ELGi’s Oil-Free Air Expert addresses query frequently asked by users from various industries. 

Q1. I am setting up a new pharmaceutical bulk drug manufacturing plant. Which compressor should I select? 

The quality of compressed air is critical in applications where the air comes in direct contact with the end product. It should not contain contaminants like oil particles. One more requirement of the pharma segment is uninterrupted operation. Hence, the most suitable solution will be an Oil-Free screw air compressor which is best suited for continuous duty application and delivers compressed air, free from oil contaminants. 

Q2. How is an Oil-Free compressor different from a lubricated compressor? 

In the lubricated compressor, oil is injected into the compression chamber, also called the Airend, during the compression process. This lubricating oil mixes with air, and this Air-Oil mixture is further treated. 

Whereas in an Oil-Free compressor, during compression, there is no injection of oil into the Airend.  Hence, the compressed air does not contain any traces of oil. 

Additionally, Oil-Free air compressors are also eco-friendly since there is no oil spillage from the compressor drain or oil carryover in compressed air. 

Q3.I have fluctuating airflow demand. How can I reduce my operating cost? 

While some setups have a fixed airflow requirement, many factories might be experiencing fluctuating demand. This situation allows us to reduce our operating costs significantly. 

As a best practice, if your airflow demand is not constant, we recommend installing a VFD-equipped air compressor. If you have a fixed air compressor installed already, you can opt for a Retrofit VFD kit matched to your compressor power, which can help regulate the airflow as per plant requirements and reduce power costs. 

Q4. What are the different cooling methods used in Oil-Free air compressors? 

Electrical energy is converted into thermal energy during the compression process. Cooling systems are designed to maintain the system temperature within acceptable limits. 

ELGi offers Oil-Free air compressors in both Air-cooled & Water-cooled variants. 

Q5. My application is critical. How can I be sure that the compressor delivers Oil-Free air all the time? 

The compression process occurs in the compressor chamber called the Airend. An Airend has two sides, the airside and the oil side, which are completely isolated by air & oil seals, which prevent oil from mixing with air. 

ELGi Airends have an additional safety arrangement, wherein even if the seals, for some reason, malfunction, the oil will go back into the sump and not mix with air. Thereby always guaranteeing 100% Oil-Free compressed air. 

Q6.  What all industries use Oil-Free compressors? 

Specific industries require air that directly contacts the end product or is used for sophisticated machines. The presence of oil traces in such scenarios is highly undesirable. 

ELGi offers 100% Oil-Free compressed air solutions to Pharmaceuticals, Food & Beverage, Textile, Automobile, Electronics, FMCG, Oil & Gas, Power, and many more. 

Q7. How does ELGi ensure the high quality of its air compressors? 

Air compressors from ELGi are designed to offer the highest product quality & system reliability to our customers. 

We are one of the very few manufacturers in the world who have their Airend design and build them entirely in-house. 

 Another example of our efforts to go the extra mile is our state-of-the-art foundry set-up to achieve the highest quality in casting. 

Q8. How do I select a suitable air compressor for my application? 

Air compressor selection depends on several factors. A few questions to ask before finalizing one for yourself are – 

– What is the airflow or SCFM required by your pneumatic machines? 

– What is the operating pressure? 

– Does your application need Oil-Free air? 

– Is your airflow demand fluctuating?  

With so many factors to consider, the selection process might seem overwhelming. ELGi offers a wide range of air compressors – Oil-Free and lubricated piston and screw air compressors.  

ELGi’s compressed air experts can help you identify the right solution for your application. We also conduct extensive air audits to map airflow demand accurately to get the most efficient solution. 

To know more, click here.

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.

SCUBA stands for “Self Contained Underwater Breathing Apparatus” and it is the paramount element of marine exploration.  

The major aspect that confines our time and experience underwater is the air that we carry in our SCUBA tanks.  Air, Ah!! It’s simple when we hear it as a term in itself. But when it comes to using air in SCUBA, we must understand its forms first.  

Right from our early schooling we have learnt that the air we breathe is a composition of nitrogen and oxygen majorly, as well as water, carbon dioxide, ozone, and many other compounds in small traces. But little did we know that the same atmospheric air is compressed, to utilize as a fourth form of energy in many industrial applications. The pressure range in which air is compressed depends on the use case. While for SCUBA, normal atmospheric air is compressed and filtered, so the divers can take more of it with on their underwater trip.  

Compressed air is the typical gas used for recreational diving, while Nitrox, Trimix and Heliox gas mixes are used for technical diving in deep waters. Divers use a pressure regulator (in their mouth-piece) to bring back the air from high pressure to atmospheric pressure (when at the surface) or the local underwater pressure, depending on the depth.  

While underwater, compressed air is utilized at varied levels which is a factor of the depth it is breathed at. For us to visualize – If you are a diver descending into the ocean, for each foot you will experience an increase in pressure by 0.44 psi roughly for sea water and this is a tad bit less for freshwater SCUBA as both the air pressure at the water’s surface, and the water pressure, will act.  

The scuba diver uses a mouthpiece with a pressure regulator to retrieve the air from high pressure to atmospheric pressure, or to the required pressure based on the depth. 

SCUBA tank filling air compressors are similar to the ones used to deliver air for firefighters and for oxygen tanks in hospitals but the vital difference is the pressure and compressed air quality output from the compressor. 

1. Pressure

For SCUBA, when compressed air is being used, based on the way air is carried, a low pressure or a high pressure compressor is chosen.  

a. Low-Pressure Compressors 

For surface supplied diving, low-pressure compressors are used. These compressors are lighter in weight compared to the conventional compressors so as to carry in flotation rings that float on the surface of water and they supply underwater divers with air via a hose. Typically pressure range for surface- supplied diving compressors range from 15 psi to 130 psi maximum.  

b. High-Pressure Compressors 

Divers carry compressed air in Aluminium or Steel tanks for breathing underwater, in this scenario air is compressed in ranges between 3,200 and 5,000 psi.  

The compressor’s Free Air delivery/ output flow is a factor of the tank size and number of tanks that needs to be filled. 

Compressed air quality 

For SCUBA it is mandatory that the compressed air is of breathing quality. A compressed air system can contain contaminants that affect the quality of breathing air from sources like compressor oil, system leaks, inadequate filtration and environmental variables. Hence filtration plays a crucial role. 

Mostly the filtration and moisture separation system is separated from the compressor system, hence downstream filters, moisture separator and dryers are preferred, to ensure the compressed air complies with breathing air standards. Apart from regular filtration, the compressed air is passed through a sequence of activated carbon filters that gets rid of hydrocarbons and carbon monoxide (CO).  

We must keep in mind it is important to choose the right compressor that inherently does not pass over excess moisture, oil, dust particles and other contaminants as excess moisture can cause overloading of the drier, and moisture separator. If left unnoticed, it may lead to deprivation of compressor filtration, fault in regulators, corrosion and oxidation of scuba tanks. While excess oil could increase excess CO, CO2 and hydrocarbon levels in compressed air. 

In order for humans to have a safe and fun underwater experience, making sure you have the right tank and air supply is essential for a successful dive. At ELGi, all our compressors are built with best in class features unique to our brand for keeping moisture and oil carryover as much within the limits as possible. We study the application in-depth before suggesting the compressed air system with the suitable air quality and right size.   

Schedule a call with an air expert here: https://www.elgi.com/in/contact-us/  

Author – Gopikrishna 

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/  

Major operations of the ready-made garment industry fall under these three categories:

1. Pre-production
2. Production
3. Post-production

Pre-production: This phase involves arranging materials, line planning, sample development and approval, sourcing, and production scheduling.

Production: During production, fabrics are spread, cut, bundled, and sewn.

Post-production: Post-production includes inspection, pressing, folding, and packing, making the garment ready to sell.

The labour dependent nature of cutting and sewing makes the readymade garment expensive. Fabric costs and cut-and-sew costs are two of the largest expenses in garment manufacturing. While raw materials contribute up to 50 to 60% of the total product cost, sewing contributes approximately 35% of the total cost.

Efforts have been made to lower labour costs through supply chain management by locating production facilities in developing countries like India, Bangladesh, etc. However, this strategy is becoming complex and difficult to sustain, forcing the industry to find alternative solutions. Thus, automating ready-made garment manufacturing processes are becoming the need of the hour!

Automation not only improves productivity, but also the quality of the finished product by minimising human intervention and preventing errors. Some of the automated techniques adopted by the industry includes:

1. Mechanised fabric handling
2. Computerised cutting
3. Automatic sewing
4. Use of robots

“We don’t have to engage in grand, heroic actions to participate in change. Small acts, when multiplied by millions of people, can transform the world.”
– Howard Zinn

Sustainability lies at the core of ELGi’s business. Whether it is developing energy-efficient products or creating eco-friendly green hubs for workspaces, sustainability is integral to the corporate identity and is actively advocated by employees.

This is why, to honour the 50th Anniversary of World Earth Day on 22nd April 2020, ELGi launched the ‘Steps For Change’ programme, a purpose-driven engagement activity. Through the initiative, employees across the globe were encouraged to take small, yet significant measures and make a difference towards the environment.

According to the report, ‘All India installed capacity (in MW) of power stations’ published on 31st March 2020, India’s installed utility-scale hydroelectric capacity was 46,000 MW. This accounted for 12.3% of its total utility power generation capacity.

In the future, it is estimated that India’s hydroelectric potential shall reach up to 148,701 MW. Furthermore, it is said that an additional 6,780 MW from smaller hydro schemes which have capacities of less than 25 MW can be deemed as exploitable.

Apart from this, a total of 56 sites for pumped storage schemes with an aggregate installed capacity of 94,000 MW have also been identified.