For quality control and development of advanced products it is not only necessary to know the actual gas pressure within the VIP but it is also important to measure the change of gas pressure.

Previous measurements took a long time to get reliable results. Therefore va-Q-tec has developed several methods which allow to obtain information on the increase of gas pressure within a short time and thus to perform accelerated ageing tests.

In even a shorter time it is possible to reduce the increase of gas pressure by accurate thermal conductivity measurements of a VIP-sample containing a special core material. From the known relation between the thermal conductivity and the gas pressure of the core material the gas pressure increase can be calculated. An example with VIP containing a special core material and wrapped in a metallized film cover is shown in Fig. 4. Here the measurement took just one day and a clear increase of thermal conductivity, which is proportional to the increase of gas pressure, can be seen.

These methods help va-Q-tec to control the barrier properties of delivered films, the gas pressure of any produced VIP and to develop new kinds of vacuum insulation products.