Tank Vent Valves install in the top surface of the fuel tank are designed to control vapors generated during the diurnal cycle (daytime/nighttime expansion and contraction of fuel).
In older (non-vented fuel fill) installations, they may also direct excess tank vapors generated during the fueling process.
Vent lines from TVVs generally run to carbon canisters to absorb any emitted fuel vapors.
Properly installed, TVVs also help protect the carbon canisters from contact with liquid fuel.
Perko TVVs are sometimes referred to as rollover valves (since they offer rollover protection), and as grade vent valves.
They also include an overpressure relief feature.
These valves mount in the surface of the fuel tank.
Mounting options for tank mounted TVVs include flanged (for plastic tanks), threaded (for metal tanks) and swivel (for both plastic and metal tanks).
• Flanged valves match the SAE 5-bolt level sender flange (Gasket is not included)
• Threaded valves mount with a 1" NPTF thread
• Swivel valves include valve, valve housing, O-ring, snap ring and tank insert
• Internally mounted versions are available for both plastic and metal tanks on a custom basis; please call 800-426-6930 for details
Heavy on the technical side...
Vent orifice: 0.091"
Airflow Rate Positive Pressure @ 0°F: 3.5 kPa > 10 l/min and 10 kPa > 18.2 l/min
Airflow Rate Positive Pressure @ 180°F: 7 kPa < 0.2 l/min and 13 kPa > 1 l/min
Re-opening pressure > min. 7 kPa
Maximum fuel leakage: < 1.5 cc/min @ 6 kPa pressure