This article endeavors to discuss the details, benefits, operation and features of the Rotary Screw Compressor. With a view that this information may assist a customer in understanding the machine and provide guidance in the early stages of decision-making before purchase.

First, What is a Rotary Screw Compressor?

The Rotary Screw Compressor is a powerful air compressor that provides large quantities of dry, clean, continuous pressurized air to power tools, equipment, and industrial settings. The rotary compressor is a reliable, hard-wearing air compressor and a more efficient, newer, improved compressor-style than the Reciprocating Compressor. Its key concepts are no metal-to-metal contact; variable speed drives to match the compressor's demand and performance, resulting in reduced power consumption and, finally, a simplified installment process.

The Rotary Screw Compressor may be the more expensive compressor style when compared to piston compressors, but its features have quickly made it a popular purchase for commercial and industrial applications globally. The rotary screw air compressors are used in varied industrial applications. Rotary screw compressor brands like Atlas Copco & Rotair are well known for their high-end designs, advanced features and technologies that offer cost-effective, long-lasting, reliable & premium compressed air solutions suitable for light to heavy-duty applications across the industry.

So, How Does a Rotary Screw Compressor Work?

The central principle to a Rotary Screw Compressor is the male (helical lobes) and female (helical grooves) rotors spinning opposite directions. The rotary screw uses these two rotors to push air through the compressor, which creates pressure. Compression is accomplished through the rotors meshing within the housed section. Simultaneously, the air inlet port sits at the top of the housed section (towards the drive shaft end of the machine) to draw in air, and the discharge port sits at the opposite bottom end to release the final pressurized air.

In the oil or water injected designs, fluid is introduced to remove the heat of compression, seal internal clearances, and prevent rotor-to-rotor contact. In oil-free designs, timing gears are attached to the rotor shafts to prevent rotor-to-rotor contact. These multiple stages improve the efficiency of the compressor and enable it to achieve higher pressures.

Although they belong to the same class, rotary screw compressors are more complex than piston compressors. As such, the speed of the screw rotors optimizes at a certain level, minimizing the mechanical losses (due to heat at very high speed) and volumetric losses (air losses due to very low speed) during compression.

Oil-Lubricated and Oil-Free Rotary Screw Compressors Explained

The technical name is oil-lubricated but is also known by such variants as oil-flooded or oil-injected compressors. These oil-lubricated models work by injecting oil into the compression chamber to cool and lubricate the compressor element, remove the heat from the compression process, and minimize leakage in the compression chamber. A vital feature of the oil-lubricated models is the absence of the duty cycle, meaning that the oil-lubricated rotary screw compressor can run continuously with no ill effects.

Due to their continuous running, the oil-lubricated models avoid costly downtime and production delays even under extremely harsh conditions. They are well known for these high-performance traits and have been engineered expertly to ensure a trouble-free long life with low operating costs. In addition to low-noise operation, compact size, and integrated air treatment equipment, the integrated options save energy by reducing pressure variations.

The second kind of compressor for discussion is the oil-free screw compressor. Akin to the oil-lubricated variant, oil-free screw compressors have other names, such as oil-less compressors or no oil compressors. These names can be somewhat misleading though, these models are void of oil as a lubricant in the compression process but use oil as a lubricant for motor cooling or removing heat from the rotors.

The oil-free compressors sometimes use water as an alternative lubricant or rely on a special coating applied to the rotor elements, eliminating the need for a lubricant at all. These compressors are generally purchased for use in the food and beverage or pharmaceutical industries as they are better suited for stringent operational regulations.

Key Benefits of Choosing a Rotary Screw Compressor

The Rotary Screw Compressor offer a range of key advantages as a compressor; the features typically commented on regarding this model are outlined below.

Rotary Screw Compressor Benefits:

• Very high energy efficiency
• Engineered for continuous operation, with minimal downtown
• Pulsation-free air flow
• Functional in varying weather conditions, from very high temps to very low temps
• Low noise output - described as being no louder than a dishwasher
• Generates low levels of heat when compared with other types of compressor
• Built to ensure the lubricating oil remains sealed inside the equipment, this means the area around the compressor stays dry, clean and suitable for use in spaces requiring low air moisture.
• Zero to low loss of capacity over time
• Low oil-carryover (as little as three ppm) in oil-lubricated machines
• Variable speed drives
• Can be monitored remotely
• Whether water-cooled, air-cooled or oil-filled, the often-intense heat generated by the process of air compression is managed and dissipated within the compression chamber itself ensuring that internal components are never exposed to extreme operating temperatures
• Maintenance is simple in screw-based air compressors, this equals low maintenance costs and scheduling, which is helped along by the machine containing fewer parts and well-built components

Rotary Screw Compressors: understanding capacity and pressure and the role they play

A combination that guides most purchases when buying a rotary screw compressor is the combination of supply and pressure. Knowing how much-compressed air you will need and the pressure required for the tools/industry for application is an essential first step to figure out.

Some steps can guide to finding out this information, to use a base in formulating the correct pressure and capacity for your needs:

• To determine the pressure and capacity for your needs, check the manuals or spec sheets of your pneumatic equipment; this will indicate the operating pressure of the equipment and the amount of air required.

• An important note to make is the part that requires the highest pressure dictates the required pressure. Then, as a rule of thumb, add 1.5 bar to the minimum pressure required to account for pressure drop and load-unload differentials.

• Then combine the consumption capacity of all your equipment; this will be the required capacity of your air compressor. It is recommended to buy a bigger air compressor that your total capacity to ensure the capacity is wholly met and account for your needs' future expansions.

Contact Us

It's important to ensure you select the right rotary screw compressor for your needs. So, if you have any questions or need some help please do not hesitate to call us on 1300 998 647