The porous PTFE gas diffusion plate is a self-supporting hydrophobic microporous membrane manufactured from 100% PTFE dispersion resin through paste extrusion, calendering, high-temperature sintering and precision biaxial stretching. The process converts the resin into a fibril-node network of billions of interconnected pores, delivering an average pore size of 5 μm and porosity above 80% within a sheet only 0.2 mm thick and trimmed to a standard 100 × 100 mm square.

Because the carbon backbone of PTFE is fully shielded by fluorine atoms (C–F bond energy 485–532 kJ/mol), the material is intrinsically hydrophobic and chemically inert: the water contact angle exceeds 120° and the surface energy sits near 18–22 mN/m, so aqueous liquids cannot enter the pore network below its liquid-entry pressure while gases pass freely. Each square sheet is engineered for one job - moving gas at a predictable rate while keeping water, mist and contamination absolutely out.

Products Specifications

Material	PTFE
Filtration grade/Pore size	5 um
Size	1001000.2mm
Porosity	≥ 80%
Service temperature	−200 °C to +260 °C continuous
Chemical compatibility	Stable across pH 0–14; resists strong acids, alkalis, solvents, oxidizers, and corrosive gases

Products Features

Precision 5 μm Pore Size - the Sweet Spot Between Flux and Leak-Tightness

Pore size governs everything. At an average 5 μm with a narrow distribution, the plate achieves airflow of 0.10–0.15 L/(min·cm²) at 7 kPa while still holding a 20 kPa-class water entry pressure. Gas flows freely; liquids stay locked out. This balance has been validated across electrochemical sensors and packaging vents, sparing engineers the trial-and-error between breathability and leak-proofing.

0.2 mm Self-Supporting Thinness - Short Path, Fast Response

No backing layer is required. The 0.2 mm diffusion path is an order of magnitude shorter than conventional 2–4 mm sintered metal or ceramic barriers, so concentration changes reach the sensing element sooner: faster t₉₀ response, lower dead volume and a lower assembly profile for compact instrument designs.

Intrinsic Hydrophobicity - All-Weather Gas/Liquid Separation

Hydrophobicity comes from the PTFE molecule itself, not a surface coating, so it cannot wear off or wash out. With a contact angle above 120°, the membrane keeps its dry-state strength and airflow even after months at 100% relative humidity or repeated condensation cycles - eliminating the airflow collapse common to coated media.

Extreme Environment Tolerance - −200 to +260 °C, pH 0–14

A C–F bond energy of 485–532 kJ/mol gives the sheet near-ultimate resistance: strong acids, strong alkalis, organic solvents, aggressive oxidizers and corrosive gases such as ozone, SO₂ and NOₓ leave it untouched. Dimensional and functional stability from cryogenic temperatures to 260 °C suits outdoor, downhole, flue-gas and chemical-plant service.

High Porosity with Narrow Pore Distribution - Uniform, Batch-to-Batch Consistent

Biaxial stretching distributes more than 80% porosity evenly through the sheet, giving low airflow variation across the full area and minimal anisotropy. For sensor makers this translates into calibration curves that repeat from lot to lot; for vent valves, an exhaust rate that stays predictable on every single cap.

Clean and Easy to Process - Die-Cut, Heat-Seal, Laminate

The pure PTFE composition is lint-free, low-extractable and ionically clean, meeting high-purity and cleanroom requirements. The 100 × 100 mm square nests at near-100% utilization, die-cuts into any outline, heat- or ultrasonic-seals at the edge, and laminates to PET, nonwovens or carbon paper for composite builds.

applications

Application 01 · Electrochemical Gas Sensors

Diffusion Barrier & Protective Membrane
Limiting-current electrochemical sensors depend on gas reaching the working electrode at a controlled rate. The 5 μm / 0.2 mm combination provides a precisely locked diffusion resistance, so the output current tracks gas concentration alone and stays decoupled from wind and sampling-flow fluctuations. At the same time the hydrophobic membrane seals electrolyte inside the cell - no drying out, no weeping - while blocking dust, droplets and corrosive media. Ideal for portable and fixed CO, NO₂, SO₂, O₂ and H₂S detectors.

Application 02 ·

Hydrogen Fuel Cells & Metal-Air Batteries

Gas Diffusion Layer / Waterproof Breathing Layer
Fuel cells and zinc-air batteries demand continuous oxygen ingress with zero electrolyte leakage - the classic arena for gas-permeable, liquid-tight materials. As a cathode-side diffusion layer or waterproof breathing film, the plate keeps its pores open under stack compression to feed the catalyst layer continuously, while its hydrophobic character suppresses flooding and the voltage dips caused by water-blocked channels. Laminated onto carbon paper it also serves as the hydrophobic functional layer of composite GDLs.

Application 03 ·

Medical Devices & Pharmaceutical Processing

Sterile Venting Components
IV-bag and administration-set vents, breathing-circuit and nebulizer inlets, and sterile vents on culture flasks and fermenters must exchange gas while stopping bacteria, mycoplasma and aerosolized droplets. Because the membrane is hydrophobic, condensate never bridges the pores; the 5 μm structure delivers high retention of bacteria-laden aerosols. The material is biologically inert and withstands ethylene oxide and gamma sterilization, fitting both long-term device and IVD requirements.

Application 04 ·

Chemical & Reagent Packaging

Packaging Vent Valves and Cap Liners
Hydrogen peroxide, sodium hypochlorite and fluorinated cleaning agents keep generating gas in storage and transit, swelling sealed containers until they bulge or burst. Die-cut into discs under caps and drum lids, this plate turns packaging into a controlled breather: accumulated gas escapes steadily while liquid stays sealed through tilting, rain and vibration. PTFE's tolerance of strong oxidizers far exceeds polyolefin vent media, making it the preferred liner for hazardous-chemical transport packaging.

Application 05 ·

Aeration, Degassing & Gas-Liquid Mass Transfer

Fine-Bubble Diffusers and Membrane Degassing
In wastewater treatment and aquaculture aeration, the plate works as the diffusion medium of fine-bubble aerators: 5 μm pores shear air into dense microbubbles that multiply the gas-liquid contact area, raising oxygen-transfer efficiency and cutting blower energy. The non-stick hydrophobic surface resists biofouling and oil, recovering fully after backflush. Used in reverse as the heart of vacuum degassing modules and membrane contactors, it strips dissolved O₂ and CO₂ from boiler feedwater, ultrapure water and fermentation broths.

Application 06 ·

Precision Instruments, Electronics & Semiconductor

Sampling Protection and Gas-Cell Windows
IR/UV gas-analyzer inlets, VOC and ambient-air sampling probes, equilibration vents on semiconductor process chambers and gas cabinets, and pressure-equalization valves on outdoor cabinets and vehicle controllers - every precision interface that must breathe with its environment yet tolerate no dust or condensate benefits from this plate. It equalizes intake, blocks particles and droplets from optics and sensor windows, and its intrinsic inertness withstands corrosive process gases in cleanroom and field conditions alike.

FAQ

FAQ

Why is a 5 μm pore size ideal for gas diffusion applications?

Five microns sits in the mixed Knudsen–molecular diffusion regime: flux stays close to free molecular diffusion, yet the diffusion resistance is fixed by the membrane geometry. That yields high airflow with a stable, reproducible resistance - exactly what limiting-current sensors and metered venting require - while still maintaining a meaningful hydrophobic water entry pressure.

Is the plate waterproof? What happens in heavy rain or 100% humidity?

Yes. As an intrinsically hydrophobic PTFE membrane it resists liquid water entry up to typically 20 kPa (tunable higher with a smaller pore size), and its wet strength equals its dry strength. Airflow does not collapse in saturated air, repeated condensation or direct water spray.

Can the sheet be customized or laminated into my assembly?

The 100 × 100 mm square die-cuts into any shape with near-zero waste and laminates to PET, nonwovens, adhesives or carbon paper. Pore size (0.1–10 μm), thickness, width and roll format are all customizable - share your target airflow, water entry pressure and part drawing for a tailored recommendation.

What chemicals and temperatures can it handle?

The plate is stable across the full pH 0–14 range and resists strong acids, alkalis, organic solvents and oxidizers. Continuous service spans −200 °C to +260 °C, covering cryogenic, autoclave-adjacent, flue-gas and chemical-plant environments.