Building the Future

Steel is one of the world’s most essential materials in engineering and construction. Steel components are utilised in almost everything- from vehicles to domestic appliances to surgical scalpels! 

The vast applications of the metal are attributed to its durability and flexibility. The World Steel Association forecasted that steel demand will increase by 2.2% in 2023 to reach 1,881.4 million tonnes (MT).  

India is currently the world’s 2nd largest producer of crude steel in January – December 2021, producing 118.20 Million tonnes (MT) crude steel with growth rate 17.9% over the corresponding period last year (CPLY). Source 

A leading steel manufacturer  

Our customer is a leading steel manufacturer, which began operations in 1998. Ranked as one of the top in India, the organization is also recognized as the second largest value creator in the world.  

The diversified portfolio of steel products comprises steel plates and coils, angles and channels, wire rods, round bars, rails, parallel flange beams, and fabricated sections. The product line is in high demand across 22+ countries owing to its durability and quality. 

From Scrap to Steel 

Steel is a sturdy iron alloy with chromium, manganese, and nickel elements. Our customer’s production process typically involves these steps:  

•   Raw material sourcing: Iron ore, coal, and lime are the primary raw materials used to produce steel. The company owns coal and iron-ore mines to source the raw materials. 

•   Sinter plant: The raw material is subjected to an agglomeration process in the sinter plant. The fine mineral particles are combusted into a porous mass known as sinter. 

•   Blast furnace: The sinter contains 70% to 80% of the iron. The charge is transferred from the sinter plant to the blast furnace, which is melted to produce hot metal or liquid iron.

•   SMS: Refractory lined vessels called LD Converters are used to produce steel from the liquid iron. Impurities such as carbon, silicon, phosphorus, and sulphur are removed by blowing oxygen through a hot metal bath. The molten steel is continuously cast at the radial type continuous casting machines.

•   The finished product: Steel is moulded into slab, strip, billet, bloom, and beam blanket as the final product. These are descaled, tested for quality, sorted by weight, and stored for shipment.

Chinks in the Armour 

Steel manufacturing plants need high-pressure and high-quality air to descale the final products. The hydro-mechanical descaling process eliminates impurities from the product. Special descaling nozzles form jets arranged on spray headers in the steel mill. The finished products are then subject to a working pressure ranging from 80 to 300 bar for descaling application. 

The process involves converting sheets into heat-rolled slabs. Iron oxide or mill scale is deposited on the sheets and must be removed repeatedly to clean them. The challenge was deploying an air system that could descale the sheets properly. The highest quality of high-pressure compressed air was required to ensure the best surface finish was achieved, as it directly impacts the product quality.  

Making Things Right  

Our customer switched to an ELGi Sauer high-pressure air compressor in 2017.  

A unit of the Hurricane Series Model WP4341L was installed for the descaling application process at the rolling mill. The Hurricane Series high-pressure compressors are renowned for engineering superiority and production expertise. Founded on outstanding military design experience and continuous innovation, this is one of the most cost-effective and reliable air-cooled industrial compressors in the market ranging from 115 to 400 bar. 

The installation of the ELGi Sauer air compressor came with so many benefits:  

•   Descaling the final product:  Descaling to deliver high-quality finished products with maximum shine.

•   Heavy duty performance:  Delivering performance even under extreme environmental conditions.

•   Minimal downtime: The reliable compressor performance, low downtime, and swift maintenance by the ELGi Sauer service team ensured high availability of the compressor to deliver high-quality products consistently. 

“ELGi Sauer’s high-pressure compressor satisfies our needs and helps us deliver high-quality products consistently. It is durable and reliable, and we are happy with its performance. It is easy to operate, and we can use this machine for our heavy-duty applications with full confidence. Partnering with ELGi Sauer was the best decision for our business.”  

Our customer feedback  

The trouble-free performance, ease of maintenance of the compressor package and lower operating cost has won the user’s confidence. Repeat orders in 2019 reflected customer satisfaction. To provide the complete trouble-free availability of the compressor considering criticality in the plant, ELGi Sauer has taken the compressors under maintenance ensuring they are attended to by qualified service engineers conforming to prompt and timely periodic service ensuring superior performance.  

“At ELGi Sauer, we understand the customer and application needs very well and consistently deliver the best-performing and most suitable equipment. Our products are built with reliability and lower life cycle cost, making them the most preferred choice of the customers. With prompt product support through service contracts, we keep our customers stress-free, enabling them to focus on enhancing their business growth,” said  Satish Kini, Chief Executive Officer of ELGi Sauer Compressors Limited.   

Technology and innovation in focus for ELGi Sauer  

The latest in-built technology with ELGi Sauer compressors makes them future-ready and the most preferred by customers. Advanced control systems, compressed-air treatment systems, and accessories are available to meet the customer’s specific needs. 

ELGi Sauer has significantly expanded its business portfolio in the past decade and has become the most preferred choice across major industry segments in India. Delivering state-of-the-art products and customized solutions to steel, auto, power, general engineering and oil & gas segments, ELGi Sauer helps its customers achieve high productivity at low maintenance cost.   

Speak to our experts for customised solutions for your industry applications. Share your requirement here.

Sources:

World-Steel-in-Figures-2022.pdf (worldsteel.org) 

Factors affecting energy consumption:  Following are the major factors affecting the energy consumption of a compressor 

       1. Selection and sizing of compressor 

       2. Selection of air accessories 

       3. Piping layout 

       4. Operating pressure 

       5. Delayed maintenance 

       6. Artificial demand 

       7. Leakage 

       8. Managing multiple compressors operation 

       9. Heat of compression 

Now let’s discuss the above factors in detail.                                                                                                   

Selection and sizing of compressor: It is very critical to select the right type and right capacity of the compressor during the initial plant setup. For example, selecting a lubricated compressor and installing downstream filters to remove the oil particles instead of selecting an oil-free compressor will result in energy loss due to pressure drop across the downstream filters which can be avoided. Similarly, oversized (higher capacity) compressors will run in unloading conditions for longer durations and will waste energy.     

Selection of air accessories: The selection of the right accessories for the air compressor plant plays a vital role in reducing the energy of the compressed air system. The size and type of downstream filters, dryers and receivers if not carefully selected, will lead to excessive power consumption and hamper the production process. 

Lower sizing of downstream filters à Excessive pressure drop and power consumption 

Lower sizing of refrigerant dryers à Excessive moisture carryover, disturb the production process and may damage the user end equipment and machinery 

Higher sizing of desiccant dryers  à Excessive purge loss and power consumption 

Undersized storage receivers à Increased energy cost on load/unload compressors.

Piping layout: The design of the piping layout has a long-time effect on the compressed air system. Inefficient design of the piping layout will lead to excessive pressure drop, and increased leakage and in turn will result in the energy cost of the compressed air system shooting up over the period. It will be advisable to consider the below factors while designing the compressed air piping layout. 

• Piping material (Aluminium or plastic instead of MS/GI pipes) 
• Piping layout (looped or non-looped) 
• No. of joints, bends, elbows, and Tees 
• Welded or o’ring joints instead of threaded joints 

• Diameter of the main header/sub headers 

Operating pressure: Operating the compressor at higher pressure than the pressure required for the end user, will increase the energy bill of the compressor substantially. As a thumb rule, in the systems operating at 7 bar pressure, every one bar increase in the operating pressure will increase the energy consumption by 7%. It will be prudent to set the compressor load and unload pressures considering the requirement of the end user and the estimated pressure drop between the compressor and the pressure required at the farthest point of the application.  

Delayed maintenance: Timely maintenance of the compressor and replacement of consumables and other maintenance kits as per the recommended maintenance schedule of the OEM will go a long way in ensuring the trouble-free operation and efficient performance of the compressor. Delaying the maintenance of the compressor and not replacing the consumables like an air filter, oil filter, air/oil separator element and the coolant/lubricant on time will increase pressure drop across these filters and in turn, increase the energy consumption and reduce the capacity of the compressor. 

The table below shows the impact of the delay in the replacement of the consumables for a 75 KW compressor. 

Artificial Demand: It is the increased compressed air consumption of the system due to operating at higher than necessary operating pressure. Unregulated compressed air use, leakage, blowing applications, tools, air motors, pneumatic cylinders etc. all consume more compressed airflow as system pressure increases. Air demand increases by 2 % for each 2 psi increase in operating pressure. Artificial demand can be reduced by reducing the operating pressure and by setting the compressor load/unload pressures at the optimum range. 

Leakage: Leaks in a compressed air system can waste your operating budget on high electricity consumption every year. In many manufacturing and processing plants, the leakage can account for up to 20% of the total energy cost of the compressor. The most common areas where you might find leaks are connection joints like valves, unions, couplings, fittings, etc. This can also cause the compressed air system to lose pressure which reduces the efficiency of the pneumatic tools or machines that make use of compressed air in the system like an air-operated actuator being unable to close a valve, for instance, and may cause rejections in the end product. 

One simple way to estimate how much leakage a system has is to turn off all of the point-of-use devices / pneumatic tools, then start the compressor and record the average time it takes for the compressor to cycle on and off. The total percentage of leakage is calculated as follows:  

% Percentage = [(T x 100) / (T + t)] where T = on time in minutes, t = off time in minutes 

The percentage of the compressor’s capacity that is lost should be under 10% for a system that is properly maintained.  

Multiple Compressors Operation: An unmanaged control scheme for a bank of air compressors is a recipe for unnecessary consumption of power, as well as increased or unplanned maintenance and can cause one or more of the following problems: 

• Too many compressors are running. 
• The wrong combination of compressors is running. 

• Pressure is higher than it needs to be. 

When a rotary screw compressor is running unloaded, it will still consume about 30% of its full load power, but since it is producing no air, this wastes power if the run time is unnecessary. 

For systems with more than three compressors, it is usually necessary to implement some sort of automatic control using a compressor controller. This is because the higher the number of compressors, the wider the total system pressure band will be, eventually exceeding the compressor pressure ratings. 

Typical controllers communicate with all the system compressors and choose the best compressors to run at any one time, depending on a control algorithm and operator input. Most often, the controller will run the compressors in a single pressure band arrangement that will keep the pressure within a narrower and lower band. Most controllers will incorporate any variable speed compressors. 

Running with lower pressure reduces the average compressor power consumption. Running only one trim compressor minimizes wasteful unloaded run time. With any system, an adequate amount of storage receiver capacity needs to be installed—the typical size required is between 2 to 4 cubic metres per 100 cfm rating of the largest trim compressor. 

Many modern compressors already have sequencing control built into the onboard controls; if your system is newer, you should look into this possibility. If you are concerned about your compressor control and would like to improve it, contact your compressor service provider to come to have a look at your system. Your supplier may have a control system solution to help solve your problems. 

Heat Recovery Systems: It is a surprising fact that 100% of the electrical power (energy) is converted to heat energy during the compression process in an air compressor and all the heat energy goes waste if not used judicially.  

In a typical compression system, the theoretical recoverable heat is 96% of the overall electrical energy consumption. It consists of heat dissipated in the oil cooler (78%) the aftercooler (13%) and the heat radiated from the drive motor (5%). The rest 4% of heat cannot be recovered since 2% radiates through the canopy and the other 2% vents inside the canopy. 

Keeping in mind the effects of global warming in the present environment, it is recommended that using a heat recovery system 76% of the waste heat generated from the compressor can be utilized for heating air (space) and heating water. This in turn eliminates the necessity to go for additional equipment to heat water or air, thereby reducing the CO2 emission to a larger extent. 

Schematic Diagram of Heat Recovery Unit 

With increasing energy costs, the performance and efficiency of your compressed air systems have never been more important. ELGi’s Air audit may help users identify potential opportunities for energy savings in their compressed air system and thereby reduce the total operational cost. Our Audit Report includes identifying all the big, medium, and small opportunities for energy savings in the compressed air system and providing recommendations on short, medium, and long-term measures for energy conservation, along with financial estimates and analysis for their implementation. The audit involves a wide range of sophisticated, portable diagnostic and measuring instruments to generate refined data and facilitate complex analysis to give a more reliable basis for identifying energy-saving opportunities, evaluating performance, energy-saving measures, and economic viability. In addition, ELGi’s Air audit will benefit customers by reducing the wear, tear, and maintenance costs during the lifetime of the entire compressed air system.  

In most places, water is dug out of the earth for drinking. In the olden days, wells used to be dug, but as the water table receded, depths increased, and today water wells of 4.5”-4.75”, and 6” – 6.5” are very common. Tube wells have become the order of the day to access potable water from the earth’s crust.   

A brief overview of water well drilling applications. 

Water well drilling equipment consists of a water well rig, air compressors & accessories like drilling rods, casing pipes, and a hammer. In most cases, for deeper water well drilling, DTH drilling is adopted. DTH Drilling is an efficient way of drilling for deeper holes in medium or hard formations as hammering action is provided right on the drill bit at the bottom of the hole.  

To fulfill the requirements of water well drilling applications, ELGi manufactures efficient and rugged compressors. 

Here is look at the typical mounting of the equipment in water well drilling application: 

Both Compressor and Rig in the same truck. 
 

The process of drilling 

Typically, a water well drill consists of the following activities:  

 – A large hole is drilled to insert casing pipe (anywhere between 20-200 ft) using the Over Burden hammer 

– Which removes the top layer of the earth’s crust to prevent any collapsing materials into the well.  

– Then, a hole of the actual size is drilled. 

 Today in India, the average depth ranges from 800-1200 ft depending on the water table in the zone under consideration.   

Different stages of Drilling 

For water well compressors, there are 2 very important aspects in any compressors. 

Drilling state: In this phase, compressed air is needed at the required pressure for efficient hammer performance. The drilling state forms 75-80% of the overall drilling cycle. Compressor performance is critical in ensuring profits for the Drill rig owner.  

 ELGi compressors deliver the required amount of compressed air to ensure optimum drilling.  

 Flushing State: This phase requires the maximum flow of compressed air to remove the cuttings/debris from the hole. This state plays a critical role in determining the fuel consumption of the compressor overall, as generally, the compressor consumes more fuel if flushing is too much. Typically, flushing ranges from 10-15 % of the overall drilling cycle.  

 Another state is idling where the compressor delivers no air, however, it remains in that state, as the rig will undergo rod change activity.  

A water well depth depends on water yield or until a customer wants to try for water. Finding a drilling point is a different topic for discussion as there are multiple ways, be it using a scientific method of using a geologist or a traditional method like using a water diviner.

Unlike rotary compressors that are designed to run continuously without wear or damage due to overheating, piston compressors cannot run continuously for extended periods as their design has a lot of moving parts, and the cooling and lubrication system is basic. Piston compressors thus have a specified percentage of time they can run without causing any sort of damage to the compressor.  

What Is an Air Compressor Duty Cycle? 

To understand the air compressor duty cycle it is important to first know what cycle time means. When it comes to piston compressors – they run on a start/ stop cycle; meaning when the desired maximum pressure is reached the compressor stops and starts back only when it reaches a set minimum level. The time between one stop and start is the total cycle time. 

The duty cycle is generally represented as a percentage. It is the time duration a compressors’s top block runs to provide pressurized air at a defined flow rate relative to the compressor’s cycle time.  

Why Is Duty Cycle Important? 

The duty cycle is important as it helps to understand how efficiently a piston compressor functions by stopping and starting during use. It helps to determine if a given compressor model will fulfil the air needs of the application when sizing the compressor system. 

It is also important for ensuring the optimum life of the compressor, as exceeding the recommended duty cycle can prematurely wear out or damage the internal components.  

Duty Cycle Deciphered  

If a piston compressor’s cycle time is 10 minutes, and it runs for 7 minutes during that time, then it runs on a 70% duty cycle, which means 3 out of 10 minutes the compressor will be resting/cooling down during a cycle.  

A piston compressor that specifies a 100% duty cycle does not mean it can run continuously, but it can provide air at a specific pressure and flow for the time it runs (In the above– said case it is 7 minutes) with the help of a storage tank. 

Why should Duty Cycle be optimum?  

Heat is generated due to friction while the compressor is operating. Primary source, which is the friction between millions of air molecules while getting compressed makes compressed air very hot. The secondary source of friction are the moving parts inside the compressing unit, which raises the temperature of the cylinder as high as 150 to 200 Deg c.  

99% of the industrial piston compressors come with a basic splash lubrication system –here the oil properties play a vital role in ensuring proper lubrication. Excess heat generation deteriorates the oil properties thereby impacting the lubrication.  

The cooling system is not as sophisticated as what is available in other types of compressors. In a piston compressor, the cooling is majorly forced air cooled with fabricated or casted fan pulleys mounted on the compressor shaft and Copper or Aluminium pipes acting as coolers. These require non-operational time to ensure sufficient cooling time and avoid further heat generation between cycles. 

Effects of running at 100% Duty Cycle 

Some of the effects of running a piston compressor at 100% duty cycle are 

• Piston seizure in the piston housing due to excessive heat in the cylinder 

• Vales expand and jam with continuous exposure to a higher temperature, causing catastrophic failure of the compressor 
• Changes in oil properties lead to higher oil carryover 
• Continuous exposure to higher temperatures leads to higher condensate formation in the receiver tank thereby increasing moisture carryover to the downstream equipment and to the end equipment 
• Higher maintenance cost due to quicker wear and tear of internal parts 

Recommended Duty Cycle 

It is critical to know that the 100% duty cycle on a piston compressor does not mean that it can run continuously. Doing so can damage the compressor, resulting in premature wear and higher maintenance costs.  

Different brands recommend different duty cycles based on their design standards. The ideal duty cycle recommended for piston compressors by ELGi is a 70:30 duty cycle.  

Always choose a compressor that best suits the application requirement!  

Energy costs account for approx. 30% of a production facility’s operating budget. That means nearly a third of all the money organizations invest into their plant, goes straight to the power bill. Power cost is a pivotal determinant of the overall cost to companies. 

Globally, business owners have embraced sustainable techniques to ensure   convenience, and efficiency in their facility, but is it possible to go too green? Absolutely. 

Considering the implications of global warming, ELGi introduced a Heat Recovery System, which enables the reuse of heat energy generated during the compression process for tasks like heating water. 

Refine Your Compressed Air System with ELGi’s Heat Recovery System 

ELGi’s Heat Recovery System can assist in using 78% of the waste heat generated by the compressor for other facility operations, such as heating water. As a result, there is no longer a need to purchase additional equipment to heat water, thus lowering CO2 emissions. The Heat Recovery System is an accessory which can be used with the ELGi EG Series rotary air compressor. Customers can easily plug the HRS into an air compressor to warm water and air for use in showers and boilers by using the heat produced by the air compressor.  

In a typical compression system, the theoretical recoverable heat is 96% of the overall electrical energy consumption. It consists of heat dissipated in the oil cooler (78%), the after cooler (13%) and the heat radiated from the drive motor (5%). The heat dissipated by the oil cooler can be used for heating water and the heat dissipated by the after cooler and drive motor can be used for supplemental space heating. The remaining 4% heat cannot be recovered, since 2% radiates through the canopy and the other 2% vents inside the canopy. 

Robust Operations Across Industries 

The Heat Recovery System finds its operation in industries like automotive, textiles, cement, paper & pulp, machine tool shops, steel making and the food processing industry where there is a need to heat / pre-heat water to a certain temperature ELGi’s HRS can significantly reduce energy costs by eliminating the use of special heating equipment or by offering the initial heat to start the heating process where higher temperatures are required. 

Elgi is a global air compressor manufacturer with an expansive line of innovative and technologically superior compressed air systems. ELGi has consistently ensured that its customers achieve their productivity goals while keeping the environmental impact low. Our product innovation for the Heat Recovery System is driven by the potential for savings and by examining the carbon footprint of an air compressor. ELGi firmly believes that sustainable technology is at the heart of positive environmental change.    

Explore our portfolio of sustainable & efficient solutions here: http://www.elgi.com 

Paul Edward Theroux, the famous American novelist, and traveller, once said: “The railway possessed India and made her hugeness graspable.” The Indian Railways is the world’s largest passenger carrier and the fourth-largest freight carrier (1). It is the fourth-largest railway network globally-only behind the US, Russia, and China. (2) Its immensity can be gauged from the fact that the 95,981-kilometre route length of the Indian Railways carried 8.4 billion passengers and $1.2 billion worth of freight during 2018-2019. More than 12,000 passenger trains run across the country daily and cumulatively cover a distance more than four times the earth and the moon. (3)

The Indian Railways began its journey in 1832 and has grown to become the giant it is today. As one of the primary drivers of India’s economic growth, the Indian Railways has achieved this by being financially viable, technologically brilliant, and environment friendly.

The Indian Railways has also defied the trend that many big companies face.. On the contrary,  they have cruised along and undertaken numerous initiatives to upgrade their infrastructure and quality of service.. 

These efforts have resulted in the Indian Railways achieving double-digit growth in freight traffic and doubling its freight speed on the back of massive infrastructural upgrades. Besides, new initiatives are always at play, from train control, signalling, and electrification to expansion through modern locomotives and EMUs, to name a few. 

More importantly, the Indian Railways has its goals set with social and financial objectives in mind-from efficient energy use to the new decarbonisation paradigm and aiming to become a net-zero carbon-emitter by 2030. (7)

While all this is no mean feat as the world continues to struggle with partial lockdowns, there is a lot more to come, with India projected to account for 40% of the global share of rail activity by 2050. (4) The target is achievable since the government plans to invest ₹50000 billion in railway infrastructure by 2030. (5) It has also identified many new high-speed rail corridors besides planning INR 3 trillion worth of metro rail projects across various cities over the next five years. (6)

Addressing Challenges

For the Indian Railways, maintaining the highest standards of compressed air holds critical importance. Without it, machines unexpectedly break down, demand expensive repairs, or cause uncomfortable turbulence. For rolling stock of all capacities-from locomotives to good wagons to passenger coaches, whether powered by electricity or diesel – the railways need high-quality compressed air for smooth and safe operations. Moreover, various train components, whether the braking system, doors, pantograph devices, or air suspension, rely on high-quality compressed air solutions for safety and overall reliability. The Indian Railways is also subject to a variety of constantly changing compliances and regulations.

In the 1960s, the Indian Railways took many progressive steps towards modernization and adopted 25kv AC traction for electrification. (8) While the Indian Railways urgently required compressors to modernize the braking system, it could not directly import foreign solutions because the country was hit by twin mass famines (9), and liquidity was in short supply. Besides, though the second five-year plan (1956-61) initiated industrial import policies, there was not much clarity around it. (10) However, the government was proactively piloting several initiatives to trigger domestic economic growth. It encouraged the Indian Railways to initiate production work for electric locomotives at Chittaranjan Locomotive Works and flagged off the first 1500V DC electric locomotive from Bombay in 1961. (11)

By the early 1960s, ELGi began assembling and manufacturing small compressors under the brand name ELGi Uraca. It imported only major components and either manufactured the rest in-house or procured them locally. With urgent requirements arising from the Indian Railways, and a mandate to keep costs low, ELGi opened an indigenous compressor manufacturing unit in the heart of Coimbatore. The first product supplied to the Indian Railways was a 1000 litres per minute capacity compressor driven by a battery-operated direct current (DC) motor. 

Since then, ELGi has consistently delivered a wide range of sustainable and efficient compressed air solutions to the Indian Railways. Today, 90% of Indian Railway’s electric locomotives, 65% diesel locomotives, and 60% electric multiple units (EMUs) use ELGi air compressors for braking applications and auxiliary systems. 

“The Indian Railways has been ELGi’s important customer for over five decades. Increasing urbanization and rising incomes have contributed to significant growth in the passenger segment, while freight traffic also saw a marked increase due to dedicated freight corridor investments. Our oil-free air compressors, renowned for reliability, performance, and energy efficiency, will revolutionize the way compressed air is used in the railway industry” said Dr. Jairam Varadaraj, Managing Director, ELGi Equipments.

Picture credit – https://www.toprankers.com/exams/railway-development-in-india-1854-to-now/

Why ELGi Airmate Filters? 

Here are the three key values that the customers gain with the ELGi’s AF Series Filters.  

1. Best-in-class performance: These filters are third-party tested for performance of residual oil as per the class stated and handle capacity they are rated for with high efficiency (99.99%). 

1. Best-in-class energy efficiency: The AF series filters have the lowest pressure drop in their class and significantly save energy wastage. The lowest pressure drop of 0.35 bar (combination of wet saturated pre-filter, fine-filter, and dry carbon filter) at rated capacity with next-gen elements is about 30% lower than average competition.  

1. Best-in-class ten years warranty for housing:  The common problem with most housing is corrosion. While this corrosion doesn’t affect the filter’s performance itself, it adds particles of its corroded body (Al or Fe) to the air, thus making it unfit for sensitive applications. With this warranty, customers can have a reliable, pure operation for the entire life of the filter. 

The above value proposition is backed by tests (as per ISO 12500 standard), validation data, and third-party certification. The maintenance of these filters for changing the elements is made reliable and simple. The differential pressure gauge gives the actual condition of the element, i.e., three coloured indicator helps in easy identification of filter element life and planning the maintenance activity. They also come with an element-time strip indicator that helps alert the user for on-time replacement of elements, thus never missing the reliability and quality of air needed by any user. You can contact ELGi application engineers or the nearest sales representative to select the right product for your application.

Application of Downstream Filters

How to remove contaminants from your compressed air system?

The atmospheric air comprises of moisture, particle contaminants, microorganisms, and gases. When this air gets compressed, the concentration of such particles increases by 6-10 times. However, when an air compressor compresses this atmospheric air, other contaminants like oil and metal traces get added during the compression process. This is why it is important to remove these contaminants from the compressed air before using them for any application.

These contaminants can be categorized into:

1. Particles
2. Water (Liquid, vapour, and aerosol)
3. Oil (Liquid, vapour, and aerosol)
4. Microorganisms
5. Other gases

According to the International Standard, ISO 8573-1:2010, compressed air contaminants like particles, water, and oil are segregated as per purity classes. In this standard, microorganisms and other gases are not included. As a result, the air purity is indicated as [P, W, O] and is ordered as per the number of particles, water, and oil.

Based on the application requirement, contaminants are to be removed from the compressed air using suitable downstream equipment. For instance, particle, water, and oil contaminants can be removed from the compressed air using downstream filters.

• Bulk moisture separatorsare recommended for removing the water from the compressed air. It is mandatory to have a proper automatic drain along with the moisture separator, as they are mostly used after the cooler. The optimal removal of condensate will ensure that no bulk water carry over to the downstream equipment. It is recommended to use a level sensing zero loss drain along with a moisture separator to get this done with minimum loss of air.

Downstream filters are available in various configurations/types. These can be categorized as per the residual oil and particle after filtration and are as follows:

1. The Coalescing filters are recommended to remove the wet particles and aerosols (water and oil) from the compressed air. Different types of coalescing filters are available based on residual oil and particle content at the filter outlet after filtration. Coalescing filters are classified into pre filters and fine filters.

• • With the Pre-filter, class 3 or 2 purity of particles and oil can be achieved, i.e., ISO 8573-1:2010 [2:-:2]

• The recommended sequence of installation is the bulk moisture separator followed by pre-filter

• With the fine-filter, class 2 or 1 purity of particles and oil can be achieved, i.e., ISO 8573-1:2010 [1:-:1]
  • The recommended sequence of installation is bulk moisture separator, pre-filter, dryer followed by a fine filter

2. The particulate filters are specialized to remove the dry particle and microorganisms from compressed air. This filter is mostly used after a desiccant dryer to ensure that the desiccant particles are not carried to the compressed air line.

• The class of purity of particles made possible with this filter is 3,4,5&6, i.e. ISO 8573-1:2010 [3:-: – ]
  • The recommended installation sequence is the bulk moisture separator, pre-filter, desiccant dryer, followed by the particulate filter.

3. The Carbon filters are recommended to remove the oil vapor and other gases present in the compressed air that are not removed by the coalescing filters.

• The class of purity achievable with carbon filter is “1”, i.e., ISO 8573-1:2010 [-:-:1]
  • The recommended preceding with carbon filter would be pre-filter, dryer, fine-filter, followed by carbon filter

Important factors to consider for having the right selection of filters to ensure optimal performance

• The filter capacity is based on the operating pressure of 7 bar/100 psi (nominal condition). In case the operating pressure is different, it is important to use the correction factor and select the filter model accordingly.
• The correct sequence of installing filters must be followed so that the performance is optimal. As a thumb rule, the level of filtration should be in sequence, ranging from 20 ppm to 5 microns or from 10 microns to 1 micron to 0.01 micron. Carbon filters should always follow after the 0.01 micron filter. Absence of this sequence will reduce the life of the filters.
• Please note that the lowest pressure drop across filters happens when the filter elements are dry. If the filter element gets wet, delta P will increase. This is another reason why we should follow the above sequence.

• It is recommended to have a proper drain along with the pre-filter since the pre-filter is mostly used before the dryer. The regular removal of condensate will ensure that no moisture carries over to the downstream equipment.

• The replacement of the filter element at the recommended service interval is important. The filters have an indicator of saturation level, and it is recommended to replace the filter element in case of indication. Saturated filter elements will not give the required class of purity. This will have a higher pressure drop, creating an extra load on the compressor. As a thumb rule, 0.14bar/2 psi pressure drop will have 1% additional load on the compressor. Carbon filters function on the adsorption method and need to be replaced on a timely basis.

In business, visual cues play a key role in creating customer delight and facilitating purchase decisions. While performance & utility of the product is important on one end, aesthetics can in fact make or break your product’s future.  

One such method of “selling an aesthetic experience” to customers is Spray Painting- making it the most prevalent paint application technique due to its versatility and economic viability.  

Compressed air plays a vital role in spray painting and there are multiple methods involved in the spray painting process including Air-atomized applicators, Airless spray, and High-volume, low-pressure (HVLP) spraying.  

Let’s take a look at each of these methods: 

• Air-atomized applicators are highly flexible and can be used on almost any kind of substrate, as the equipment can be adjusted and customized to suit the needs of the operator. Air-atomized applicator consists of a traditional spray gun that combines compressed air with liquid paint to create a pressurized mist that coats the surface.  
• Airless spray propels paint particles at a lower velocity than conventional air-atomized equipment, so there is less loss of paint through overspray. In this method, rather than mixing liquid paint with compressed air, airless application equipment simply forces the liquid coating through a narrow opening to create pressure.  
• In High-volume, Low-pressure (HVLP) technique the paint is released at a lower velocity, yielding less overspray and blowback than conventional air-atomized equipment. The HVLP spray equipment utilizes spray gun atomization technology that propels large quantities of low-pressure air to the gun applicator.  
  

While there are clear visible benefits in Airless and HVLP spraying, they require advanced skill on the part of the operator, making Air-atomized spraying technique the widely preferred one. 

Design of a spray gun 

Paint applied by a spray gun must be even and should not drip, hence the nozzles of spray guns are designed for handling expanding, non-turbulent volume flow with high exit speed.  
Spray guns can also have flat, broad or round spray nozzles to suit different applications.  

Types of spray guns & the compressed air requirement 

Type of spray, consistency and quantity of paint to be applied determines the operating pressure and the nozzle diameter of the spray gun which in turn determines the compressed air requirement. Typically, spray guns require compressed air in the pressure range of 2 to 6 bar with an average air consumption ranging between 10 to 20 cfm.  

Factors to be considered when sizing your compressor: 

A reliable compressor is key to achieving high quality paint finish consistently.  

1. When it comes to sizing air compressors for painting, operating pressure and flow offered by the compressor, are the critical factors to be considered. 
2. The next critical factor to consider is the compressed air quality that the painting application demands. Quality of air is defined based on accepted levels of contaminants such as water, particles and oil. The air produced by any compressor, contains the same substances as the ambient air. This means that apart from dust particles, the RH factor in the ambient air contributes to water vapor and the oil used in the compressor for lubrication purpose also gets carried along with the compressed air. 

It is recommended that the humidity is reduced by drying the compressed air with a refrigerant dryer, and particulate filters are installed, to reduce the amount of dust particles present in the compressed air.  

An activated carbon filter can also be used to ensure there is no oil in the compressed air system. When supplementing other filters with an activated carbon filter, one achieves a quality called “technically oil-free” compressed air. 

ELGi offers a wide range of oil lubricated and oil free Reciprocating and to choose from, along with the downstream equipment to suit vast range of applications. Our extensive network of authorized channel partners across the world can help to choose the best compressor model suiting your painting applications. 

Get in touch with a compressed air expert for your needs here: https://www.elgi.com/in/contact-us/

Having said that, the need for compressed air are many, based on various application in several industries. 

Selection of the right compressor can be a daunting challenge with several technologies and options available in the market. In this article, we attempt to simplify the process of selecting the industry’s most widely used air compressors; reciprocating and screw compressors for any given application.  

But remember, when in doubt, always reach out to our Compressed Air Experts! 

Factors to consider when selecting an air compressor:  

1. Quality of air 
2. Capacity of the compressor 
3. Duty cycle & utilization 

Quality of Air 

Industrial compressors have oil as the medium that cools, lubricates and seals gaps between the moving parts. As a result of this, compressed air is exposed to the oil and a part of it is carried over. 

In specific applications, compressed air comes in direct contact with products such as food and pharma, this is where oil free air is preferred.  

The quality of air based on the amount of this oil carried is represented by ISO 8573:2010. Class 3 allows for < 1 mg/m3 of oil carry over and a higher quality can be achieved through downstream filtration equipment.  

Depending on your application requirement, the selection of the air compressor will vary.   

Capacity of the Compressor Required 

The capacity of an air compressor is a function of volumetric flow of air and the pressure to which it is compressed. This also determines the power rating (typically in kW or HP) of the air compressor.  

Eg. A 22 kW (30 HP) air compressor can provide a flow of about 140 cfm (3.96 m3/min) at 7 bar g. (102 psi) pressure. 

Few ways to determine the capacity requirement of a plant is through the OEM recommendation, past equipment experience or through air audit. Air audits enable companies to get valuable insights into their plant’s compressed air utilization.  

ELGi’s air audits chart out a customized and comprehensive energy management plan for your needs. Reciprocating compressors are well suited for flow below < 50 cfm and for higher flow capacities, screw compressors are better suited, when comparing the two technologies. 

Duty Cycle & Utilization 

Duty cycle refers to the time a compressor is expected to run in a given hour at full capacity. Reciprocating compressors are designed to operate between 60-80% duty cycles and screw compressors are designed to operate at 100% duty cycle.  

Life cycle cost of a compressor constitutes Initial Cost + Maintenance Cost + Energy Cost  

(In a screw compressor, energy cost contributes to over 75% of the life cycle cost over 10 years’ operation time).  

It is critical to understand the life cycle cost of a compressor before making the purchase decision.  

For more understanding on the life cycle cost of a compressor, refer to: 
https://blog.elgi.com/knowledge-center/identify-the-real-life-cycle-costs-of-your-air-compressor/ 

The amount of time a compressor runs in a day influences the energy cost. While looking to select a compressor with optimal life cycle cost, follow these guidelines:  

1. When utilization is < 4 hours/day select a reciprocating compressor 
2. When utilization is between 4 and 8 hours/day, a belt driven screw compressor is preferred 
3. When the utilization exceeds 8 hours/day, a direct driven screw compressor is the best fit.

You can also use the product selector on our website, to match the products for your requirements.  

https://www.elgi.com/product-selector/  

Like any other machine, air compressors need regular maintenance and periodic replacement of parts that get strained with continuous use. By changing the worn-out components in time, you can ensure optimal functioning and better durability of your unit while also saving time and money on unnecessary repairs. 

While these spare parts are often available in the market, and in many instances even come at attractive price-points, it is critical to procure your air compressor’s components only from Original Equipment Manufacturers (OEMs).  

Benefits you enjoy when you purchase only genuine parts:  

• Warranty – for repair, replacement or refund if the part fails to function optimally  
• High product quality  
• Longer lifespan  
• Higher productivity  
• More energy savings  
• High reliability  
• Ease of service and maintenance  

Let’s take a look at the parts that need to be replaced or replenished for the commonly used rotary screw air compressors:  

Dust filters and oil separators  

The air & oil filters and the oil separators are critical parts of air compressors as they prevent damage and performance loss caused by dirt in the internal system.  

Dust particles from inlet air can damage your air compressor’s rotors. This can reduce the quantity of compressed air delivered to associated tools, with continuous energy consumption.  

Dust also lowers the lifespan of the air compressor element and the oil separator. When it gets mixed with the oil that lubricates the rotary screw air compressor, the oil becomes impure and less effective.  

Additionally, dust harms the bearings and the bearing housing, negatively impacting the air compressor element and may even lead to element seizure. 

Therefore, it is essential to use only genuine air compressor filters and oil separators when it is time to replace the originally-fitted units. Such filters have strong dirt reduction capabilities. They are devised to endure high operating pressures and fluctuating temperatures while maintaining efficient performance with low power consumption.  

Airline filter cartridge   

If you replace your air compressor’s line filter cartridge with a counterfeit piece, it will reduce the filter’s efficiency and allow dirt particles to enter the air network. This will result in pressure drops and high energy consumption by the compressed air system.  

Using a non-genuine filter cartridge will also result in more frequent replacements or repairs, leading to a higher total lifecycle cost of the air compressor. Hence, always insist on buying genuine airline filters.  

Lubricating oil 

A key consumable in oil-based air compressors, is that the lubricating oil absorbs heat while also safeguarding the unit from dust accumulation and rusting.  

While some users have a notion that ‘any oil’ can be used for lubrication, the fact is that a poor quality oil reduces the durability of an air compressor. If oil greases the system components ineffectively, it can cause the formation of sediment in oil circuits and over the moving parts. Such developments increase the risk of oil oxidation and corrosion of metal parts in the compressed air system. 

Using genuine oil or lubricating fluid offered by your air compressor supplier can ensure effective lubrication, prevent equipment breakdown and derive better performance from your rotary screw air compressor.  

Authentic air compressor oil combines the finest quality of case oil with required amounts of additives that make the product suitable for lubricating an industrial compressed air system.  It is viscous at low temperatures and has high oxidation resistance. 

With a genuine lubricating oil, you will need to top-up less frequently, have lower disposal cost, require less maintenance and face lesser downtime incidents.  

Important points for you to take note: 

Besides procuring spare parts and consumable fluids from OEMs and recognised suppliers, it is also critical to have a proper service kit comprising the hand tools for safe replacement of parts, and for best results, you should get your compressed air system serviced only by experienced repair personnel.  

ELGi offers a range of industrial-grade air compressors for reliable functioning. We also provide bona fide spares that maximise the uptime of your air compressor system and reduce operating costs. With our Annual Maintenance Contract (AMC), you get the assurance of always getting compatible and long-lasting parts along with on-time service by professionals. To know more about our solutions, visit https://www.elgi.com/in/services-parts/