VFW Series Medium Pressure Oil-Free Piston Air Compressors

PET bottle blowing, high-pressure purging and some chemical and precision processes place two requirements on compressed air at the same time: the pressure must be high enough and the air must be clean enough. The first is determined by the model and the number of compression stages; the second by whether the air touches lubricating oil during compression. Many users weigh these two points back and forth and end up having to accept the extra cost and risk that compressed air treatment equipment brings.

The Fusheng VFW Series medium-pressure oil-free piston compressor is designed to resolve this conflict. Used mainly in industrial bottle blowing and similar fields, it covers a compressed air outlet pressure of 2.5-4.0MPa, air delivery of 3.6-23m³/min and power of 37-220kW, and the entire compression process is completely oil-free, guaranteeing compressed air quality at the source.

Why Bottle Blowing Needs Oil-Free Throughout

The air used in bottle blowing comes into direct contact with the preform. If the air supply contains oil, oil mist may cling to the bottle surface, affecting forming quality and creating problems with later cleaning and compliance. There are two common ways to deal with this: an oil-injected machine plus multi-stage filtration to remove oil, or an oil-free machine outright. The first relies on filter elements, which saturate and need replacing, and there is a risk once they fail; the second never touches lubricating oil from the compression chamber onward, so the output air is oil-free at the source. The VFW is the second kind.

Large Bore, Low Speed, Long Stroke: Building Reliability and Life into the Structure

The reliability of an oil-free piston machine depends largely on the loads and wear on its moving parts. The VFW uses an efficient, reliable design with a large bore, low speed and long stroke: a large bore means speed can be lower for the same air delivery, and a long stroke makes each reciprocating stroke do its work more completely. Low speed brings less vibration, lower noise and slower wear, while the long stroke helps raise volumetric efficiency. Together these choices deliver stable performance under long, continuous running.

Multi-Stage Compression and Reinforced Cooling

To reach 4.0MPa under oil-free conditions, multi-stage compression is almost inevitable. Once stages are added, the quality of intercooling directly determines the efficiency and life of the machine: good intercooling means a lower inlet temperature for the next stage, less compression work and a smaller heat load on components. The VFW reinforces its cooling system to control the discharge temperature of each stage, bringing the compression process as close to ideal as possible and thus balancing air output with the oil-free requirement.

It is worth noting that the oil-free structure also changes what routine maintenance involves. There is no longer any need to track oil quality and oil-change intervals; upkeep centres more on the intake filter, piston rings and valves. For users who treat the equipment as a production tool and want maintenance to be simple and clearly defined, that change is a value in itself.

Technical Specifications at a Glance

The data sheet shows the VFW series running from VFW-50/4 through to VFW-300/4, with air delivery increasing by model. Because it is an oil-free piston design, at the same pressure level a larger air delivery corresponds to a larger bore configuration, so selection should take the installation space and foundation load capacity into account together.

Industries and Applications

• PET bottle blowing and blow moulding: the air comes into direct contact with the preform, so oil-free is a basic requirement;
• Food and beverage packaging: compressed air may come into contact with packaging or product;
• Pharmaceuticals and fine chemicals: production steps sensitive to air cleanliness;
• High-pressure purging and pneumatic control: where higher pressure is needed without introducing oil contamination.

Selection Advice

1. Confirm cleanliness requirements first: an oil-free machine solves the oil content of the air supply itself, but dew point and dust content still need drying and filtration configured separately to process requirements;
2. Take pressure as actually required: the VFW covers 2.5-4.0MPa, and selection should match the true process pressure, avoiding unnecessary investment in high pressure;
3. Size the model by peak air demand: processes such as bottle blowing concentrate their air use, so model size should follow the peak requirement;
4. Assess long-term maintenance cost: the oil-free structure reduces consumption of oil and oil-removal filter elements, but wear parts such as piston rings and valves still need periodic servicing.

Final Thoughts

In processes that need both high pressure and clean air, oil-free is not a bonus but the price of entry. With its large-bore, low-speed, long-stroke structure and reinforced intercooling, the Fusheng VFW Series delivers complete oil-freedom and stable air output at the same time. For users of bottle blowing and high-pressure clean air, it is a technical route worth comparing seriously.