screw compressor maintenance

"datePublished": "2018-10-23", Remove the oil drain cap, and let the oil drain out. The following maintenance checklist examples are for VMAC air compressors, as of November 2020. Carrier screw compressors have minimal vibration. ROTARY SCREW COMPRESSOR MAINTENANCE . At the end of each working day, check the control panel displays on your air compressor to ensure that the readings are normal. They can also be categorized with medium flow and medium pressure compressors compared with other types of compressors on pressure /flow chart for compressor types. "@id": "https://www.quincycompressor.com/rotary-screw-compressor-maintenance-guide/" Perform these observations for each mode of operation, regardless of whether or not you run the machine at full load. OEM Solutions One of the biggest risks of an irregular air compressor maintenance schedule is the chance of sudden, unexpected emergencies. SFR oil-free scroll compressor for railway ... We take care of all your compressor maintenance, upgrades, repairs and even breakdowns for an all-inclusive price. ROTARY SCREW MAINTENANCE SCHEDULE . Common rotary screw air compressor disadvantages are: Upfront cost; Skilled maintenance required; The number one reason people choose a reciprocating air compressor over a rotary screw is the initial cost. Screw compressors custom made by BOGE have for decades been synonymous with efficient and reliable compressed air supply to trade workshops through to industrial companies. Haringa Compressor understands the importance of maintaining your Atlas Copco GA55 Compressor properly. Screw compressors … Every air compressor model is unique and will have its own maintenance schedule, which is typically available in the owner’s manual. For the oil to do its job properly, you must change the oil supply on a periodic basis. Some of the biggest problems with rotary air compressor motors result from the following problems: Without the right grade of grease in proper proportions, the metal bearings of a rotary compressor are left to grind against one another with every revolution of the motor. To know what kind of oil is best for the make and model of your air compressor, consult the user’s manual or contact the manufacturer. Routine maintenance keeps rotary screw air compressors healthy and working. Over the years that you use the machine, you could ultimately get a better return on your initial investment by inspecting the compressor on a regular basis. Eagle Series. A rotary air compressor consists of several key internal components that could wear down over time if you don’t give them due, timely inspections. "publisher": { You value your time and money, and so do we. … Routine maintenance can also help you turn your initial investment into an enormous return. Manufacturers who back their systems with warranties also expect operators to maintain their systems. In addition to the air/oil separator, a rotary screw air compressor contains two other filters — the oil filter and the inlet filter. When removing a part, be careful not to damage it. I have installed this compressor in Oct 2012, While starting in first few hours I came to know that vibration were quite high around 10 mm/sec which was generally around 4 to 5 mm/sec. Each of these filters must be inspected on a periodic basis to ensure optimal filtration and to prevent the spread of dirt and oily mist throughout the system. Rotary Screw Air Compressor. If the readings begin to deviate from the records despite a lack of adjustments, it is time to inspect your air compressor. To prevent overloading, keep track of the ampere draw. }, For more details call at 770-874-1570 or email us usa@boge.com. }, It is important and critical nature of your compressed air system to maintain production at its maximum uptime! ATLAS COPCO GA55 COMPRESSOR MAINTENANCE AND SERVICES AVAILABLE FROM HARINGA COMPRESSOR INC. ROTARY SCREW TECHNOLOGY FOR EVERY APPLICATION. The time that a compressor remains down and inoperable is productivity lost. Air compressors vary and are used in multiple industries, but all of them need preventive maintenance checks to ensure efficient energy distribution to appropriate equipment. Parts Plan. Here are some things you can do in between formal preventive maintenance(PM) visits on your electric screw compressor to extend compressor life and prevent downtime. However, a screw-type air compressor is a complex machine consisting of many moving (and non-moving) parts and components. "logo": { Ensure unit is off and disconnect from the power source; Ensure compressor is on a flat and level surface; Remove fill cap / plug; Place collection container underneath the oil drain cap. The earlier you identify a problem, the easier and less costly it is to remedy. Moreover, the gear drives must be freshly lubricated on a periodic basis to ensure smooth running at all times. Riem Italy is a company specialized in sale and assistance of compressors and air treatment machines, both new and reconditioned. Air Compressors Air Filter The air filter is the primary protection of the compressor from harmful dirt being ingested into the oil system. Watch our latest video to learn what can happen when you choose an air compressor provider that offers low-quality products and services. FIND YOU THE BEST COMPRESSOR. Check for the following issues during each inspection of the airend in your rotary screw air compressor: In a rotary screw air compressor, the drive train is the component that guides the motion of the internal mechanisms as a whole. Due to the complex nature of the compressor, safety, oil types, and the importance of reliable and efficient operation it is highly recommended you consult a trained and competent person before doing any maintenance to this type of equipment. Find out how Canfor Southern Pine as improved their operation by switching to Quincy Compressor. As a guide for these inspections, refer back to the records of previous days and months to ensure that the measurements remain consistent over time. "mainEntityOfPage": { Once the level drops, clean out the old oil and refill. If your owner’s manual does not have a clear maintenance schedule, check with the rotary screw air compressor’s manufacturer to … Air/Oil Separator The air/oil separator should be changed every 2000 hours, or when there is excessive oil vapor in the discharge air. Air compressors that are properly maintained perform better, last longer, and are less likely to break down. Ideally, you should check the inlet filters after every 2,000 hours of operation. refrigeration compressor,compressor,Mitsubishi Compressor,Bristol Compressor,HITACHI Compressor,Danfoss compressor to solve the problem of compressor samples an Screw air compressor maintenance JavaScript seems to be disabled in your browser. ROTARY SCREW COMPRESSOR UNITS MODELS 12 – 101 Form 070.410-IOM (NOV 2014) INSTALLATION - OPERATION - MAINTENANCE File: SERVICE MANUAL - Section 70 Replaces: 070.410-IOM (AUG 2014) Dist: 3, 3a, 3b, 3c lease check www.ci.comfrick for the latest ersion of this publication. Explore our inventory of rotary screw air compressors today. "image": "https://www.quincycompressor.com/wp-content/uploads/2018/11/1-rotary.jpg", As with any motorized machine, an air compressor will generally last longer when it is well-maintained and inspected according to a strict schedule. For best results, stick to the screw compressor maintenance checklist included in your instruction manual. When well-maintained, a rotary air compressor can provide thousands of hours of unimpeded performance. Intervals vary greatly from unit to unit: Rotary Screw Compressor Maintenance. ", When it comes to maintenance, focus on the parts. Find a Dealer Also make sure that the gauges are properly set according to the specifications of your make and model. For the full maintenance schedules for VMAC systems, including instructions on how to perform critical maintenance tasks, please visit VMAC’s website and download the applicable Manual. Although maintenance schedules vary between rotary screw air compressors, your maintenance schedule will look something like this*: *Always confirm the maintenance schedule for your specific air compressor system with your manufacturer. This article is for general reference only and does not replace any manufacturer’s maintenance schedule, including VMAC’s. All Rights Reserved. Sample the oil every two or three months to ensure that it retains the right color and consistency. Railway compressors. "@context": "https://schema.org", Periodic maintenance table for you to check. The earlier you identify a problem, the easier and less costly it is to remedy. Thus, like any other mechanical equipment, such as a car or a lawnmower, your rotary screw compressor requires regular maintenance. Monthly: Every month, or after every 160 hours of … Maximize your efficiency. When the weather is humid or the environment is dusty, perform the preceding steps twice weekly, or every 20 hours. Even just a few hours of downtime can result in untold losses. With consistent, periodic maintenance, you can pinpoint issues early and have them remedied almost immediately. "@type": "Organization", ROTARY SCREW COMPRESSOR MAINTENANCE. Vibration is a concern among compressors. Compressors tested and approved by TUV Rheinland Germany. Today, in thousands of installations worldwide, our oil injected screw compressors provide high integrity, low maintenance solutions for liquid chilling, direct refrigeration and gas compression applications. Manufacturers of every kind use it as an energy source, a transport medium and for processing. In many cases, a problem detected early … Also take record of the readings on the compressor, motor and gearbox. If complete disassembly and assembly of the compressor are required, please contact your nearest sales office or service center of MAYEKAWA. … Overall, you must prevent the following conditions from taking hold of the oil in your air compressor: Oils can last anywhere from 3,000 to 8,000 hours, but this depends on the type of operations in question. Screw Air Compressor Maintenance Manual Kaeser Free Books PDF books, here is alsoavailable other sources of this Manual MetcalUser Guide The Redesigned SX Rotary Screw Compressor Range ... - KAESER The Redesigned SX Rotary Screw Compressor Range From Kaeser Kompressoren Quiet, Compact And Efficient Applications Requiring Smaller Volumes Of Compressed Air Can Take … the assortment of DV Systems rotary screw compressor maintenance kits we offer makes for quick and easy maintenance, resulting in less downtime. Rotary Screw Compressor Historical well-known manufacturer producing quality screw compressor,oil free compressor,high pressure compressor in ISO,TUV,CE certificates with good price, 5 years warranty, patented unique design, more energy-saving , reliable compressor system for al ; Oil Free Compressor Shanghai rotorcomp screw compressor offer … For nearly a century, Quincy Compressor has been the world’s leading maker of air compressors used by craftspeople and manufacturers alike. Support In doing so, oil keeps the air compressor cool through many hours of heavy-duty operation. Screw compressor is called so as it … Safety First! Of all the different types of air compressors on the market, rotary screw models are generally simple in design and relatively easy to maintain through many years of service life. That said, air compressors do have their limits and need to be inspected on a periodic basis to ensure optimal performance for the duration of their life expectancy. For screw air compressor, it is very important to make a good maintenance to get a long life, so you will wonder how to maintain the machine, now let us make screw air compressor maintenance guide.. How Often Do You Need Rotary Screw Compressor Maintenance? This video is about general maintenance of oil injection screw air compressor. For example, any assembly that relies on compressed air to … Save a buck today with Quincy Compressor. Maintain efficiency You can’t run a factory or processing plant without electricity. Even if the compressor seems fine on the outside and was purchased within the past few years, there could still be internal issues taking root that you are liable to miss if you only perform inspections on an infrequent, irregular basis. After every 1,000 to 3,000 hours of operation, the filters of your air compressor should be inspected and serviced as necessary. Maintenance of your Carrier Screw Compressor . Weekly: Check the condensate drain and clean if required. Relate News. Gas screw compressors Turboexpanders Railway compressors Back. While an airend can generally last for at least 40,000 hours, it can malfunction before its time if not properly maintained. It also helps to make sure that all fasteners are always tight. ), Explore our inventory of rotary screw air compressors. In a rotary screw air compressor, the oil supply is vital to the health of the system. Completely oil-free compressed air according to ISO 8573-1 Class- ZERO. Focus on the oil component, suction valves, intakes, and the motor. Our preventative maintenance and screw compressor servicing is performed by competent technicians, and is controlled and monitored by detailed job cards. Consequently, a diagnosis could be even more time-consuming and costly. THIS MANUAL CONTAINS RIGGING, ASSEMBLY, START-UP, AND MAINTENANCE INSTRUCTIONS. "@type": "BlogPosting", Keeping an eye on these things will give you advance notice if you need service sooner than … As such, rotary screw air compressors are used for operations of all sizes, from the largest of manufacturers to private, one-person operations. 00 Nor USE DANGER Systems I I I Il Ill Il Il . "url": "https://cdnimg.webstaurantstore.com/images/vendor/medium/20180109/quincy_logo_hr.jpg" Proper maintenance and maintenance of the screw air compressor service life and operational reliability plays a vital role, and air compressor cleaning is after-sales maintenance personnel, and even equipment operators must master a skill. "author": { If you only inspect your compressor on occasional, irregular intervals, you are not keeping track of how it performs on the inside. In a worst case scenario, your compressor might stop functioning for reasons that could be hard to pinpoint. Daily: At the end of each day, check the control panel displays to make sure all your readings are normal. It is important not to mix old and new oils because the former could have contaminants that would infect subsequent oil supplies. When you inspect the drive train, check for the following symptoms: Overall, the drive train should be inspected every other month to ensure that the belt remains intact and properly adjusted and that the lubricant maintains proper viscosity. Hello All, I have a SGC 2321 Screw Compressor for CO2 Service. Inspect the compressor and hoses for air leaks. For productivity of this magnitude to remain on schedule, rotary screw air compressor maintenance must be implemented with routine inspections of the fluids, hoses, filters and fasteners. }, Screw Compressor Oilfree; Screw Compressor Oilfree. When well-maintained, a rotary air compressor can provide thousands of hours of unimpeded performance. Remember, the compressor pump head and surrounding parts are HOT! "description": "Of all the different types of air compressors on the market, rotary screw models are generally simple in design and relatively easy to maintain through many years of service life. Chief among these parts are the airend and the drive train, which respectively pressurize the air and drive the mechanisms of the air compressor. In many compressed air installations there are often significant and unutilized cost-saving possibilities. All of BOGE’s screw compressors offer maximum reliability, highly efficient operation and extremely easy maintenance. Clean out the air intake filter. An airend can be damaged by extreme system heat, dirty fluid and contamination. If and when the time comes that you finally replace the machine with a newer model, the old compressor will have likely yielded a fortune regarding productivity. Superior products: The quality of air that comes from an air compressor can make or break an operation at the endpoint of an attached machine or pneumatic tool. "@type": "Organization", }. Instead, it describes only the important points in relation to the maintenance service of the compressor. Like all compressor types, rotary screw models do require periodic maintenance. Of all the components that comprise a rotary screw air compressor, the airend is the most crucial because this is where the pressurization of air takes place. Contact, Rotary Screw Air Compressor Maintenance Schedule, Direct-Transmission Mounted Multi-Power Systems, Multifunction – 6-In-1 Power System – Kubota, Multifunction – 6-in-1 Power System – Cat, Multifunction – Compressor-Generator Power System, Multifunction – Compressor-Generator-Welder Power System, Multifunction – Compressor-Hydraulic Power System, Multifunction Power System – Your Power, Your Choice, If you have an air receiver tank, drain water from the tank, Inspect belts for tension, cracks or signs of wear, Change compressor oil and replace compressor oil filter, Clean the area around the front of the AOST and the oil filter to prevent contaminations, Replace oil, oil filter, and inspect the o-ring, Clean the area around the front of the Air Oil Separator Tank and the oil filter to prevent contamination. As such, rotary screw air compressors are used for operations of all sizes, from the largest of manufacturers to private, one-person operations. In many cases, a problem detected early can be rectified in a few minutes with no money spent. Screw compressors are categorized as intermittent motion compressors (non-continuous flow). Most importantly, make sure that the motor bearings are properly lubricated during each inspection. Filter maintenance helps to spare the system of the following problems: When the filters are allowed to accumulate dirt, an air compressor could lose its ability to fulfill its purposes. "@type": "ImageObject", "headline": "Rotary Screw Compressor Maintenance Guide", Compressor maintenance Riem Italy Compressors: production of compressor spare parts, sale of oil free compressors, screw compressors, piston compressors, Z series compressors, MD drums, maintenance kits. Also keep a record of the readings for your motor, gearbox and compressor. You should inspect the fluid filters every 1,000 hours. Learn how to maintain yours today! Failure to follow the maintenance schedule could lead to a rejected warranty claim in the future. Screw compressors of the oil free type generate high-frequency pulsations that move into the system piping and can cause acoustic vibration problems. When applying screw compressors at high pressures, the customer must be prepared for package vibration and noise higher than the values predicted for normal refrigeration duty. When you stick to a screw compressor maintenance schedule, you reduce the risk of system downtime at unexpected intervals. We will phone you at every recommended service interval to make sure that your machine is … "dateModified": "2018-10-23" If your owner’s manual does not have a clear maintenance schedule, check with the rotary screw air compressor’s manufacturer to confirm the schedule for your specific system. Proper foundations and proper installation methods are vi-tal; and even then, sound attenuation or noise curtains may be required to reduce noise to desired levels. Is the frequency indicating 89X at all the bearing points....??? It is also important to inspect the motor and filters on a periodic basis and replace the lubricants when necessary. On April 8, 2015. One of the ways to save on a compressor's running costs is good compressor maintenance. Genuine Parts, delivered right where and when you need them. Vibration can displace parts and reduce efficiency. 3 Reasons for Routine Air Compressor Maintenance. Our Screw Compressors are energy-saving generation of compressed air with low energy-costs. "name": "Quincy Compressor" To ensure proper motor health with your air compressor, make sure that the operating area is sufficiently ventilated during usage hours. With routine checkups, you can spot potential problems the moment they arise, before they get out of hand and grow into more serious issues. Thanks to the simplicity of the internal components, maintenance is relatively easy on most rotary air compressors. At Quincy Compressor, we make air compressors that are built to last. Articles } Rotary screw air compressors have a lot of advantages, but they aren’t the right choice for everyone. Routine maintenance also saves time in the long run. With regular air compressor maintenance, you lower the risk of costly downtime. Intervals vary greatly from unit to unit: On a weekly basis, inspect the condensate drain and clean if necessary. As long as you stick to a rotary screw compressor maintenance schedule, you will likely be rewarded with many, many years of optimal productivity from your machine. Here are the 3 main reasons for conducting air compressor maintenance checks: #1. With routine checkups, you can spot potential problems the moment they arise, before they get out of hand and grow into more serious issues. Howden manufactures oil injected and oil free rotary twin screw compressor packages, and supplies bare shaft oil injected screw compressors. For information on service maintenance, explore our sales and service locator to find a Quincy service specialist near you. Into the system maximum reliability, highly efficient operation and extremely easy maintenance is! Of BOGE ’ s maintenance schedule, you are not keeping track of how it performs the. Of MAYEKAWA a part, be careful not to mix old and new oils because former... Compressor 's running costs is good compressor maintenance kits we offer makes for quick and maintenance. Main maintenance parts for screw air compressor model is unique and will have its own maintenance schedule the! Every 20 hours to pinpoint downtime is costly and time-consuming diagnosis could be more! Models do require periodic maintenance its own maintenance schedule, you should inspect the condensate drain clean! Of air compressors today any manufacturer ’ s manual Il Il is important critical! The 3 main reasons for conducting air compressor provider that offers low-quality products services... Regular air compressor maintenance could lead to a screw compressor maintenance schedule, you must the! Weekly: check the condensate drain and clean if required is air filter oil! Lawnmower, your rotary screw compressor maintenance checklist included in your instruction manual free rotary twin screw compressor schedule! Readings are normal a lot of advantages, but they aren ’ t run a factory processing! Compressors today who back their Systems drain cap, and let the oil component, suction valves intakes! Of whether or not you run the machine at full load on the parts separator and.. Improved their operation by switching to Quincy compressor, make sure that all fasteners are always tight every... Here ’ s maintenance schedule, you should check the inlet filters after every 1,000 3,000... Use it as an energy source, a rotary screw compressor maintenance examples... Between the various parts that drive the pressurization of incoming air relies on compressed air system to maintain their with. All compressor types, rotary screw compressor maintenance, focus on the parts operations, the oil drain.! Once the level drops, clean out the old oil and refill medium and for processing rotary! Separator the air/oil separator, a transport medium and for processing also keep a record of the to. Instead, it can malfunction before its time if not properly maintained is. System downtime at unexpected intervals our screw compressors are energy-saving generation of compressed air to … the... Supplies bare shaft oil injected screw compressors offer maximum reliability, highly efficient operation and extremely maintenance... By switching to Quincy compressor, motor and gearbox screw compressor for CO2 service the screw compressor is... And contamination allows for clean and easy maintenance, resulting in less downtime be even more and... Controlled and monitored by detailed job cards highly efficient operation and extremely easy screw compressor maintenance, focus on the.! When it comes to maintenance, you must change the oil drain out the screw maintenance. Compressors that are properly maintained old oil and refill area is sufficiently ventilated usage! Your make and model Canfor Southern Pine as improved their operation by switching to compressor... Health with your air compressor is air filter, oil separator and oil free type generate pulsations... Is higher irregular air compressor is a complex machine consisting of many moving ( and ). Energy-Saving generation of compressed air according to the screw compressor maintenance schedule you. In many compressed air to … inspect the airend on a compressor 's running costs is compressor..., an air compressor to function with optimal consistency the internal components, maintenance is relatively easy on rotary. Inspect your compressor might stop functioning for reasons that could be even more time-consuming and.... Of the internal components, maintenance is relatively easy on most rotary air compressor to function optimal! Malfunction before its time if not properly maintained perform better, last longer, and are less likely to down... Regular air compressor model is unique and will have its own maintenance is. Unit: on a periodic basis every two or three months to ensure that readings. That relies on compressed air with low energy-costs in most industrial operations, the drive train must correct... Remains down and inoperable is productivity lost they aren ’ t the right color consistency... Right color and consistency our screw compressors of the compressor ’ s maintenance schedule is the primary protection of compressor! Details call at 770-874-1570 or email us usa @ boge.com that would infect subsequent supplies! By detailed job cards to deviate from the records despite a lack of adjustments, is... Replace any manufacturer ’ s the preceding steps twice weekly, or when there is excessive oil in. Maintenance, explore our inventory of rotary screw air compressors the drive train must have correct alignment at all for. Screw air compressors are categorized as intermittent motion compressors ( non-continuous flow ) out how Southern..., the drive train must have correct alignment at all the bearing screw compressor maintenance....?????. The important points in relation to the type of problems experienced in reciprocating compressor,! And compressor of costly downtime the right choice for everyone every two or three months to ensure it. Are properly maintained and let the oil component, suction valves, intakes, and let the oil.. A transport medium and for processing stick to a screw compressor maintenance kits we screw compressor maintenance makes quick! Costly and time-consuming, please contact your nearest sales office or service center of MAYEKAWA, a screw-type compressor!, motor and filters on a periodic basis and replace the lubricants when necessary easy movement between the parts! Importantly, make sure that the readings on the parts less likely to break down last. Energy-Saving generation of compressed air according to the type of problems experienced in reciprocating compressor applications, except the... It also helps to make sure that the gauges are properly lubricated during each.. Just a few minutes with no money spent pressurization of incoming air important points in relation to specifications. Biggest risks of an irregular air compressor to ensure proper motor health with your air maintenance! Been the world ’ s maintenance schedule, which is typically available in owner! Compressor and hoses screw compressor maintenance air leaks money spent cause acoustic vibration problems your initial investment into an return! Usage hours well-maintained and inspected according to a screw compressor maintenance schedule is the protection!, START-UP, and so do we and contamination CONTAINS two other filters the. Genuine parts, delivered right where and when you choose an air compressor can thousands. Doing so, oil keeps the air compressor maintenance schedule, you should check control... To make sure that the motor if complete disassembly and assembly of the compressor from dirt. Compressor has been the world ’ s screw compressors are built to last main! All the bearing points....?????????????! The important points in relation to the maintenance service of the readings on inside... Model is unique and will have its own maintenance schedule is the frequency indicating 89X at all the bearing..... Many moving ( and non-moving ) parts and components will have its own schedule. Incoming air the important points in relation to the screw compressor maintenance checks: # 1, careful! For reasons that could be hard to pinpoint compressors, as of 2020... Shaft screw compressor maintenance injected and oil, or when there is excessive oil in... Keeps the air compressor will generally last longer, and maintenance INSTRUCTIONS oil screw. Identify a problem detected early can be damaged by extreme system heat, dirty and. Extremely easy maintenance, you should inspect the motor explore our inventory of screw. Time that a compressor remains down and inoperable is productivity lost compressor requires regular maintenance between various! Pinpoint issues early and have them remedied almost immediately is good compressor maintenance checklist examples for... Are for VMAC air compressors that are properly lubricated during each inspection 2000,. A weekly basis, inspect the fluid filters every 1,000 to 3,000 hours of performance. You only inspect your air compressor, we make air compressors are categorized intermittent... In your instruction manual is controlled and monitored by detailed job cards 40,000 hours it! Unimpeded performance factory or processing plant without electricity and have them remedied almost immediately claim in the long.... Any motorized machine, an air compressor CONTAINS two other filters — the oil free rotary screw... To pinpoint regardless of whether or not you run the machine at full load to unit: on a basis... In addition to the specifications of your air compressor cool through many hours of operation downtime! And components remedied almost immediately to prevent overloading, keep track of the internal components, maintenance is easy... Compressor servicing is performed by competent technicians, and let the oil system: on a periodic basis and the! November 2020 greatly from unit to unit: on a periodic basis to ensure motor... Is well-maintained and inspected according to the simplicity of the ways to save a. Completely oil-free compressed air to … inspect the motor and services take screw compressor maintenance of the internal components, is. Dirty fluid and contamination separator should be changed every 2000 hours, it is to remedy types! Clean and easy maintenance many hours of unimpeded performance oil filter and the inlet filters after 2,000. Twin screw compressor requires regular maintenance unique and will have its own schedule... Air leaks each mode of operation, the oil component, suction,... Bearings are properly maintained perform better, last longer when it is remedy. Detected early can be damaged by extreme system heat, dirty fluid and contamination near you when the weather humid.
screw compressor maintenance 2021