A vacuum bleeder off ers a number of advantages over a pressure bleeder:
An ability to remove the brake fl uid from the master cylinder by sucking it out of the filler. This means that fluid changes are far quicker as not all the fl uid needs to be bled via a nipple.
No need to have a pressure tight seal on those diffi cult to get to master cylinder reservoirs.
By “sucking” the fl uid away, risk of sudden spillage is signifi cantly reduced.