Considerations for Maintaining Compressed Air Dryers

Compressed air dryers have become an integral part of most compressed air systems today.  They help prevent product spoilage, equipment malfunction and system failure.  Although they are an important piece of your compressed air system, it’s easy for them to be overlooked until a problem arises.  Here is a short list of items to keep an eye on to ensure your downstream air is clean and dry.

Refrigerated Dryers:

  • Temperature Checks – Ensure the inlet and ambient temperatures are within the acceptable ranges for your specific dryer.
  • Condenser Coil – With an air-cooled dryer, it is important to clean off accumulated dust and dirt nano compressed air dryersmonthly, and in dirtier environments, remove debris every two weeks. Water cooled units usually have a strainer that needs to be inspected and cleaned monthly.
  • Moisture Separator / Coalescing Filter – Should be checked monthly to ensure proper operation. If equipped with an internal element, it should be replaced at least annually or when the pressure drop becomes excessive.
  • Condensate Drain(s) – Should be checked daily to ensure the condensate is being discharged from the unit. Most electric and zero loss drains are equipped with a test button.  If a standard internal float drain is being used, it should be replaced annually.

Desiccant Dryers:

  • First and foremost, desiccant dryers are pressure vessels. Make sure all safety procedures are followed when inspecting or servicing this type of equipment.  Always de-pressurize before servicing.
  • Coalescing Pre-filter – Removes any remaining oil and water aerosols before the air hits the desiccant bed to prevent saturation and oil contamination. Check the drain mechanism on this filter daily.  The element should be replaced every 6-12 months.
  • Particulate After-filter – Prevents downstream air system from being exposed to desiccant dust. Element should be changed at least every 12 months.
  • Desiccant – Should be replaced whenever the required dew point can’t be maintained if operating conditions are correct and there are no other mechanical issues. Desiccant life is determined by the quality of the inlet air.  Installing and maintaining a proper Coalescing Pre-Filter will extend the life of the desiccant.
  • Purge Mufflers – Should be checked regularly and changed annually. Desiccant dust can clog muffler elements over time, creating back pressure and restricting purge flow.
  • Valves – Every “adsorption” type desiccant dryer is different in design, but they all have to switch towers and regenerate during normal operation. Always inspect the switching valves and purge valves for proper operation and follow the manufacturer’s guidelines on preventative maintenance for these valves.

If you need help maintaining these or any other parts of your compressed air system, we are here to help.  From training your own personnel, to full maintenance contracts, we welcome the opportunity to be your partner is success.  Contact us today!

Compressed Air Dryers and Moisture Content

nano compressed air dryersCompressed air is commonly referred to as the 4th utility, which is why facility managers are concerned with the quality and moisture content of the air going into their plant. High levels of moisture (water and oil) can cause premature wear on tools, cylinders and valves as well as increase corrosion and bacteria/mold growth inside the piping network. Installing a compressed air dryer will drastically reduce the moisture content and eliminate these problems; however, selecting the correct dryer technology is important.

Refrigerated style compressed air dryers are common and operate similarly to an air conditioning unit by cooling the incoming compressed air, condensing water vapor into liquid and then removing through a separator with a drain valve. Refrigerated dryers are limited by temperature and cannot cool below 32°F (0*C), as the condensed liquid would freeze. Pressure dew point is defined as the temperature at which water vapor condenses into a liquid at a given pressure. Based on this definition, a refrigerated dryer will deliver a pressure dew point range just above 32°F. As a reference, compressed air at 38°F pressure dew point and 100 psig pressure contains 609 ppm(w) of moisture.nano compressed air dryer

There are several different types of refrigerated dryers including non-cycling, cycling and variable speed dryers.  Each technology refers to the operation of the refrigeration compressor. The compressor runs continuously in a non-cycling dryer, independent of the thermal load. Similar to your home refrigerator or air conditioning unit, a cycling dryer turns the refrigeration compressor on and off based on a varying system thermal load. Your home is the thermal mass for your air conditioning unit which allows the compressor to cycle on and off. Cycling compressed air dryers utilize a thermal mass such as silica or glycol to cycle the refrigeration compressor and a variable speed drive compressor increases or decreases the speed and subsequent capacity of the compressor relative to the compressed air consumption.

To achieve a pressure dew point below 32°F, a different technology known as adsorption is required. Small beads or granules of desiccant material are extremely effective in removing moisture, similar to the small bags you might find in a new pair of shoes or jacket pocket. In the adsorption process, the desiccant media pulls the moisture out of the compressed air stream and holds it on the surface of the beads. Over time, the beads become saturated and require regeneration. During this phase of the process (commonly referred to regeneration or desorption), a portion of the dried air from the online tower/vessel is used to flow through the saturated tower to remove the moisture. As a reference, compressed air at a -40°C/F pressure dew point and 100 psig pressure contains 10 ppm(w) moisture content and meets ISO 8573 class 2.

The ISO 8573 group of international standards is used for the classification of compressed air purity. The standard provides the test methods and analytical techniques for each type of contaminant. The table to the left summarizes the maximum contaminant levels specified in ISO 8573.1: 2010 for the various compressed air quality classes.

Nano R1-Series (NXC) thermal mass refrigerated dryers utilize a reliable, simple and energy-efficient stationary silica mass dryer design to achieve a 38°F pressure dew point (ISO Class 4 moisture vapor). If you require a lower pressure dew point for high technology lab or process applications, the nano D-Series (NDL, NHL, NEX and NBP) utilize highly efficient desiccant and advanced controls to effectively remove moisture content down to a -40°C/F pressure dew point or lower (ISO Class 2/1 moisture vapor). Contact your local compressed air professional at Lewis Systems to find out which dryer technology is right for your specific application at your facility.

 

Guest post written by: Mark Lauterwasser, Business Development Manager at nano purification solutions. For more information, visit www.n-psi.com

 

Preparing Compressed Air Systems for Colder Weather

freezing pipes, preparing compressed air systems for cold weatherWith colder weather coming soon, compressed air systems that are subject to lower temperatures may deal with slow starting, possible control line freeze problems, and condensate lines freezing.  To help prevent some of these problems, heat lamps can be installed close to the lines to prevent freezing. Also, applying heat tracing to control and condensate lines will help.  However, keep in mind that anything installed on the lines themselves might have to be removed when the equipment is being serviced.  Here are a few quick tips:

  • Check insulated areas and make sure the heat is staying inside and the cold is staying outside.
  • Also check any weather stripping and replace areas that are worn out and not working properly.
  • Check condensate drains throughout your system for proper operation. Excess water in your lines and freezing temperatures are not a good mix.
  • Check your air intake openings to ensure they are adequately protected from increased rain and snow.

Contact us today if you need any help with addressing your cold weather vulnerabilities.

 

Written by: Keith Seawell, Service Manager – Greensboro branch.  Keith has been with Lewis Systems over 30 years.  

 

Kobelco KNW Series Unique Features

kobelco knw oil free air compressor

Recently we looked at some of the benefits of switching to Oil-Free compressed air.  Moving to an Oil-Free compressor can have a significant impact on your cost of ownership, but like most capital expenses, you’ve got to do your research before you buy.  Let’s take a look at the Kobelco KNW Series and see what unique features set it apart from the competition.

Kobelco KNW Series Oil Free Air Compressor

kobelco knw series oil free specs

  • Heavy Duty Air End Design – a patented, high-efficiency super rotor profile. Rotors, shafts and compression housing all have a PTFE coating to protect against corrosion and wear.  Thrust balance pistons on each stage provide maximum air end life.  These are not found on competitive models.
  • Pre and Post Lubrication of Gears & Bearings – an independent motor-driven gear pump provides lubrication prior to start up, during operation and shutdown. A unique feature of the Kobelco KNW Series that increases gear and bearing life.
  • Heavy Duty Input Bull Gear – input bull gear is supported on each side along with a labyrinth type seal used on the drive end. Competitors use an overhung design as well as lip seals, which are prone to wear and leakage.  The KNW design ensures a long operating life and eliminates oil leaks.

If you’re looking for a quality oil free brand, Kobelco KNW should be at the top of your list. Learn more about the KNW series here.

Common Types of Air Compressor Repair

Lewis Systems & Service Co., Inc. not only sells new and used air compressors but a good part of our business is servicing and repairing air compressors. Below is a list of some common air compressor repairs that we address in the field. This is not a trouble shooting guide or instructions on how to do repairs, however if your unit is serviced on a regular basis, a lot of these problems can be prevented.

Reciprocating Compressors:GAR_PureAir_II_DUPLEX

  • Rings – As the piston rings wear out, excessive oil consumption will rise.
  • Valves – Carbon deposits can build up on the valves causing the compressor to take longer to build up pressure. They usually need regular cleaning or replacing if damaged.
  • Controls – Defective pressure switch can cause starting problems as well as a faulty check valve. Problems with the pilot valve can cause the compressor not to unload properly.
  • Belts can be too tight or too loose, also the pulley could be out of alignment causing excessive wear on the belts.
  • Air intake filters should be inspected and changed on a regular basis. Dirty air filters can cause long pump up times and overheating.
  • Routine Maintenance Items: Changing the air filter and oil on a regular basis will prevent many problems. It will also extend the life of valves and rings.

Rotary Screw Compressors:HitachiDSP55a

  • Controls / Check Valves: The majority of problems that arise on rotary screw compressors are related to the controls and sensors. A faulty pressure transducer or a sticky thermal valve element can shut your compressor down very quickly. It’s always good practice to have these items in stock or at least know a reliable service center (we suggest Lewis Systems), that normally has these items in stock.
  • Not Building Pressure: Number one cause: a dirty inlet air filter. Also problems with the inlet valve or minimum pressure valve. Both should be inspected and cleaned on a regular basis. Both normally have packing rings or seals that need to be replaced occasionally.
  • Inlet Valve Maintenance
  • Excessive Oil Carryover: A common cause for oil carryover is a blocked or faulty scavenge line check valve. Oil separators can rupture if they are not changed on a regular basis which will cause oil carryover as well.
  • Routine Maintenance Items: Changing the air filter and oil filter on a regular basis will prevent many problems. It will also extend the life of the compressor lubricant and oil cooler.
  • As you can see, there are lots of maintenance and repair issues that should be addressed on your air compressor. Don’t forget that Lewis Systems & Service Co., Inc. has a fully staffed service department at each of our locations to assist you. From emergency repairs to proactive maintenance agreements we can help keep your plant up and running.