China 20 Hp Rotary Screw Air Compressor Manufacturer & Exporter

Free Air Delivery (FAD) varies primarily as a function of the working discharge pressure. On our single-stage 20 HP Permanent Magnet VFD platform, expected delivery ranges from approximately 2.35 m³/min (83.0 CFM) at 8 bar (116 PSI), down to 2.10 m³/min (74.1 CFM) at 10 bar (145 PSI), and 1.85 m³/min (65.3 CFM) at 13 bar (188 PSI). On our high-efficiency two-stage models, airflow expands to 2.62 m³/min (92.5 CFM) at 8 bar due to inter-stage cooling and reduced volumetric blowback across the rotor lobes.

Traditional fixed-speed compressors operate via an inefficient "load/unload" cycle. When downstream factory demand drops below capacity, an inlet throttle valve shuts, forcing the motor to idle while still consuming 40% to 50% of its rated electrical wattage just to churn internal vacuum oil without generating usable compressed air. A Permanent Magnet VFD compressor continuously measures target line pressure via sensitive pressure transducers and dynamically accelerates or decelerates the motor RPM to match demand exactly. It consumes only the electrical energy required to produce the precise volume of air consumed, maintaining line pressure within a narrow ±0.1 bar band.

For a standard 380V / 50Hz 3-phase supply, a 15 kW motor has a nominal Full Load Amperage (FLA) of approximately 29.5 Amperes. Factoring in cooling fan motors, power inverter efficiency factors, and a 1.25 National Electrical Code (NEC) safety margin, a 40A to 50A motor-rated circuit breaker (Class C or D curve) with appropriately rated 10 mm² copper conductor cabling is specified. Because PM VFD platforms ramp up smoothly via soft-start inverter curves, instantaneous inrush currents are eliminated entirely (starting current is ≤ 1.0× rated current), safeguarding local transformer substations from brownout dips.

As an engineering rule of thumb, buffer storage receiver capacity should equal roughly 20% to 30% of total rated FAD per minute. For a 20 HP compressor generating approximately 2.3 m³/min, an air storage vessel with a capacity of 500 Liters to 1,000 Liters (130 to 260 Gallons) is optimal. In applications with sudden cyclic demand surges (such as rapid pneumatic stamping presses or sandblasting cabinets), an oversized 1,000-liter tank provides critical thermal cooling mass, reduces moisture condensation loading on the downstream refrigerated air dryer, and prevents artificial high-frequency cycling of the compressor motor drive.

Upgrade to 100% oil-free when air contacts products directly in food processing, beverage bottling, pharmaceutical synthesis, printed circuit board manufacturing, or precision optical coating. While oil-injected compressors utilize coalescing filters to suppress oil down to 1–2 PPM, filter saturation, maintenance lapses, or high ambient temperatures can lead to catastrophic oil blow-by. A water-lubricated oil-free compressor utilizes purified water as the internal fluid medium—delivering ISO 8573-1 Class 0 verified purity, eliminating expensive carbon-adsorber maintenance, and removing liability for contaminated inventory.

Yes. Unlike reciprocating piston compressors which require intermittent duty cooling cycles (typically rated for 50–70% duty cycles to avoid valve carbonization), rotary screw compressors are engineered specifically for continuous 100% full-load duty cycles (24/7/365). Continuous operation is thermodynamically advantageous for screw units, keeping system oil at a steady operating equilibrium (between 78°C and 88°C) to vaporize ambient moisture within the separator tank, preventing internal emulsion sludge formation and premature component corrosion.