A gas concentration control device for pressure vessel is provided for controlling gas concentration inside an accommodation space that is set in an interior of a chamber formed inside a pressure vessel curing oven. The connecting device has a first and a second coaxial connector and a coupling member. A data warehouse system collects customer data from the customer web sites and stores the data at a data warehouse server. The channels 40 can extend in a generally longitudinal direction of the block 14. With the method of the present invention, the chlorinated alkane product has covalently bonded thereto at least one more chlorine group than the chlorinated alkane substrate, and the chlorinated alkane substrate and the chlorinated alkane product each have a carbon backbone structure that is in each case the same.