On Wed, 24 Aug 2005 17:01:06 +0100, Sue Beans wrote:

I've tried unscrewing the screw to open up the ring

When it runs out of thread, it won't loosen anymore. If you really
need to split the ring open, pull it apart by hand.

As others have said, this isn't something that should be on the inlet,
unless the installer had made a bodge of course.

--
Nigel M