5 Measuring gases

5.1          A number of surveys have revealed undeclared gases carried in CTUs. Many of the gases are dangerous and would constitute a severe risk to those involved in unpacking.

5.2          The person who controls the opening and entry of CTUs should always check the chemical properties and the threshold limit value (TLV) of the relevant chemical, referring to their own national standards and guidelines where they exist.

5.3          Unfortunately, one cannot rely on ones sense of smell as most of these gases will be well above their TLV by the time they can be detected. The only practical way is to take air samples. In the open this is very difficult. Initially, a device that identifies the gas is required before the concentration of the gas can be measured.

5.4          The simplest and easiest way to measure the internal atmosphere is to use a readily available detector tube device. Do not open the CTU but gas can be sampled by forcing a solid tube in through the door gaskets (see figure 5.21).

Figure 5.21 Sampling gas

5.5          There is no device available that can detect all hazardous gases, therefore one measurement will not provide sufficient information about the internal atmosphere and multiple tests will be required.

5.6          The risk of hazardous gases in CTUs is relevant to all parties in the supply chain. The causes of these gases can be attributed to internal business processes in manufacturing or by actions performed on behalf of third parties (service providers and logistics companies).

5.7          Action plans for testing and reacting to hazardous gases in CTUs may be drawn up by companies to protect their employees from the effects of these gases when opening and unpacking them. The companies producing the actions plans may not be the ultimate consignees of the goods, but may be authorized to open the CTU earlier in the supply chain or responsible for unpacking.

5.8          It should be remembered that hazardous gases may be introduced into the CTU by:

• Deliberately adding gases to prevent deterioration of the goods by pests;
• Emissions of substances used in the manufacture of products or dunnage;
• Chemical or other processes in the cargo.

5.9          In addition, incidents may occur that permit the release of gases from declared or undeclared dangerous goods being carried.