Working Pressure	2-4[bar]	29-58[psig]
Working Air Volume	19-100[m³/min]	671-3531[cfm]
Working Power	75-315[kw]	101-422[hp]

Advantages and Features:

• Can save over 30% electricity;
• The low-pressure air end can automatically adjust the internal compression ratio according to the operating pressure, maintaining optimal energy efficiency within the 2-5bar exhaust pressure range;
• In many industries such as chemical, glass, petroleum, textile, printing and dyeing, and ceramics, the working pressure required for compressed air is only 3-5bar. However, currently, these industries usually use air compressors of 7-10bar connected with pressure reducing valves to achieve low pressure; this is undoubtedly a considerable waste of energy. To address this, UNITED OSD developed low-pressure screw air compressors, directly outputting the low-pressure compressed air required by these industries; the compressors consume less energy, meet production requirements, and significantly improve users' production costs.

Mechanical System

Independently developed dedicated main unit

• Internationally leading molded lining, 4:6 gear ratio, fewer teeth and more air intake;
• Large rotor, low speed, long lifespan;
• The internal oil circuit of the main unit can precisely control the oil injection volume, aiding lubrication and cooling to achieve optimal performance;
• SKF bearings adaptable to load changes, flexible, time-tested, durable, ensuring the lifespan of the main unit.

Low-Pressure Screw Air End Drive Chain

• The drive motor directly connects to the two-stage compression main unit without a coupling, resulting in a maintenance-free drive chain and a 1% reduction in energy consumption;
• The IP55 fully enclosed motor and main unit casing are integrated, effectively preventing pollutants such as metal particles, dust, and moisture from penetrating the motor and main unit, making the compressor performance more stable;
• The motor bearings adopt reinforced cylindrical + ball bearings, offering higher strength and reliability;
• Transmission gear machining precision up to aerospace grade 6, multiple heat treatments and related processing technologies ensure all mechanical parts have superior surface hardness, ultra-high wear resistance, and yield strength;
• Independent oil supply system and precise oil filtration effectively ensure the stability and reliability of the entire gearbox under long-term full-load operation.

Intake and Filtration System

Pre-filter protection layer:

Prevents large dust particles, cotton, and other debris from entering the air compressor. Keeps the inside of the compressor clean. Strictly monitors the first pass of compressed air.

Particulate Air (HEPA) Filtration:

Heavy-duty air filtration system supported by Donaldson, with a filtration accuracy of up to 99.9% for particles larger than 3μm. Suitable for various heavy dust environments.

Dual Large-Diameter Air Intake Assembly Design:

The pressure difference of all air paths is less than 0.2bar, significantly extending the service life of the air filtration system.

Optimized Design of Large-Diameter Intake Valve:

Low energy consumption during no-load operation, cast aluminum material, more stable performance.

Optimized Mold Design for Intake Pipe:

High-strength rubber seal, firm and durable.

Oil Filter:

Donaldson oil filter, high clean filtration level, effectively protects the main unit bearings for safe operation and extends the main unit's service life.

Oil-Gas Separation System:

European-designed oil-gas separation core; fiberglass filter material; long lifespan; less frequent replacement needed. The collection separation core works synergistically with the oil return device to effectively recover and circulate lubricating oil, preventing oil overflow and ensuring the compressed air exhaust oil content is ≤2ppm.

Lubricating Oil:

UNITED OSD lubricating oil possesses many characteristics such as good oxidation resistance, high-temperature resistance, high flash point, and excellent thermal conductivity.

Cooling System

• The heat exchange design margin is 20%-50%, ensuring stable operation of the compressor in extreme environments and minimizing pressure drop.
• Standard motor frequency conversion, accurate oil temperature control; further reducing air compressor energy consumption.

Features of Permanent Magnet Synchronous Motor (PMSM)

• Motor efficiency up to 96%, power factor 0.98, far exceeding Level 1 energy efficiency standard;
• High coercivity, high-temperature resistant permanent magnets ensure no demagnetization at 180℃ high temperature;
• Independent fan cooling ensures safe operation of the motor for long durations and at low frequencies;
• Class F insulation, 70K temperature rise design, suitable for high-temperature conditions of air compressors;
• Fully enclosed IP55 protection, protecting the motor's internal environment cleanliness, extending the lifespan of permanent magnets and insulation;
• Built-in temperature protection, protecting winding insulation and permanent magnets.

Permanent Magnet Synchronous Motor vs. Ordinary Asynchronous Motor

Efficiency:

Eliminates excitation system losses and improves efficiency.

Maintained under low load conditions:

PMSM's energy efficiency is more than 9% higher than asynchronous motors, and it remains unchanged as frequency decreases.

High Starting Torque:

The maximum starting torque of permanent magnet synchronous motors can reach up to 3 times the rated torque, while general asynchronous motors only reach 1.6 times.

More stable control:

PMSM response time is less than 50ms. Air output can be instantly adjusted within a wide range to precisely stabilize air pressure.

Features of UNITED OSD VFD Variable Speed PMSM Air Compressor

• Ultra-low temperature rise design ensures long-term stable operation of the compressor at low frequency;
• Adopts open-loop vector control system for faster control speed and more accurate speed regulation;
• The compressor unit can still operate when the frequency drops by more than 50%;
• Stable pressure, pressure fluctuation precisely controlled within 0.01mpa; features soft start, avoiding starting current impact and reducing starting energy consumption.

Electrical System

New Generation Smart Controller	IoT Module	High-quality Electrical Components
PLC + touch screen;  User-friendly interface;  Full-process monitoring of operating status;  Smart operation;  USB, COM interface, with upgradeable function.	Remote monitoring and operation & maintenance;  Remote operation,  Data acquisition,  Energy-saving management.	Siemens electronic components;  Variety of choices;  Suitable for all climate conditions.

The UNITED low-pressure series screw air compressor is a new type of compressor developed for energy saving, emission reduction, and environmental protection needs. It changes the traditional high-pressure compressor's method of reducing compressed air pressure before supplying it to air equipment, thereby saving energy. Currently, in the screw air compressor industry, UNITED's exhaust pressure can be as low as 1.2bar, ensuring that the exhaust oil content is less than 2ppm, providing clean and stable air supply. Its enclosed cabinet and low-noise design are more environmentally friendly than piston compressors. Given that many industries do not require downtime, continuous operation maintenance can be guaranteed; equipped with a fault alarm, it prepares users for emergencies, ensuring stable and reliable operation.