HEMRUNK Vented Transfer Tank Fuel Cap 2" NPT Thread - Diesel Tank Cap, Spring-Loaded Venting

HEMRUNK’s vented transfer tank cap is a direct-fit replacement diesel fuel cap with a 2" NPT threaded neck that vents tank pressure and prevents vacuum build-up.

This heavy-duty replacement cap is designed for transfer tanks, mobile fuel tanks and auxiliary diesel tanks that require a venting solution and a secure seal. It replaces common Fill-Rite/Dee Zee style caps, fits a 2" NPT threaded neck and combines a snug iron base with internal springs and seals so fluids stay contained while air can move freely in and out of the tank.

How does the HEMRUNK cap prevent over-pressurization or vacuum?

The built-in vent mechanism allows excess pressure to escape and permits air to enter as fuel is used, keeping tank pressure near atmospheric levels. This reduces stress on the tank body and plumbing and helps ensure consistent fuel flow to pumps or engines.

• Integrated venting releases pressure safely while in storage or transit.
• Air intake prevents vacuum that can hinder fuel delivery.
• Spring-actuated valve opens at set pressure differentials for reliable function.
• Designed to work with diesel and similar fuels without altering system operation.

Will this cap fit my existing 2" NPT transfer tank neck?

The HEMRUNK cap installs on a standard 2" NPT threaded neck and is intended as a replacement for many Fill-Rite and Dee Zee transfer tank caps. It includes an iron threaded base that seats into the tank neck for a secure mechanical fit.

• 2" NPT threads match common transfer tank plugs and adapters.
• Iron base provides a durable, tight fit to resist loosening under vibration.
• Works with most diesel and fuel-compatible tank openings designed for 2" NPT caps.
• Check thread type and diameter on your tank before ordering to confirm compatibility.

How simple is installation and removal for everyday use?

Installation is straightforward: align the cover with the groove, press down and rotate clockwise until seated. Removing the cap requires pushing down and turning counterclockwise, so routine fuel access is quick and tool-free for most users.

• Tool-free twist-and-lock operation for fast maintenance and refills.
• Positive alignment groove minimizes cross-threading during installation.
• Compression design with internal seals ensures leak resistance after each use.
• Sturdy construction resists wear from repeated removal and replacement.

What keeps the cap leak-proof while still venting?

HEMRUNK combines a snug-fitting iron neck with spring-loaded seals inside the cap that close against liquid while allowing gas to pass through the vent when needed. This arrangement limits fuel seepage but still equalizes pressure as the tank fills or empties.

• Spring-loaded valve seals against liquid intrusion yet opens for gas exchange.
• Rubber or elastomer seals resist fuel degradation and maintain a tight closure.
• Iron base provides structural rigidity for consistent sealing over time.
• Engineered to reduce drips and leaks under normal operating conditions.

Who this is for: The HEMRUNK vented transfer tank cap is aimed at fleet managers, contractors, farmers and vehicle owners who use portable diesel tanks, auxiliary fuel systems or weather guard-style mobile tanks. If you need a dependable, replaceable 2" NPT vented cap that balances secure containment with reliable venting, this cap offers a robust, easy-to-use solution for routine fueling and transport needs.