An MVFuse is a SVRS (Safety Vacuum Relief System) It is a vacuum break that senses an unsafe rise in system suction vacuum and opens to allow air to vent the line to avoid body and some forms of limb entrapment if a person was to block a suction line.
An MV fuse comes in two forms. One is a device that fits on top of the In-Deck Debris canister. The other is in a 6-inch deck canister of its own that can be used for safety from entrapment of any drain attached to it.