On Wed, 29 Apr 2009 15:05:37 +0100, Frank Erskine
wrote:

Don't forget that compression fittings are BSP sized, therefore the
correct spanners will (or should be) imperial size.

I did wonder that when I measured 28.5mm but then I thought if the
pipe is metric, surely the fittings will be too; I was forgetting that
15 and 22 mm pipe are essentially 1/2 and 3/4 inch pipe.