Relocation of existing Ex installations vs Ex

Let me say I do have numerous Ex installations on my site, but due to reasons I have to move them to a new facility.
Shall I apply to new regulations, or I may use all installation as it is?
I would say this is the most frequent asked questions which we daily face…
In the new facility it shall be considered as a new installation. This installation shall comply with latest regulations. At least the manufacturer shall confirm compliance to it in an updated DoC – at least! Most of cases it is not enough – this specially goes for non electrical Ex installations. Here again you may face situation becoming manufacturer.
Keep up good work!