SWV Series PM VSD Screw Air Compressors

In industries such as food, pharmaceuticals, electronics and precision coating, compressed air sometimes comes into direct or indirect contact with the product. In such cases even a trace of oil mist in the air supply can become a quality risk. To obtain oil-free compressed air, the common approach is to add multi-stage filtration after an oil-injected machine, but filter elements gradually saturate with use and need regular replacement, leaving a lingering worry about failure.

The Fusheng SWV series water-lubricated oil-free screw air compressor takes a different route: RO-purified water replaces lubricating oil to handle lubrication and sealing, achieving completely oil-free operation from the compression stage itself. The series has a working pressure of 0.7–0.9MPa, air delivery of 2.0–20m³/min and power coverage of 15–120kW, driven by PM VSD.

Water Instead of Oil: Another Route to Oil-Free Compression

An oil-injected screw machine needs lubricating oil because oil simultaneously serves lubrication, sealing and cooling. SWV's thinking is this: since the roles of oil can be separated out, RO-purified water can handle lubrication and sealing just as well, keeping the necessary sealing between the rotors, and water itself brings no oil contamination.

As a result there is no lubricating oil at all in the compression chamber, and the compressed air delivered is oil-free at the source, without relying on downstream filter elements as a fallback. The load on the downstream filtration system, and the running cost of replacing filter elements, are both noticeably reduced.

Twin Screws and a Special Coating: Durability Built into the Design

Water-lubricated models demand more of the rotor surface treatment. SWV uses a twin-screw design, with rotors treated with a special coating for super-durable properties and minimal wear over long operation, sustaining high compression efficiency. At the same time, the water-lubricated structure means fewer routine maintenance items and lower maintenance costs — a tangible cost advantage for users who want long, stable operation.

PM VSD: Beyond Cleanliness, Saving Power

Oil-free is a requirement of air-supply quality; saving power is a requirement of running cost; the two do not conflict. The SWV series uses PM VSD, with motor speed adjusted continuously to air demand: as demand falls, speed drops in step, avoiding the energy wasted when a fixed-speed machine blows off at no load during load/unload cycling, and keeping network pressure steadier.

According to the specification table, the series is listed as air-cooled, meaning the units depend less on an external circulating-water system and are relatively simple to install and lay out. For the full configuration of a specific model, refer to the specification charts lower on the page.

Three Things to Settle Before Choosing a Water-Lubricated Model

The advantages of water-lubricated oil-free models are clear, but a few points need confirming in advance when selecting:

• Water quality: the unit uses RO-purified water as its lubricating and sealing medium, so water cleanliness directly affects running condition; whether a stable supply of purified water exists on site needs to be established in advance;
• Ambient temperature: oil-free models are relatively sensitive to intake air cleanliness and ambient operating temperature, so room ventilation and filtration should be considered together;
• Compressed air treatment: oil-free only solves the oil content question; if the process has separate requirements for dew point or dust content, corresponding drying and filtration equipment is still needed.

Confirm these three points, then use the specification table to choose pressure and air delivery, and the selection will usually be far more solid.

Specifications at a Glance

Note that for the same model air delivery differs from one pressure point to another. Take the models in the table: raising pressure from 0.7MPa to 0.9MPa lowers air delivery accordingly. When selecting, fix the most commonly used working pressure first, then match air delivery at that pressure.

Industries and Applications

• Food and beverage: compressed air often contacts materials and packaging, so oil-free is a basic threshold;
• Pharmaceuticals and medical devices: clean air is a necessary condition for compliant production;
• Electronics and semiconductors: even trace oil contamination can affect product yield;
• Precision coating and pneumatic control: oil contamination affects coating adhesion and valve service life;
• Textiles and chemical fibres: process steps with high demands on air-supply cleanliness.

Selection Advice

1. Confirm the cleanliness class first: requirements for oil content, dew point and dust content vary widely by process; use them to decide whether drying and filtration are still needed after an oil-free machine;
2. Take pressure from actual demand: among the three points 0.7, 0.8 and 0.9MPa, choose the one closest to the point of use; the higher the pressure, the smaller the available air delivery usually is;
3. The return on VSD is proportional to demand fluctuation: the less regular the demand, the more obvious the energy savings from VSD control;
4. Count the whole-life cost: the value of an oil-free machine lies not only in clean air but also in fewer filter replacements and lower downtime risk.

Conclusion

For most industries, compressed air only needs to be good enough; but in cleanliness-sensitive industries, oil-free is the bottom line, not a bonus. The SWV series builds that bottom line into the product design through water lubrication, while twin screws and a special coating pull durability and efficiency back up, and PM VSD adds running economy on top. Clean, low-hassle and power-saving at once, it earns a place on the shortlist.