Two different animals. The 'flame trap' is just north of the throttle body as you face the front of the car. Verify that the small diameter hose is clear of hard sludge and the plastic screen has been tossed in the garbage can.

The oil separator is under the intake manifold, slightly to the left of the oil dipstick. Replacement is about a 5 hour job and needs to be done at about 150K miles or so. Not for the level 1 mechanic. Look on matthews volvo site for a pictorial on how to do - Google it.