NPTF Threaded Fill Limit Valve - 3/8" Airspace

These valves are for use on fuel tanks to comply with the CARB and EPA standards and meet the requirements of USCG Safety Standards.

The Fuel Fill Limit Valve is used to establish ullage (air space) in the tank to help prevent overfilling.
The FLV incoproates a small float mechanism which, as the tank is filled, rises to seal off air escaping through the vent line. (See accompanying diagram.) When the float rises and air can no longer escape, pressure builds in the tank and fill hose, and is sensed by the pressure shut-off mechanism in the dockside fuel pump.
To prevent fuel vapors escaping into the atmosphere, the vented air from the tank is ported via a 5/8" hose back to the receiving 5/8" hose barb on a vented fuel fill fitting.

Note:   FLVs do not connect to carbon canisters — those deal with vapors generated by thermal expansion, not refueling.

Fuel Fill Limit Valves mount in the top surface of the fuel tank.
Mounting options for tank mounted FLVs include flanged (for plastic tanks), threaded or welded (for metal tanks), and swivel (for metal tanks).

These NPTF threaded valves mount into a 1” NPTF dry seal threaded aluminum receiver which is welded to the top surface of the aluminum tank. The receivers are sold separately and are not available through Fisheries Supply.

Distant sensing (DFLV) versions are available for both plastic and metal tanks on a custom basis.


Heavy on the technical side...

Note: The ullage depth is set by the tank manufacturer or OEM builder and cannot be changed. In order to maintain compliance with the EPA and CARB requirements, these valves that set the ullage depth cannot be interchanged with different depth valves.
Custom ullage set points are available. Contact us at 800-426-6930 for details

Flow > 70 l/min @ 0.25 kPa
Flow without corking @ 130 l/min
Minimum reopening pressure: 0.5 kPa