Engineered Coated Fabric & Membrane Supply
Project-specific membrane materials and fabricated panel directions for low-pressure biogas storage—built around the different jobs of the inner gas membrane, outer weather membrane and optional bottom sealing layer.
A double membrane biogas holder is a flexible gas-storage system commonly used between anaerobic digestion and downstream gas consumption, upgrading or energy-generation equipment. Its inner membrane changes with the amount of stored biogas, while an outer air-supported membrane maintains the holder's external shape and provides protection from weather.
The key purchasing point is that the two membranes do not have identical duties. The inner layer is primarily a gas-contact membrane, so low permeability, chemical resistance, flexibility and repeatable seam welding matter. The outer layer faces UV, rain, wind, snow and temperature cycling, so tensile performance, weathering and surface durability become more important.
For procurement teams, separating membrane roles early helps reduce the risk of over-specifying one layer while under-specifying another.
The outer envelope stays inflated by support air and protects the gas-storage membrane from the external environment.
Priority: UV stability, weathering, wind/snow load capability, tensile and tear strength, low-wick edge control and durable surface treatment.
Common direction: reinforced PVC-coated polyester with a PVDF or upgraded weather-resistant surface where specified.
The inner membrane expands and contracts with gas volume and remains in contact with methane-rich biogas and condensate.
Priority: low gas permeability, H?S/CO?/moisture resistance, controlled flexibility, seam integrity and repeatable welding behavior.
Common direction: gas-barrier PVC-coated polyester; alternative coating structures can be discussed for demanding conditions.
Some free-standing or dome configurations use a bottom membrane to complete the flexible gas envelope or interface with the supporting structure.
Priority: gas sealing, puncture and abrasion resistance, weld reliability, dimensional stability and compatible connection detailing.
Common direction: project-defined reinforced coated fabric matched to the floor, slab or anchor arrangement.
A useful RFQ for a double membrane gas holder does more than state diameter or capacity. Material selection improves when the supplier understands the complete operating envelope.
The ranges below are a practical starting point for technical discussion. Final values should be confirmed against the project drawing, gas composition, structural calculation, applicable standard and approved technical data sheet.
| Specification item | Inner gas membrane direction | Outer membrane direction | Why buyers should define it |
|---|---|---|---|
| Base reinforcement | High-tenacity polyester fabric | High-tenacity polyester fabric | Controls tensile, tear, dimensional stability and welded-panel handling. |
| Coating system | PVC gas-barrier direction; selected TPU option by project | PVC with optional PVDF / weather-resistant surface | Inner and outer layers face different chemical and weather exposures. |
| Typical weight direction | Approx. 900–1500 g/m2, customizable | Approx. 900–1500 g/m2, customizable | Weight is only one variable; yarn, coating and strength targets also matter. |
| Thickness direction | Project-specific; commonly around 0.9–1.5 mm for PVC directions | Project-specific; commonly around 0.9–1.5 mm for PVC directions | Should be tied to material structure rather than used as a stand-alone quality indicator. |
| Gas permeability | Low-permeability target defined by gas, test method and project requirement | Usually secondary unless outer layer also forms part of the gas envelope | Waterproof performance is not the same as methane-barrier performance. |
| Temperature direction | Common project discussion range: about -30°C to +70°C for selected PVC constructions | Common project discussion range: about -30°C to +70°C for selected PVC constructions | Low-temperature flexibility and heat aging should match the installation climate. |
| Flame-retardant option | Project-based DIN / EN / NFPA direction where required | Project-based DIN / EN / NFPA direction where required | Specify the exact test method and certificate requirement before production. |
| Welding process | HF/RF, hot-air or hot-wedge compatibility by formulation | HF/RF, hot-air or hot-wedge compatibility by formulation | Seam behavior is part of gas-tight performance and fabrication repeatability. |
| Supply format | Roll goods, cut sheets, fabricated panels or OEM specification supply | Roll goods, cut sheets, fabricated panels or OEM specification supply | Allows membrane fabricators and system builders to align supply with their workflow. |
Flexible low-pressure storage helps decouple continuous or fluctuating gas production from downstream use, subject to the plant's process design.
Livestock manure, slurry and crop-residue digestion systems where biogas is buffered before CHP, heating or upgrading.
Sludge digestion facilities requiring controlled storage between anaerobic digesters and gas utilization equipment.
Organic-waste and high-COD wastewater projects for food processing, breweries, distilleries and related facilities.
Process wastewater and organic residue treatment where methane-rich gas is collected for energy recovery.
Selected gas-management systems requiring flexible buffer storage as part of a broader collection and utilization train.
Buffer storage upstream or downstream of gas treatment, according to the pressure and purity requirements of the plant design.
A clear technical package helps DERFLEX discuss membrane structure, supply format and fabrication compatibility without relying on generic assumptions.
DERFLEX's core strength is the coated technical membrane layer: reinforced base fabric, coating structure, gas-barrier direction, weather-resistant surface, welding behavior and repeatable OEM supply.
Depending on the project and quotation scope, supply may include roll material, cut sheets or fabricated membrane panels. Blowers, pressure sensors, safety valves, control panels, structural calculations, anchors and installation engineering should be confirmed as separate scope items with the responsible system integrator unless specifically included in a written offer.
This scope-first approach helps EPC contractors and biogas equipment companies compare quotations on the same basis and reduces ambiguity during approval.
The choice is not simply “membrane is better” or “steel is better.” A double membrane holder is often attractive where the project benefits from flexible storage volume, relatively lightweight envelope construction and integration with low-pressure anaerobic-digestion systems. A rigid vessel may be preferred where the process requires a different pressure regime, mechanical protection or code pathway.
Testing should be tied to the buyer's specification and agreed methods rather than relying on broad marketing claims.
Verify reinforcement, coating uniformity, weight/thickness direction, adhesion and surface treatment against the approved specification.
Approve seam settings and peel/strength behavior using the fabricator's actual HF/RF, hot-air or hot-wedge process where possible.
Confirm the gas-permeability criterion, chemical exposure, UV/weathering expectation and any low-temperature requirement that applies.
Align TDS, color, roll width, batch identification, fire-test documents and packaging requirements before repeat production.
DERFLEX approaches a double membrane biogas holder from the technical textile outward—helping buyers define what the membrane must do before locking in weight, coating or surface finish.
Gas contact and outdoor exposure create different failure modes. DERFLEX can discuss separate material directions for each membrane position.
PVC, PVC/PVDF and selected TPU directions allow the material structure to be adjusted for gas barrier, UV, cleanability and fabrication requirements.
For repeat gas-holder programs, specification control, approved samples, roll identification and packaging can be aligned with the buyer's production workflow.
Six related DERFLEX pages help engineers and procurement teams narrow material choices for biogas storage and anaerobic digestion systems.
Inner, outer and bottom membrane roles for flexible low-pressure gas storage.
Material selection for methane containment, pressure movement and outdoor exposure.
Dedicated membrane-fabric page for double-envelope gas-holder systems.
PVC, PVDF and TPU material directions for digesters, holders and gas collection.
Gas-tight cover material for agricultural, municipal and industrial digestion.
Floating and supported membrane solutions for manure and wastewater lagoons.
Buyer-focused answers for EPC contractors, biogas equipment companies, wastewater engineers and membrane fabricators.
A double membrane biogas holder is primarily a flexible gas-storage system using an inner gas membrane and an air-supported outer membrane. A digester cover closes the digestion tank and may also provide some gas storage. Some projects combine both, functions in a tank-mounted double membrane roof, while others use a separate free-standing gas holder.
Reinforced gas-barrier PVC-coated polyester is a common material direction because it combines strength, flexibility and weldability. The final coating formulation should be matched to gas permeability, H?S and condensate exposure, temperature and the fabricator's welding process.
A PVDF or upgraded weather-resistant surface can be considered for the exposed outer layer where UV resistance, surface durability and cleanability are important. Whether it is needed depends on climate, life-cycle target and project budget.
DERFLEX's core offering is engineered coated membrane material and project-specific membrane fabrication support. Roll goods, cut sheets or fabricated membrane panels may be discussed. Blowers, control panels, valves, anchors, structural calculations and complete installation scope should be confirmed separately in the written quotation.
Capacity is determined by the system design rather than the membrane fabric alone. Double membrane holders can be engineered across a wide range of storage volumes, but the feasible size depends on geometry, pressure, wind/snow criteria, foundation or tank dimensions, anchoring and the complete control system.
Send the holder type, storage volume, tank diameter or foundation size, normal/design pressure, gas composition and H?S level if known, climate and wind/snow data, membrane layer required, welding method, fire-retardant standard, quantity, destination and any project drawings.
Send DERFLEX your storage volume, pressure range, membrane position, gas conditions, climate, welding method and drawings. We can discuss a project-matched coated-fabric direction and quotation scope.