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Rotary Screw Compressor: Components, Operation, and Maintenance

Displacement Compressors Air compressors Compressor Types Compressed Air Wiki Other Compressors Rotary screw compressors

In this guide, we'll break down the essential components that make up a rotary screw compressor. See what each component does and how it works and learn how to properly maintain your compressor for optimal performance and longevity.

What essential components make up a screw compressor?

When buying a screw compressor, it is important to be aware of the essential components for a properly functioning rotary screw air compressor. Here is a brief list of the essential parts and functions:

  1. Inlet suction air filter: Set at the inlet of the compression chamber where it's possible to catch and reduce dust and ingress of damaging particles. Necessary for cleaning and protection of the compressor stage/s.
  2. Suction valve or load/unload valve: This valve is usually set at the top of the compressing unit. It's responsible for drawing the raw air inward to be processed by the rotary screw element. Opens fully when system pressure drops below the minimum set limit (loading) and closes the valves (unloading) when the system pressure reaches the maximum set limit.
  3. Rotary screw element: Drives the air to the outlet and creates pressure.
  4. Compression chamber: Encloses the rotary screw element. It's possible to have multiple stages for more pressurization.
  5. Anti-friction roller and ball bearings: These secure the rotary screws, making sure they are balanced and rotated evenly.
  6. Oil filter: Oil filters are set within the oil system to gradually remove contamination in the oil that is used for lubrication or compression.
  7. Separator vessel: This is a tank where compressed air is sent for the separation of oil from compressed air. It also serves as a reservoir for oil and holds air pressure with the aid of the min pressure valve to ensure lubrication pressure is maintained within the system.
  8. Separators: Specifically for oil-injected compressors, it is embedded inside the separator vessel and filters the excess oil to ensure that the compressed air leaves the system with a minimum residual oil content.
  9. Gaskets and seals: Necessary to maintain maximum pressure and make sure the overall compressor is leak-free at critical points in the unit.
  10. Non-return valve/check valve: This valve ensures that when the compressor unloads or stops generating air, it retains the pressure in the downstream system.
  11. Compressor motor: This drives the rotary screws and powers the unit's compression cycle. It is controlled by the compressor microprocessor controller.
  12. System control: This takes the form of a display and input panel. Necessary for operating, automating, and monitoring the compressor unit.
  13. Discharge valve: This is usually set at the end of the compression process. It only opens once the correct minimum pressure is achieved and ensures enough pressure is maintained within the system to ensure good lubrication of the compression stages.
  14. After cooler: This cools down the compressed air and removes the heat generated by the compression process. The coolers can be either cooled by ambient air or with water-cooled compressors. The selection of either air cooling or water cooling is made based on individual customer requirements and the location of the installation.
  15. Water separator: One of the critical screw air compressor components, the water separator is installed downstream of the aftercooler and separates liquid moisture from compressed air and ensures air leaving the compressor is saturated and free of any liquid water.

How rotary screw compressor parts work?

Understanding the function of rotary screw air compressor componentts will help you optimize the performance of your equipment by replacing and maintaining them as and when needed. 

Rotary Screw Compressor Parts

1. Inlet Air Filter

These are required for regulatory maintenance and an important component of a compressor. When it comes to oil-injected units, the air filters clean up moisture and oil residue from the opening valve and cooling injection processes. Regular inspection of air filters is crucial for your equipment’s performance.

Air filters are located near the intake valves for the oil-free units. They form the primary defense line from pressurized air impurities and are thus the most common maintenance filters.

2. Rotary Screw Element

Interlocking twin rotors are placed inside lined cylinders wherein their complementary and circulatory rotations occur. As soon as the machine is switched on, rotors will operate, receiving suctioned air from the opening valve. Connected to the compressor’s motors, rotors will start spinning through a wide distribution system of belts, bearings, and the motor drive. Air is sucked and compressed between the rotors while the spinning continues.

The air will be transformed to a fully compressed state once the grooves will reach the finishing of the rotation length. Lastly, the compressed air will be released through the discharge valve into the storage tank.

3. Oil Filter

Oil filters help keep the compressed air’s gas purity clean and intact and ensure proper lubrication and cooling functions of the entire machine. Belt and pulley run in sync with those nestling within the oil separator. Also, since contemporary oil filters have a spin on installation, they are easy to assess and replace.

Most oil filters are equipped with bypass valves that send alerts when oil filters are too jammed or internal operating temperatures are hot. They will allow raw oil to infiltrate the compression chamber but without entering the oil filters.

4. Bearing

Bearings help in reducing friction, balancing part movements, regulating the overall compressor’s temperature. Although there are several bearing nested in crucial places, axial and radial-load bearings are the most important among all. Radial-load bearings help ensure the compressor’s smooth rotations and horizontal circular roller motions without creating noises. Axial bearings keep the complementary and perpendicular spinning of the rollers in load and balanced.

5. Suction valve

Suction valves get triggered by your machine’s programmed stage settings to close and open, which ensures the efficiency of the rotary screw units. As they are engineered to suit different design elements for maximizing airflow, suction valves are available in different configurations. The poppet valve, the ring valve, and the plate valve are the three types of suction valves. Each of them has its distinct concentric layers to ensure ideal air flows for specific operation types.

6. Discharge valve

Being the endpoint of your compressor system, the discharge valves offer a safe and steady release of pure and fresh concentrated air. Whether the air is released into the final storage tank or connected to the air hoses, the discharge valve serves as the critical regulatory agent. Inspecting these valves and their performance is important to avoid any kind of malfunctioning.

7. Compressor motor

It is important to remember that the bigger the motor the better the performance does not always hold true for ensuring optimal productivity. The horsepower generated and maintained by massive motors may court efficiency problems.

You would want to test your motors frequently and check if it’s being productive, thereby gauging the overall performance of your compressor.

8. System control

A compressor’s system and stage control can regulate, monitor, and track the machine’s performance by assessing functionality and checkpoints throughout multiple unit features.

Particular unit designs may have internal sensors for automatically powering off the motor upon the completion of a programmed cycle or when the storage container is saturated. This is a smart technological feature for high-capacity equipment pieces.

9. Oil separator

Some compressor models may need to infuse oil in their chambers for cooling and lubrication, but they also require oil separators to filter and wash off excess oil from compressed air.

High temperatures can be the natural by-product of an equipment’s compressor capabilities. This makes use of oil and coolant fluids necessary for accelerating the machine’s performance. But an oil separator makes sure oil does not get mixed with the final compressed air. Oil separators can be installed when it wears out or you have to optimize your equipment.

10. Gaskets and seals

Gaskets and seals boast an air-tight design to prevent leakage of compressed air. Chamber lining and bearing rings around compression rotors and bearings are as critical as any other big or major compressor parts. As they are oil-injected or self-lubricated, sliding seals reduce natural friction building between rotors.

How to maintain rotary screw air compressor parts?

Regulatory maintenance of compressor parts should not be seen as some burdensome chore. Instead, this task should be taken seriously if you want to extend the life of your air compressor. 

Air filter checks

These parts require thorough inspections as they are most commonly worn-out or replace parts of the compressor. Although they are easy to maintain and clean, complete filter replacement may be required after a period of optimal utilization. 

System control testing

A system controller can monitor your equipment by providing safety readings of load settings, tank capacity, and temperature checks. Moreover, it can control the entire production system automatically. Checking pre-set limits regularly is important to make sure that the motor shuts off or operates at low capacity and reads pressure levels correctly. 

Oil filter & separate inspections – When your rotary screw air compressor is oil-injected, inspecting daily oil levels can reduce wearing out from friction. 

Oil filter and separate inspections

When your rotary screw air compressor is oil-injected, inspecting daily oil levels can reduce wearing out from friction. 

Rotor compression inspections

Checking your compressor’s rotors is the key to optimize the productivity of the machine. You may use belt tension gauges for the activity level measurement. While high readings indicate that motor bolts should be loosened, low readings mean these components need tightening. 

Routine maintenance schedules

An in-depth compressor system check should be conducted every few weeks to keep the machine’s performance intact for a longer time. 

Not sure what type of rotary screw air compressor you need? Get in touch with Atlas Copco’s experts for personal advice and a tailored quote.

There are many reasons why rotary screw compressors are in such high demand: They are very versatile, reliable, efficient, quiet and there are many different versions of this popular allrounder. But which one is right for you? To help you find the optimal solution for your needs, this guide will outline the different technologies and what they have to offer. 

 

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