The unit is installed at the storage tank breather valve. It starts automatically during unloading or when tank pressure exceeds the preset value. Process flow:
① Compression — a compressor pressurizes and liquefies the vapors; ② Condensation — an air-cooled heat exchanger cools the mixture; ③ Separation — a gas-liquid separator collects the liquid, which flows back into the tank; ④ Membrane separation — the remaining gas enters the membrane module: fuel molecules adhere to the membrane surface and, driven by the vacuum pump's negative pressure, pass through the membrane to the central tube and return to the tank, while air does not pass through and is vented directly.

When tank pressure drops below the preset stop point (<50 Pa), the unit automatically goes to standby; it restarts automatically when pressure rises again — fully unattended.

Handling capacity 4–20 m³/h, covering daily station breathing losses up to larger sites. The unit starts and stops automatically based on tank pressure — it adapts to rush hours and overnight low demand with no manual operation.

Recovery rate above 99%, NMHC (non-methane hydrocarbon) treatment efficiency above 99%, and emission concentration far below national limits. Benzene, toluene and xylene removal also outperforms regulatory requirements, with actual emissions well under integrated emission limits. Membrane separation is a purely physical process — no solid waste, no liquid waste, no secondary pollution.

Both models handle 4–20 m³/h and share the same footprint (1300×900×1160 mm). They differ in power and noise:

• Combined-pump (single membrane): 1.3 kW, noise ≤63 dB, 390 kg — vapors pass the membrane first and return via vacuum pump; no compression-condensation stage, lower power and quieter.
• Air-cooled + membrane: 2.7 kW, noise ≤75 dB, 410 kg — includes air-cooled compression-condensation, suited to higher vapor concentrations and larger recovery volumes.

Choose the combined-pump version for energy- or noise-sensitive sites; choose the air-cooled version for higher throughput. Or send us your site details and we will recommend the right model.

No — this is a key Vohon advantage: gravity self-flow return design. The return piping is 500–550 mm above ground, so recovered liquid flows back into the tank by gravity — no return pump, no raised platform.

Many competitors place the return line at the unit bottom (only 30–50 mm off the ground), so the liquid cannot flow back unless the owner raises the platform 500–550 mm — that means civil works. Vohon units connect directly to existing piping: less site work, faster install, fewer failures.

The unit is fully skid-mounted and factory-tested. On site it is simply connected to the vapor piping and electrical supply — typically 1 day to install, with little impact on daily station operation. Piping uses clamp-type connections, and power/signal cables are connected without opening the explosion-proof box.

Membrane design life is 10 years or more — practically no consumable replacement under normal use, no carbon-bed change-outs and no hazardous waste disposal. Vohon produces its own membrane materials (annual capacity 1.2 million m²+, 30,000 membrane modules per year), so spare cost and supply are both guaranteed.

Combined-pump version 1.3 kW, air-cooled version 2.7 kW. The unit starts and stops with tank pressure, so actual running time is short — unit energy use ≤0.2 kWh/m³, very low electricity cost. Noise: ≤63 dB (combined-pump) / ≤75 dB (air-cooled) — the combined-pump version is close to indoor office levels and quiet enough for night operation.

The whole unit is built to explosion-proof requirements: explosion-proof electrical box and components, enclosure rating IP55, operating ambient temperature -40 ℃ to 70 ℃ — normal operation even in northern winters. Automatic tank-pressure control keeps the underground tank at atmospheric pressure; the unit comes with an exhaust pipe, flame-arresting cap and emission sampling port.

Yes. The unit features a 12.1-inch touchscreen industrial PC showing real-time tank pressure, running time, alarms, emission concentration and throughput; it supports RS485 and WiFi / 4G connection with data uploaded to the cloud — view and manage multiple stations from a phone APP or web portal.

Data can be transmitted directly to the oil company or environmental monitoring platform over the intranet, tamper-proof and leak-proof; custom protocols for station online monitoring systems are available on request.

Quick comparison of the four mainstream technologies:

• Condensation: high power use, slow displacement, wastewater, average stability and higher maintenance.
• Adsorption: needs desorption and dilution, long time and high temperature, periodic carbon replacement, some vapor breakthrough.
• Absorption: absorbent selectivity is limited and affected by local air composition and seasonal temperature.
• Membrane separation: effectively separates fuel vapor from air — long service life, low failure rate, high stability, currently the best treatment performance.

Membrane separation produces no solid or liquid waste and needs no consumables — lower total running cost.

Recovered fuel is water-free — no secondary dewatering needed; sulfur and gum content meet requirements and no impurities are added, so it can be returned to the tank and resold. Recovered vapor becomes quality liquid fuel — real revenue counted by the tonne.

Both models are running at real stations:

• Beijing gas station: pure membrane unit (combined-pump single-membrane version)
• Chengdu gas station: air-cooled + membrane unit

Vohon supplies Sinopec and PetroChina provincial subsidiaries on a long-term basis — hundreds of units delivered in recent years, including batch orders and framework agreements, with customers across 20+ provinces. The same membrane technology also serves chemical and pharmaceutical VOCs treatment.

Warranty: whole unit 12 months (or 18 months after delivery), membrane module 24 months (or 30 months after delivery); free installation guidance and commissioning, 4-hour response, 24-hour on-site service, lifetime technical support; warehouses in most provinces for fast spare parts.

Ordering process: ① send your station size, tank volume and pressure data → ② free model recommendation and quotation → ③ technical agreement confirms parameters → ④ production with full factory test → ⑤ on-site installation, commissioning and acceptance → ⑥ regular follow-up during warranty.