Sierra SM/SL/SH90/110 Ingersoll Rand Oil-free Screw Air Compressor
• Product Overview
The Ingersoll Rand Sierra® Series two-stage compression zero-oil screw air compressor features a time-tested design incorporating multiple industry-leading technologies. Paired with a robust two-stage compression module, UltraCoat™ coating technology, a unique triple-seal design, 46°C ambient temperature capability, reliable bearing components, and an intelligent control system, it delivers an efficient zero-oil compressed air solution.
• Product Features
Rugged and durable two-stage compression module
Ingersoll Rand compressor hosts are renowned worldwide for zero failures and minimal maintenance costs. Sierra® units feature a two-stage compression host, where twin-screw compression reduces thermal load on each stage. The second-stage rotors are constructed from stainless steel to resist moisture corrosion. The rotor surfaces are mechanically sprayed with Ingersoll Rand's patented UltraCoat™ super coating, ensuring excellent sealing between rotors and guaranteeing sustained air volume without degradation over time.
• Unique UltraCoat™ Super Coating
Ingersoll Rand's unique UltraCoat™ super coating utilizes a molybdenum disulfide matrix compound, offering high hardness and exceptional adhesion while providing outstanding oxidation resistance. The rotor coating is applied via robotic spraying, ensuring uniform coverage across the rotor surface. Prior to coating, the screw rotor undergoes specialized shot peening to enhance surface roughness, facilitating superior coating adhesion.
The exceptional performance of the UltraCoat™ coating enables users to achieve sustained air delivery without volume decay over extended compressor operation. Most manufacturers use softer Teflon coatings applied non-uniformly without robotic spraying. During continuous operation, these coatings gradually peel off due to thermal expansion/contraction and moisture corrosion, leading to increased rotor clearance and reduced airtightness. This typically causes an 8%-10% air volume decay, increasing overall unit operating costs.
• Superior sealing design ensures oil-free compressed air chambers.
The unit employs a unique triple-seal design, completely isolating the lubricated bearing oil circuit from the air circuit to guarantee oil-free compressed air.
SS Air Seal – Prevents air ingress into oil circuits (bearing housings / gears)
Labyrinth Seal – Prevents oil ingress into the main AIR END
Oil Drain Seal – If leakage occurs in the above seals, the oil drain seal vents oil to the atmosphere
• High Ambient Temperature Design
The units are engineered for subtropical environments with high temperatures and humidity, with a maximum design ambient temperature of 46°C, thereby preventing shutdowns caused by summer heat. All Sierra® water-cooled and air-cooled units operate reliably in harsh conditions.
• High-Reliability Components
Bearings
Each Sierra® host stage features roller bearings at the inlet end to support radial loads on the screw rotors via line contact. Additionally, angular contact ball bearings are installed at the outlet end to withstand axial thrust. Oil-free screw compressor rotors require extremely tight clearances to ensure top-tier efficiency. Angular contact ball bearings precisely maintain the rotors in a specially engineered position. This bearing design significantly reduces compressor failure rates and extends overhaul intervals.
• Air Intake System
The Sierra® air intake valve is hydraulically controlled for high reliability, differing from some manufacturers' rubber diaphragm valve drives that require frequent maintenance and replacement.
A combined intake and exhaust valve controls loading/unloading. During loading, the butterfly valve fully opens while the bleed valve closes simultaneously. During unloading, the butterfly valve closes, allowing air to circulate through a small orifice in the valve disc and simultaneously actuating the bleed valve to vent.
Oil vapors discharged from the breather cap of oil-free screw compressor tanks are expelled directly with hot air outside the housing. This ensures the host unit inhales absolutely oil-free air.
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