Rotary Screw Compressors: Maintenance Best Practices for Enhanced Performance

Unplanned compressor downtime drains money, time, and resources. The unpredictability of a breakdown can drastically delay production and lead to substantial financial loss.

Rotary screw compressors are one of the most commonly used air compressors for industrial settings. They are powerful, customizable, and designed to run at 100% duty cycle. 

However, even the highest-performing compressors experience wear and tear. Ignoring routine maintenance leads to problems ranging from minor issues like pressure fluctuations to major breakdowns that halt production and incur serious expenses. 

Consistent maintenance helps avoid unplanned downtime and extend the life of your equipment. We’ve put together a summary of best practices to guide you through understanding proactive maintenance for your rotary screw compressor.

 

When to Perform Maintenance Checks

Some maintenance checks should be performed daily by you or your staff, including:

• Check compressor oil level (for oil-injected compressors)
• Inspect for leaks (air, moisture, and oil for oil-injected compressors)
• Verify proper operation of controls and indicators
• Check the air filter for blockages
• Monitor temperature readings
• Observe for unusual noise or vibration
• Examine safety relief valves for signs of activation or tampering
• Inspect hoses and connections for wear or damage
• Review operating pressure levels
• Check condensate traps 
• Look for noticeable signs of damage

Schedule more in-depth checks on a routine basis, after the manufacturer’s recommended hours of use, or as soon as you notice unusual performance or noises from your system. 

Air Handling Equipment (AHE) has been in the compressed air business for over 45 years and services all compressor makes and models. We’ve seen our fair share of unusual maintenance issues, but we’ve also identified best practices that apply to rotary screw compressors regardless of the manufacturer. 

 

Maintenance Best Practices for Oil-Lubricated Rotary Screw Compressors

Various industries widely use lubricated rotary screw compressors due to their efficiency and reliability. Some of the most common maintenance issues affecting air ends, drive trains, and system performance include:

1. Oil and Oil Filter Contamination

Check: Regularly inspect oil for signs of contamination or degradation such as a milky appearance (water contamination) or particulate matter. Check oil filters weekly for signs of clogging or damage.

Fix: Change the oil per the manufacturer’s recommendation, usually between 2000 and 8000 hours of operation. Follow the manufacturer’s instructions for replacing oil filters.

2. Oil Leaks

Check: Inspect all seals, gaskets, and hose connections periodically for signs of oil leaks.

Fix: Replace worn or damaged seals and gaskets. Tighten fittings appropriately.

3. Air Filter Clogging

Check: Monitor the pressure differential across the air filter and visually inspect it for contaminants. Dirty or clogged filters force the compressor to work harder.

Fix: Clean or replace the air filter when it becomes clogged or reaches the end of its expected service interval.

4. Air/Oil Separator Failure

Check: Monitor the oil carryover levels in the compressed air and check the separator’s pressure differential. Look for sludge (oil mixed with water) buildup around filters, coolers, and the compressed air system.

Fix: Replace the separator element when performance drops or according to the maintenance schedule. Clean sludge from the compressor and check dryer filter conditions along with the oil/water separator.

5. Worn or Damaged Bearings and Belts

Check: Listen for unusual noises and check for excessive vibration, which could indicate a problem with bearings or belts.

Fix: Replace worn or damaged bearings and belts and adjust the tension when needed.

6. Heat Exchanger Fouling

Check: Monitor the temperature of the compressor’s discharge air. An increase could signal heat exchanger fouling (buildup of unwanted material).

Fix: Clean the heat exchanger surfaces according to the manufacturer’s instructions, which may involve chemical or mechanical cleaning methods.

7. Improper Lubricant Level or Quality

Check: Use dipsticks, sight glasses, or electronic sensors to regularly check oil levels, and visually inspect the oil quality.

Fix: Fill or replace oil with the correct grade and type specified by the manufacturer. Perform periodic oil analysis for proactive maintenance.

8. Inadequate Ventilation

Check: Inspect the space around the compressor for adequate airflow and check for any obstructions that could hinder proper ventilation. Look for excess condensation in or around the drip tray.

Fix: Remove obstructions or anything disrupting ventilation clearance around the system. Clean ventilation grills or fans for optimal functionality.

These maintenance checks provide a starting point for troubleshooting compressor issues on your own. Refer to the compressor’s manual for specific maintenance recommendations, or call one of our AHE technicians for professional support.

 

Oil-Free Rotary Screw Compressor Maintenance

You won’t have oil-related issues with an oil-free compressor. However, the compressors function similarly to each other so it’s not uncommon to have many of the same problems. Common maintenance issues, checks, and fixes for oil-free rotary screw compressors include:

1. Excessive Heat

Check: Oil-free compressors generate more heat without oil to cool or seal the compressor. Monitor the temperature difference between the inlet and outlet air and look for low coolant levels. Listen for unusual or loud noises such as grinding, buzzing, or rattling. 

Fix: Inspect all parts of the cooling system, including air filters, coolers, fins, and vents. Clean, repair, or replace as necessary and according to manufacturer guidelines.

2. Motor and Drivetrain Issues

Check: Listen for abnormal sounds from the motor or drivetrain. Keep an eye out for overheating and vibration.

Fix: Periodically test the motor electricals and replace any worn components in the drivetrain, like belts. Ensure proper alignment and tension.

3. Air or Moisture Leaks

Check: Regularly inspect all hoses, valves, and connections for signs of leaks.

Fix: Tighten connections and replace any damaged hoses, O-rings, or seals.

4. Rotor Coating Wear

Check: To mitigate the lack of oil, the rotors in oil-free compressors are often coated with materials like Teflon to minimize friction. Schedule regular inspections of the rotors and their coatings for flaking or uneven surfaces.

Fix: Follow the manufacturer’s recommendations to recoat or replace rotors if wear is detected. We highly recommend contacting a professional whenever the air end needs to be opened, including rotor coating inspections.

5. Rotor Misalignment

Check: Listen for abnormal noises or vibrations during operation. 

Fix: Use laser alignment or vibration analysis tools to check for misalignment or damage. Visually inspect for unusual abrasions or excess debris around misaligned areas. Rotor misalignment also occurs in the air end, so we recommend contacting a professional for support.

6. Air Purity Issues

Check: Conduct regular air quality tests. Inspect filters, seals, and gaskets for integrity and efficiency.

Fix: Replace air filters, seals, and gaskets as needed. Implement enhanced filtration systems if environmental conditions warrant.

7. Compression Chamber Corrosion

Check: Inspect internal components for signs of corrosion during scheduled maintenance intervals, focusing on the compression chamber and any moisture-prone areas.

Fix: Apply corrosion-resistant coatings and consider environmental control solutions like air dryers to reduce humidity exposure.

8. Underperforming Dryers (if the system includes a dryer)

Check: If you start noticing issues, check the inlet air temperature going into the air dryer. Monitor the pressure and quality of outgoing air for moisture content.

Fix: Replace or regenerate the desiccant material in desiccant dryers when necessary. Clean the heat exchanger and reposition or replace bypass valves. 

In both types of compressors, it’s important to regularly check electrical connections for any signs of overheating or corrosion.

 

Gardner Denver Rotary Screw Compressors

Air Handling Equipment represents the Gardner Denver complete line of lubricated and oil-free rotary screw compressors. As an example of their advanced oil-free rotary screw compressor technology, the Gardner Denver Ultima pushes the boundaries with its enhanced performance metrics. It is engineered to be up to 13% more efficient than conventional two-stage oil-free compressors and has 98% heat recovery. 

The Ultima compressor showcases the benefits of proper maintenance, as its cutting-edge design includes a smart control system meant to optimize operation and maintenance schedules. Partnering with Air Handling Equipment for Gardner Denver rotary screw compressors offers peace of mind that you’ll be backed by an industry-leading manufacturer and exceptional professional support.

Schedule Preventative Maintenance with Air Handling Equipment

We’ve covered a lot of information in this blog about how to maintain your rotary screw compressor. Simplify the process by calling our professionals to do the maintenance checks for you!

Preventative maintenance is an investment in your equipment’s ongoing productivity and efficiency. We create customized maintenance plans by considering factors like operating hours, environmental conditions, and manufacturer’s recommendations. Check out our compressed air maintenance plans to learn more about creating a schedule that’s convenient for you.

Reduce energy consumption and operating costs by scheduling preventative maintenance with Air Handling Equipment.

Contact us or call 1-800-736-3321 for 24/7 support in central, midwestern, or southern Ohio and northern Kentucky!