85Kr gas is encapsulated in welded titanium capsules with a 25 µm thick titanium window. Capsules are sealed either by cold welding a copper filling tube or crimping a silver washer. The crimped silver washer sources are only filled to sub atmospheric pressures. The inclusion of a welded back cap provides a secondary seal and improved mechanical strength. A protective window shield is included with each source to protect the window during transportation and handling. It also absorbs the beta dose from the source, making it easy for the user to handle and load into gauging devices.
Windows are Helium leak tested to <10-8 mBar l-1 sec-1 before filling.