Xsara HDI fuel filter - how to open???

[ebod]

Hi, does anyone with a HDI have any clever tricks to open up the fuel filter housing. Mine has three pipes on top with a sensor plug also. THe outer edge is ribbed suggesting this is a grip point to undo by hand.

But no amount of levering has got me anywhere at the moment.
I'm frightened of using the top nozzles to lever against as I'm sure I will end up snapping something.

There does not appear to be any hex head profile to use a wrench or socket with so I'm stuck right now.

any clues?
thanks

[JohnD]

Disconnect the inlet and outlet, then turn anticlockwise the ribbed outer ring whilst holding the centre still. You may need something like a big stillson or oil filter wrench to move it. Pack some rags beneath to catch spillage.