When a spill berm fails under pressure or a decontamination pool leaks hazardous runoff, the root cause is often hidden in plain sight: a zipper that was never designed to withstand hydrostatic load, chemical exposure, or field conditions. Traditional “water-resistant” closures rely on coatings or overlays that crack, delaminate, or permit seepage when liquid presses against them. For environmental response OEMs, industrial safety manufacturers, and remediation contractors building containment systems, the difference between a sealed barrier and a liability comes down to one engineered component—the zipper.
Lenzip’s airtight, chemical-resistant, RF-weldable zippers are purpose-built for spill berms, oil-spill barriers, decontamination pools, chemical dikes, and mobile containment. Each closure integrates TPU or PU-coated tapes that RF-weld directly to coated fabrics, creating a continuous membrane with no stitch perforations. Verified through leak testing, hydrostatic pressure trials, chemical immersion studies, UV exposure, and abrasion cycles, these closures deliver the pressure-rated, field-durable performance that containment applications require. U.S.-owned • Minimums as low as 25 units.
Containment Needs a True Pressure Seal
Why “Water-Resistant” Zippers Leak Under Hydrostatic Load
“Water-resistant” usually describes resistance to surface moisture—rain or splash. In containment, liquids apply hydrostatic pressure (head) that increases with depth. A decon pool filled to 300 mm applies force perpendicular to every seam and closure; a berm holding diesel exerts head pressure that exploits coating micro-defects and stitch holes. Closures designed for atmospheric conditions permit penetration when pressure builds.
Airtight vs. Water-Resistant—Engineer Takeaways
- Airtight closures are rated for pressure hold (PSI/bar) with zero measurable leakage over a defined interval; water resistant may pass spray/immersion yet leak under head.
- Conventional water resistant zippers can fail around ~1–3 PSI; pressure-rated airtight designs maintain zero leakage at ~10–14 PSI or higher, subject to construction.
- For berms governed by EPA secondary containment (40 CFR 264.175), poor sealing risks non-compliance and environmental discharge.
Method alignment: see Zipper Testing Standards and How to Read Zipper Spec Sheets.
RF-Welded Membranes—No Stitch Holes
Sewing introduces hundreds of needle perforations; even with seam tape, thread channels wick fluid, and flexing degrades the seal. RF welding fuses thermoplastic zipper tapes to coated substrates without adhesives, producing a homogeneous, liquid- and air-tight joint. Compatible materials include TPU, PU, and selected vinyls.
Why RF-welded zipper interfaces hold up
- Stitch-free seam removes leak paths.
- Molecular bonding creates a joint often stronger than the base fabric.
- Process control (power/dwell/pressure) yields repeatable peel/shear strength across lots.
Operator guidance: Integrating Zippers into RF-Welded or Heat-Sealed Seams.
Chemical-Resistant Materials & Coatings
TPU vs. PU for Fuels, Oils, Solvents, Disinfectants
Not all liquids are equal. Selecting the right coating maintains mechanical properties and sealing integrity after contact.
- TPU (polyether & polyester grades): broad resistance to mineral/lubricating oils, gasoline, biodiesel; strong low-temp flexibility; good UV stability.
- PU: cost-effective protection for moderate acids/alkalis and select solvents in controlled environments.
- Caveats: Strong acids/bases and chlorinated solvents may require special formulations or alternative constructions.
We supply compatibility matrices (media, concentration, dwell) to dial the right tape/fabric pair.
System Materials That Prevent Secondary Failures
Bring this forward so spec readers don’t miss it:
- Low-wick polyester tapes minimize capillary fluid travel along the closure.
- Corrosion-safe sliders/stops (stainless or zinc-free alloys; optional polymer stops) reduce binding and contamination under salt, bleach, or acidic runoff.
- Coating carry-over across tracks reduces metal-to-fluid contact and debris entrapment.
Quick refs: Zipper Material · Zipper Gauge & Chain Size Chart
Tested for Field Reality
PSI Leak-Hold & Burst Verification
Laboratory testing translates claims into thresholds. For airtight closures, the key metric is leak-hold pressure: the maximum sustained pressure with zero leakage over the hold time.
- Representative reporting: 0 cc/min at 10 PSI for 60 s (pressure-decay or bubble method).
- Burst testing should show 2–3× operating pressure margins; preferred failure mode is base fabric, not weld or teeth.
Final ratings depend on fabric stack-up and weld window; we confirm during prototyping and FAIs.
Hydrostatic Head (ASTM/ISO)
Hydrostatic head (ISO 811 / AATCC 127) measures resistance to liquid penetration under a rising column.
- Unit clarity: 2,000 mmH₂O ≈ 2.8 PSI; 3,000–5,000 mmH₂O (≈ 4.3–7.1 PSI) generally covers 300–600 mm fill depths with margin for slosh/spikes.
- We test complete assemblies (fabric + weld + zipper) for system-level decisions.
UV, Abrasion, Salt/Humidity, Cold-Crack
- UV (ASTM G154): ≥ ~1,000 h with ≥ 80% strength retention indicates robust stabilization.
- Abrasion (ISO 12947-2 / ASTM D4966): 10k–25k Martindale cycles without fray/delam/teeth damage.
- Salt fog (ASTM B117): stainless/zinc-free hardware resists binding/corrosion.
- Cold-crack (ASTM D2136): polyether TPU variants retain flexibility down to ~−30 °C.
RF-Weldable Integration to Coated Fabrics
Compatible Substrates
- Bonds readily to TPU-laminated and PU-coated textiles; selected flexible PVCs (plasticizer-dependent).
- Non-polar plastics (PE/PP) do not RF-weld—use adhesives or mechanical methods.
Weld Window & Seam Geometry (Quick Notes)
- Control power, dwell, pressure for full-depth fusion without surface burn-through.
- Typical seam overlaps 15–25 mm for containment; avoid sharp corners; double-track welds enable non-destructive air-channel checks.
- Test frequency: at least per lot or parameter change; log peel/shear, visuals, and pressure checks.
Process details: Integrating Zippers into RF-Welded or Heat-Sealed Seams.
Common Applications
Spill Berms & Chemical Dikes
Portable berms capture leaks per 40 CFR 264.175. Airtight zippers enable rapid deployment and reconfiguration; head pressure can increase sealing force by pressing the interface closed.
Oil-Spill Barriers & Decon Pools
Marine booms face wave/current/salt; TPU-coated closures resist petroleum distillates and corrosion. Decon pools demand closures that tolerate bleach, detergents, solvents, foot traffic, and thermal cycling.
Mobile Containment & Temporary Storage
Bladder tanks and catch basins need tool-free access while maintaining pressure and liquid-tightness. Zippered systems store flat, deploy fast, and adapt to variable site geometry.
Explore related industries: Safety · Outdoor Gear · Fabric Structures · Tents
Engineering Support & Compliance
- Datasheets & CAD (DXF/STEP) with dimensions, tolerances, and property data.
- SDS & batch traceability tied to raw-material certs and QC pulls.
- REACH/RoHS documentation for global supply chains.
- Cleaning/maintenance SOPs: rinse after exposure; dry thoroughly; apply silicone-safe lubricant sparingly; inspect weld edges, sliders, terminations.
Reference hubs: Zipper Testing Standards · How to Read Zipper Spec Sheets
Seal Your Containment Spec with Lenzip
Send your fabric, fluid/media list, and target PSI/head. We’ll return a spec-matched zipper construction (gauge, TPU/PU tape, slider/hardware), a starting RF weld window (power/dwell/pressure), and a QC checklist (peel/shear + leak/decay) you can hand to production. U.S.-owned • Engineering support • Minimums as low as 25 units.
Request a Chemical-Resistance & PSI Spec Match
Quick help: Customer Support
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Frequently Asked Questions
Will these zippers hold pressure in a liquid-filled berm?
Yes—airtight, pressure-rated designs are validated to hold hydrostatic loads (e.g., 0 cc/min at ~10 PSI for containment, up to ~14 PSI for specialized builds), with burst margins verified at the assembly level.
Which chemicals are supported and at what concentrations?
TPU: fuels, lubricants, biodiesel; PU: moderate acids, alcohols, select solvents. Strong acids/bases and chlorinated solvents may require alternate constructions. Ask for our compatibility matrices.
Can we RF-weld to our TPU/PU/vinyl fabrics?
Yes for TPU/PU and select PVCs (verify plasticizer load). Run pre-production weld trials to confirm peel/shear targets. PE/PP requires an alternate attachment.
What weld strength numbers should we target?
Typical containment acceptance: peel ≥ 100–150 N/25 mm, shear ≥ 150 N/25 mm, with base-fabric failure preferred over interface failure.
How do UV and abrasion impact long-term sealing?
With stabilized coatings, expect ≥ 80% strength retention after ~1,000 h UV; 10k–25k abrasion cycles without functional loss is a solid benchmark. Inspect/lube per SOP.
What maintenance is recommended after chemical exposure?
Rinse, brush debris, dry fully, apply silicone-safe lube, and inspect seams/slider/terminations before redeploying.