The PROS Company PROfurbishing

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Quick Turnaround. ◇ Custom ... make an informed decision on whether to rebuild an air end or to replace it. ... condit
The PROS Company Professional Rebuild & Optimal Service, LLC PROFURBISH The art of reconditioning a piece of equipment to a higher standard and quality.

SPECIALIZING IN PROFURBISHING Screw Compressors / Air Ends Rotary Vane Compressors Gear Boxes Vacuum Pumps Liquid Ring Blowers Repair Sealing Strips Dynamic Balancing Repair of Damaged Internal Parts New Seals, Gaskets & O-rings

The PROS Company Also Provides: New and Reman Compressors Quick Turnaround Custom Engineering Exchange Programs

ANY BRAND, MAKE, or MODEL of COMPRESSOR The PROS Company www.thePROSco.com 601 Texas Avenue Lubbock, TX 79401 Office: (806) 749-PRO1 (7761) Fax: (806) 749-PRO2 (7762) Lee Levisay (405) 830-0PRO (0776) [email protected] Tom Logsdon (806) 316-2565 [email protected] Terry “TL” Ledbetter (806) 789-6338 [email protected]

The PROS Company Solves Problems! The PROS Company is proud to announce an alliance with the largest filter manufacturer to solve filtration and separation problems. If you are having a problem with your air end or screw compressor, call your PROS professional and we will be happy to solve your problem. We would like to take this opportunity to work an exchange program with you to eliminate downtime waiting on a PROfurbished unit. Call us to discuss how we can help improve your bottom line. Read the article in :

Air Compressor Best Practices July 2012 issue, Page 22

The Art of Air End Forensics http://www.airbestpractices.com/technology/air-compressors/ art-air-end-forensics

The PROS Company is committed to

PROfurbishing all equipment that is trusted to their expert team of PROfurbishers.

The Art of Air-End Forensics By Lee Levisay, The PROS Company

When you send your air-end to a company to have it rebuilt, do you get a piece of paper with no more information on it than what it is going to cost to rebuild or do you get a full technical evaluation, complete with photos, showing the damage inside your air-end and explaining what needs to be done regarding repair? There is a company out there that is now giving you this choice. The PROfessionals at The PROS Company out of Lubbock, Texas, does a full technical evaluation on every air-end reconditioned. They will furnish you photos and give an explanation of the damage and what will need to be repaired.

the mated side faces of the two outer rings. Solid particle contamination and related damage could account for the excessive vibrations from the equipment, but the source of vibration may be unrelated to the bearings.

Both bearings display evidence of solid particle contamination. Dents and scratches are present in the load zones of both rings. Some of the dents are smooth bottomed, while others exhibit rough bottoms. These conditions indicate that some of the particles had ductility but others exhibited brittle behavior. Damage to the rolling elements also supports the presence of solid particles in Clues Explain Root Causes the bearings. The balls scratched and the rollersDents exhibit Both bearings display evidence of are solid particle contamination. and The art of air-end forensics is actually more of a science scoring and pronounced grooves. The scoring and grooves scratches are present in the load zones of both rings. Some of the dents are smooth while rough bottoms. These conditions than an art. It takes years of experience and knowledgebottomed, of on theothers rollersexhibit are typically due to particles that areindicate forced that som of the particles had ductility but others exhibited brittle behavior. Damage the interworking of air ends to be accurate. Air ends do through or become lodged in the cage pockets. Several of to the rolling elements also supports the presence of solid particles in the bearings. The not have a lot of pieces, but the pieces they do have are the cage ribs do have embedded metal particles. Since there balls are scratched and the rollers exhibit scoring and pronounced grooves. The specialized and rotate at high speeds with close tolerances. is grooves no spalling in rollers these bearings anddue neither cage isthat broken scoring and on the are typically to particles are forced When the smallest thing goes wrong, you can have a major excessively the source the particles must through ororbecome lodgedworn, in the cage pockets.ofSeveral of the cage ribsliedo have problem. There are always clues to what went wrong. the bearing. embeddedoutside metal particles. Since there is no spalling in these bearings and neither cage is broken or excessively worn, the source of the particles must lie outside the Putting all the clues together and presenting the results in bearing. a technical evaluation is most important to being able to A few small galled patches are present on one side face of make an informed decision on whether to rebuild an air each outer ring. Galling is an adhesive wear mechanism that A few small galled patches are present on one side face of each outer ring. Galling end or to replace it. causes material to be that pulled frommaterial one surface deposited is an adhesive wear mechanism causes to be and pulled from one surface on the as one surface moves relative totothe and deposited on other the other as one surface moves relative theother. other.The The can be misinterpreted as arcing damage. The galling damage It is always interesting to see what you will find insideappearance of appearance can be misinterpreted as arcing damage. The features on the faces of these two rings are mirror of each This and an air end when you disassemble it. Looking for clues and galling damage features on theimages faces of theseother. two rings are the outline of notches on the cylindrical roller bearings side face establishes that the taking photos is vital for a good forensic report. A small mirror images of each other. This and the outline of notches bearings were mounted against one another. scratch or discoloration of metal could tell you the story on the cylindrical roller bearings side face establishes that about the history of the air end. Sometimes it takes further the bearings were mounted against one another. analysis with a microscope to tell the full story. We once had an air end and the bearings showed the classic pattern of electrical arcing as the cause of the failure. We decided to send the bearings to the manufacturer for further analysis. The manufacturer did microscopic analysis on them and found two different solid particle contaminates in the bearing causing the visible damage. This completely changed the results of the technical evaluation and showed that external contamination was the real culprit. Below is the conclusion to the report from the bearing manufacturer.

Bearing Report Conclusions

No evidence of electrical arcing appears in or on these bearings. Indentations on the raceways may have been mistaken for arcing damage. Another feature that could be misconstrued as arcing damage is small galled patches on

Scratches on roller bearing arcing Scratches on roller bearing arcing

Chemical corrosion evidence on the bearings

Scratches on bearing

Scratches on bearing Scratches on bearing

Liquid metal evidence of chemical corrosion Liquid metal evidence of chemical corrosion

Scratches on roller bearing Scratches on roller bearing

Corrosion on the bearing and bearing race With Reports Like This, the Full Story is Told. Scratches on roller bearing Corrosion on the bearing and bearing race Reports Like This, the Full Story is Told. Other not so common problems are chemical corrosion The meshing of the rotors is another place where very tight issues. Some air-ends we have reconditioned have evidence so common problems are chemical corrosion issues. Some air-ends we have reconditioned havetolerances evidence of are of great importance. If external contamination Reports Like This, the Full Story is Told. of chemical corrosion from the environment they are orrosion from the environment they are exposed to. The damage is more of a pitting and flaking on the enters the air end, there is a high possibility that there will exposed to. The damage is more of a pitting and The flaking on meshing of the rotors is another place where very tight tolerances are of great importance. If external so common problems are chemical corrosion issues. Some air-ends we have reconditioned have evidence of hen scratching and scuffing. be damage to the rotors. Scarring, pitting, and normal wear the bearings then scratching and scuffing. contamination enters the air end, there is a high possibility that there will be damage to the rotors. Scarring orrosion from the environment they are exposed to. The damage is more of a pitting and flaking on the of the rotors will make the air end less efficient. Excessive and normal wear of the rotors will make the air end less efficient. Excessive damage to the rotors will turn t hen scratching and scuffing. damage to the rotors will turn them into scrap iron. New scrap iron. New sealing strips can be put on rotors, but damage to the rotor profile is less likely to be repair sealing be putdamage on rotors, but damage toadvancement the rotor in weldin conjunction with damage to thestrips rotors can is normally to the housing. With the profile less likely to technical be repairable. with and descri procedures, most housings areis repairable. A good evaluationIn willconjunction have detailed photos damage to the rotors is normally damage to the housing. the damage and what needs to be repaired. With the advancement in welding procedures, most housings are repairable. A good technical evaluation will have detailed photos and descriptions of the damage and what needs to be repaired.

Chemical corrosion evidence on the bearings Chemical corrosion evidence on the bearings

end, damage will occur. The excess heat will cause thermal of the removed rotors. The rotors will then start toand rubour oversized dril haveexpansion to be surgically with a custom-made saw

the housing in many different places. Most common is the the discharge andhousing, the interior of the triesair togap, press the rotor outface of the he/she willrotor break the housing and m housing.

here very tight tolerances are of greatWhen importance. externalexcessive heat leaves many different clues. Burnt oil residue looks like molasses and will be doing theIfforensics,

igh possibility that there will be damage to the rotors. Scarring, pitting,off by moving parts. As the rotors continue to heat up and expand, they will in every nook and cranny not scraped

air end less efficient. Excessive damage to into the rotors them into come contactwill withturn the housing. This will create more heat buildup and damage. Then there will be evidence of

parts scraping each other. If the air end is not shut down, the heat will build with more thermal otors, but damage to the rotor profilemetal is less likely to beagainst repairable. In

expansion of the housing and rotor, thus eliminating any close tolerances that were there. The metal will liquefy and mally damage to the housing. With the advancement in welding

when thephotos unit does stop rotating, good technical evaluation will have detailed andfinally descriptions of the liquefied metal will weld the rotor and housing together, locking the unit up and resulting in a catastrophic failure. Forensic evidence is really obvious at this point. The air end rotor will then have to be surgically removed with a custom-made saw and our oversized drill press. If the inexperienced rebuilder tries to press the rotor out of the housing, he/she will break the housing and make the air end owner buy a new one.

Burnt oil on bearing

Damaged Rotors

Burnt oil on bearing

Damaged Rotors

Damaged Rotor Housing

Burn

Sometimes what is not there is just as important as what is there. We have fou

rebuilder forgot to install or maybe thought was not important. Most common

shims installed instead of making a spacer. The most comical was a combinat

same sizes) that replaced a spacer that was almost 3/8 of an inch in thickness

An effective manager will take the information provided from the technical ev

problems or to improve on the preventative maintenance program. One custo

put the technical evaluation in the file each time it is rebuilt to compile a more

Burnt oil residue in oil port Burnt oil on bearing

Here is an actual Burnt response a customer on the technical evaluation and re oil from residue in oil port

Sometimes what not therethis is just aswork important as Get what analysis. We canissell & justify kinda every time! er' is dun! Thx!!!” Damaged Rotor Housing there. We have found missing parts that a previous rebuilder Damaged Rotor Housing toisother managers customers if you able to fully inform them when the Sometimes what is not there is just as important as what there. We haveor found missing partsare that a previous forgot to install or maybe thought was notWe important. Most rebuilder forgot to install or maybe thought was not important. Most common are spacers and seals. find multiple With air compression and rotating parts, heat is generated common are spacers and seals. We find multiple shims shims installed instead of making a spacer. and is a constant companion. The oil-flooded air end uses The most comical was a combination of washers and shims (not all the installed instead of making a spacer. The most comical the oil to help control same the heat removea spacer it from sizes) and that replaced that the was almost 3/8 of an inch in thickness. was a combination of washers and shims (not all the same air end. When this balance is upset and heat builds up in sizes) that replaced a spacer that was almost 3/8 of an inch the air end, damage willAnoccur. The excesswillheat cause effective manager take will the information provided from the technical evaluation and use it to prevent similar in thickness. thermal expansion of the rotors.orThe rotorson will start maintenance program. One customer keeps a file on each air end and will problems to improve thethen preventative to rub the housing in many different places. Most common put the technical evaluation in the file each time itAn is rebuilt to compile a morewill complete effective manager takehistory. the information provided is the air gap, the discharge face and the interior of the rotor from the technical evaluation and use it to prevent similar housing. or to improve on the preventative Here is an actual response from a customer on theproblems technical evaluation and resulting quotation - “Anothermaintenance VERY good program. One customer keeps a file on each airto end analysis. We can sell & justify this kinda work every time! Get er' dun! Thx!!!”. It makes your job much easier justifyand When doing the forensics, excessive heat leaves many will inform put the technical inapproval the filetoeach other managers or customers if you are able to fully them when the evaluation time comes for spendtime it is different clues. Burnt oilto residue looks like molasses and rebuilt to compile a more complete history. will be in every nook and cranny not scraped off by moving parts. As the rotors continue to heat up and expand, they Here is an actual response from a customer on the technical will come into contact with the housing. This will create evaluation and resulting quotation - “Another VERY good more heat buildup and damage. Then there will be evidence analysis. We can sell & justify this kinda work every time! of metal parts scraping against each other. If the air end Get er’ dun! Thx!!!”. It makes your job much easier to justify is not shut down, the heat will build with more thermal to other managers or customers if you are able to fully expansion of the housing and rotor, thus eliminating any inform them when the time comes for approval to spend close tolerances that were there. The metal will liquefy and money that may have been budgeted for something else. A when the unit does finally stop rotating, the liquefied metal well-written technical evaluation with good forensic data is will weld the rotor and housing together, locking the unit a valuable tool to have in your toolbox. up and resulting in a catastrophic failure. Forensic evidence In summary a well-prepared technical evaluation will have is really obvious at this point. The air end rotor will then lots of photos of the forensic evidence and good descriptions have to be surgically removed with a custom-made saw of the damage. With this information, the decision maker is and our oversized drill press. If the inexperienced rebuilder much more informed to make the best economical choice tries to press the rotor out of the housing, he/she will break for the company. The technical evaluation is a tool that will the housing and make the air end owner buy a new one. create a win-win situation for all involved. For more information please contact Lee Levisay, The PROS Company, tel: 405-830-0776,www.thePROSco.com