6 Best Barrel Bungs For Evaporation Prevention

Securing stored liquids on a job site often falls to the wayside until evaporation or contamination ruins a project’s inventory. Whether dealing with solvent-based coatings, primers, or specialized adhesives, a drum that isn’t sealed tight is a drum losing money. Choosing the right bung is as critical as choosing the right fastener for a ridge cap. Get it wrong, and the resulting chemical imbalance can compromise the performance of your materials.

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Tri-Sure Steel Bung Plug: Best for Steel Drums

Steel drums remain the gold standard for high-durability storage in demanding construction environments. The Tri-Sure steel bung provides a precise, metal-to-metal fit that stands up to the heavy handling typical of warehouse loading docks and job sites.

When you are dealing with aggressive solvents or thinners, you need a closure that won’t degrade under chemical exposure. Steel plugs paired with proper gaskets ensure that volatile organic compounds stay inside the drum rather than venting into the air.

Avoid using plastic bungs on heavy-duty steel drums if you expect them to be stacked or moved by mechanical clamps. The structural integrity of the steel bung prevents deformation under pressure, ensuring the seal remains intact throughout the transit process.

Rieke VISEGRIP II Bung: Top for Hazmat Storage

Hazmat compliance is non-negotiable when storing paints, resins, or chemical cleaners on-site. The Rieke VISEGRIP II is engineered specifically to meet stringent shipping requirements, including those for flammable materials.

This bung features a unique design that offers extra security against accidental loosening during vibration or transit. If a drum is being hauled on a truck over uneven terrain, this type of closure provides the necessary insurance to prevent leaks.

Always verify that the bung’s material composition is rated for the specific chemical stored inside. While the design is robust, the gasket material must be compatible with the substance to avoid swelling or chemical degradation.

Solid Silicone Bung Plug: Best for Temperature Flux

Working through changing seasons means materials often expand and contract as temperatures swing. A rigid bung can lose its seal as the drum wall shifts, but a solid silicone bung offers the necessary flexibility to maintain a vacuum.

Silicone is inherently resistant to extreme heat and cold, making it ideal for job sites where drums are exposed to direct sunlight or freezing temperatures. It doesn’t become brittle like some plastics and provides a superior “memory” to snap back into a tight fit.

Use these for non-pressurized storage where you need to accommodate thermal expansion. They are often the best choice for protecting sensitive additives that might otherwise lose effectiveness if exposed to oxygen.

Mauser Plastic Bung: Ideal for Poly Drums

Polyethylene drums require specific closures that don’t bite into the plastic threads of the drum opening. The Mauser plastic bung is the industry standard for poly containers, offering a lightweight yet durable solution that won’t rust or corrode.

Plastic bungs are highly effective for storing water, mild detergents, or materials that would cause a steel bung to oxidize. They provide a clean, non-reactive interface that keeps the contents pure and prevents metal contaminants from entering the mix.

Ensure the bung is tightened only until firm. Overtightening plastic threads can strip the drum’s neck, leading to an impossible-to-seal opening that forces the retirement of an otherwise perfectly good drum.

Polypropylene T-Handle Bung: For Frequent Access

If you are regularly pulling small amounts of product—like primer or bonding agent—you need a bung that opens quickly without requiring specialized tools. The T-handle design allows for manual operation, which saves time during high-paced application tasks.

These are excellent for field use where carrying around a heavy bung wrench isn’t feasible or necessary. Because they are made from polypropylene, they offer decent chemical resistance for common construction liquids.

Use these only in environments where the drum is standing upright and unlikely to be subjected to high-impact external forces. The T-handle protrudes slightly, making it more susceptible to damage if the drum is dropped or struck.

Lever-Lock Rubber Bung: Best for Uneven Openings

Sometimes an older, dented, or non-standard drum opening presents a sealing challenge that a threaded plug cannot overcome. A lever-lock rubber bung expands to create a custom-fit pressure seal, regardless of minor imperfections in the bung hole.

This mechanism acts like a heavy-duty stopper, using a cam-action lever to compress a rubber ring against the interior wall. It is the go-to solution when you need to seal an opening that has been slightly warped by impact.

Inspect the rubber component regularly for dry rot or cracking, especially if the drum is kept outdoors. Once the rubber loses its elasticity, the seal is effectively broken and the unit should be replaced immediately.

Bung Material Guide: Steel vs. Plastic vs. Silicone

Material choice isn’t just about cost; it’s about longevity and chemical compatibility. Steel is the leader in structural strength, providing the best protection for drums that will be handled roughly.

Plastic is the lightweight, non-corrosive alternative perfect for water-based products. Silicone occupies the niche for thermal resilience and consistent sealing in volatile conditions.

• Steel: Best for flammables, heavy transit, and long-term industrial storage.
• Plastic: Best for non-corrosive chemicals, water-based coatings, and budget-conscious bulk storage.
• Silicone: Best for materials prone to reaction with oxygen or where extreme temperature shifts occur.

NPT vs. Buttress Threads: Match Bung to Your Drum

Mixing up thread types is a common mistake that leads to damaged drums and wasted product. NPT (National Pipe Taper) threads are common on steel drums and create a tighter seal as they are screwed in, due to their tapered design.

Buttress threads are wide, flat, and usually found on plastic poly drums. They are designed for quick engagement and are less likely to cross-thread, but they do not provide the same mechanical seal as a tapered thread.

Always check the drum manufacturer’s markings before ordering replacement bungs. If the threads don’t match perfectly, even the best gasket in the world won’t prevent a slow, steady leak.

Getting a Perfect Seal: Using a Bung Wrench Right

The right tool is the difference between a secure seal and a mangled bung. Use a dedicated bung wrench that fits the specific lug pattern of your plug; using a screwdriver or pliers is a recipe for stripped heads and rounded edges.

Apply firm, consistent pressure when tightening. Once the gasket makes initial contact with the drum surface, a quarter to half-turn is usually sufficient to seat the seal properly without damaging the threads.

Keep your bung wrench clean and free of grease or chemical buildup. A slipping tool on a pressurized or hazardous chemical drum creates unnecessary safety risks for everyone on the job site.

Bung Gaskets: Buna EPDM or Viton for Your Needs

The gasket is the true hero of the seal, yet it is often overlooked during procurement. Buna-N (Nitrile) is the standard for general-purpose oil and solvent applications, offering good elasticity and toughness.

EPDM is the superior choice for weathering, ozone resistance, and water-based chemicals, though it fails when exposed to petroleum-based products. If you are handling high-performance, exotic chemicals or intense fuel additives, upgrade to Viton.

Viton provides the broadest chemical resistance and the highest temperature rating, acting as a universal insurance policy for high-value materials. Investing in the correct gasket material for your specific liquid is much cheaper than cleaning up a spill or losing expensive product to evaporation.

Properly sealing your drums is a small but vital detail that prevents large-scale waste on the job site. Select your bungs and gaskets based on the chemical content and the environment, and your inventory will remain stable until the very last drop is used.