verification procedures on pharmaceutical packaging using cold-chain thermal containers. Instead, most enterprises and institutions rely on repeated trial-and-error approaches, followed by real-world distribution tests, to determine optimal container designs, dimensions, the quantity and placement of refrigerants, as well as pre-treatment temperature and duration—among other critical factors. As a result, the entire pharmaceutical packaging testing process ends up being excessively lengthy, leading companies down unnecessary detours and wasting significant resources in the process.

Introduction to the Test Method for Thermal Insulation Performance of the "General Specifications for Pharmaceutical Cold Chain Insulated Containers"

In practical use, the thermal insulation performance of cold chain insulated boxes needs to be periodically tested through random sampling inspections of pharmaceutical packaging. This standard outlines two types of inspection protocols: type testing and factory inspection. Type testing is primarily conducted when a new cold chain insulated box design is introduced, during the transition of production to a different facility, or after the official start of production for pharmaceutical-grade cold chain boxes—specifically when there are changes in the box’s structure, materials, manufacturing processes, or any other requirements that could potentially affect the product’s performance. It’s also required if production of a particular model has been halted for over one year before resuming. Additionally, routine annual sampling inspections are carried out during regular production. On the other hand, factory inspection focuses on random checks of finished products at the time of shipment to ensure compliance with pharmaceutical packaging standards.

The test samples should be representative, and sampling must be conducted through random inspections. The general pharmaceutical packaging testing standards for cold-chain thermal insulation boxes include specific guidelines for testing the box's thermal performance, and the basic steps of the pharmaceutical packaging test are illustrated in Figure 1.

The standard requires that refrigerated drugs or simulants, along with the test objects, be pre-treated to reach the specified storage temperature prior to packaging integrity testing. Once at the required temperature, the treated drugs or simulants should be placed inside an insulated box. Temperature sensors must then be carefully installed at the center of the box, as well as on the upper and lower sides and adjacent lateral positions. Additionally, frozen cold packs should be positioned around the product within the box—specifically at the top, bottom, and sides—and it’s crucial to ensure these cold packs are separated from the drugs/simulants and the temperature recorder by appropriate dividers. Finally, the box is sealed, and the insulated container is placed in the designated test environment for the prescribed duration, during which time the packaging integrity test is conducted while data is continuously recorded. A temperature logger must also be used to monitor the real-time temperature conditions throughout the entire testing process.

The temperature recording equipment used in pharmaceutical packaging testing must undergo temperature deviation verification, with the maximum allowable error specified in Table 1. The sensors used for verification must also be calibrated and verified, and their maximum allowable error values are listed in Table 2. During the operation of pharmaceutical cold-chain thermal containers, the temperature monitoring devices for pharmaceutical packaging should update measurement point data at least once every minute and record temperatures at least once every 5 minutes. If the monitored temperature exceeds the specified range, the system must log real-time data at intervals of no more than 1 minute. Additionally, the alarm function is an essential component throughout the entire thermal performance testing of the container; the guidelines stipulate that when the monitored temperature reaches or surpasses the designated range, the pharmaceutical packaging testing temperature monitoring equipment must notify at least three personnel.

The thermal performance of incubators used for pharmaceutical packaging testing is significantly influenced by the external test environment. To address this, regulations specify the environmental conditions for incubator thermal performance tests on pharmaceutical packaging, as outlined in Table 3. This table provides examples of various combinations between insulation duration and ambient temperature conditions. However, during actual transportation, the external temperature of incubators can fluctuate widely depending on seasonal and regional factors. Moreover, these temperature changes often occur gradually or even in alternating patterns. Therefore, developing precise temperature profiles for pharmaceutical packaging tests still requires extensive practical experience across industries and individual companies.