The Two Main Types: AC vs. DC

• AC (Alternating Current) Motors: These are powered by the kind of electricity you get from the wall outlet. They come in two main categories:

  • Synchronous Motors: Maintain a constant speed regardless of load. (Example: Permanent Magnet Synchronous Motor)

  • Asynchronous Motors: The most common type of AC motor. They are found in appliances, power tools, and industrial machinery due to their simplicity and durability. (Example: TEFC Induction motor)

• DC (Direct Current) Motors: Powered by batteries or rectified AC current. They offer good speed control and are often used in:

  • Battery-powered devices like toys and drones.

  • Industrial applications where variable speed is crucial.

Specific application-based motors,

Beyond AC and DC, there are motors designed for specific tasks:

• Servo Motors: Offer precise positioning control, perfect for robotics and CNC machines.

• Stepper Motors: Move in discrete steps, ideal for applications like printers and positioning systems.

• Linear Motors: Generate linear motion directly, eliminating the need for gears or linkages.

Design and Construction

Based on the part of the world we live in, two major organizations set the guidelines for electric motor design: The National Electrical Manufacturers Association (NEMA) in the Americas and the International Electrotechnical Commission (IEC) for most of the rest of the world. These organizations also set design and efficiency standards.

Design

NEMA uses imperial units (inches) while IEC utilizes the metric system. NEMA motors typically have a side-mounted conduit box, whereas IEC motors have a top-mounted one. Mounting hole spacing and shaft sizes also differ between the standards. They differ to the level of using different types of lubricants.

Speeds

The speed of motors is based on the construction of the motors, there are 2, 4, 6 and 8 pole motors, where the shaft speed is highest in 2 pole and the lowest in 8 pole motors. Speeds affect efficiency levels.

Efficiency

Motor efficiency refers to the conversion rate of electrical energy into mechanical energy. A higher efficiency means less wasted energy, translating to lower electricity costs and reduced environmental impact.

NEMA currently has one efficiency limit in use now (NEMA Premium), that all manufacturers have to meet across all NEMA regions. When it comes to IEC, there are multiple efficiency levels (IE1, IE2, IE3, IE4, IE5) and a few regions also have regulations that state minimum efficiency and performance standards.

The efficiency levels are not static, they keep increasing as the size of the motor increases. Also, speed of the motor affects the efficiencies, while they are close to each other, 4-pole motors have the highest efficiency among the different motor configurations and all ELGi EG and EQ machines use 4-pole motors.

When comparing the efficiencies NEMA Premium sits between IE3 and IE4 IEC efficiency levels. Induction motors (Asynchronous) based on the current technology can achieve a maximum of IE4 efficiency levels.

For motors with efficiencies greater than IE4, synchronous motor technologies offer the solution. While Synchronous reluctance motors and assisted synchronous reluctance motors help achieve IE5, to achieve efficiencies higher than IE5 limits permanent magnet synchronous motors are the solution.

Now, we had stated that the efficiency limit established by standard stops at IE5, then why the need to make more efficient motors? For the benefit of power conservation and environment protection!

This is where and why ELGi has gone beyond standards, leveraging internal technology research and advanced manufacturing methods ELGi had developed the most efficient Permanent Magnet Synchronous Motors used in the compressor Industry, the ELGi TORQPM motors. How efficient are these motors? IE5 efficiency limit for a 37kW Synchronous motor running >1800 rpm is 95.8% whereas the 37kW ELGi TORQPM motor that powers the EG PM series of VFD machine exceeds the requirement at 97.5% a good 1.7% higher than the regulation. Hypothetically, if an IE6 were to be released or even an IE7 standard then these motors will meet them.

At ELGi, we push for greater efficiencies and a greener future.

Regulatory references,

IEC 60034-30-1 / IEC 60034-30-2

Why recover heat? 

All the electrical power used during the compression process is converted to heat. This heat, if not recovered, causes a waste of energy- which contributes to global warming. When heat is recovered, the cost of power is reduced, which, in turn, reduces the overall cost to companies. When heat is not recovered, it is released into the atmosphere, thus causing wastage. 

When the heat recovery system is plugged into an air compressor, the energy recovered can be used to heat water for use in showers and boilers.  

How is the heat generated in the compressor system used? 

In an average compressor, 96 per cent of the heat can be theoretically recovered – this includes heat from the oil cooler, the after cooler, and the drive Motor. The heat released by the oil cooler can be used for the purpose of heating water. On the other hand, the heat generated by the aftercooler and the drive motor are used for supplemental space heating.  

Why choose ELGi’s heat recovery system? 

ELGi’s heat recovery system recovers upto 78 per cent of the heat generated. This eliminates the need for additional equipment that would lead to more energy consumption and CO2 emissions. With ELGi you are also assured of a greater return on investment.  

ELGi’s Heat Recovery System is an accessory that can be plugged into the EG series rotary compressor – owing to its fully enclosed design. This system is crucial to the functioning of various industries- automotive, cement, textiles, and steel making, to name a few.  

In line with ELGi’s efforts towards sustainability, the Heat Recovery System leads to extra savings and reduced carbon emissions 

The HRS from ELGi saves 69% of the fuel and provides faster ROI* 

 A thorough understanding of how your compressed air system works helps in improving its performance. To know more about  the energy management solution or the heat recovery system, please contact our sales team. 

*this may vary as per site conditions and end-use. 

The ratio between the active power and the apparent power cos Ǿ is known as the power factor. 

The line current drawn by induction motors consists of two components, Magnetizing current and Power-producing current. 

The magnetizing current is the current which is required to produce the magnetic flux, and this component is lagging the voltage vector by 90 Deg (Lagging because vector rotation is anticlockwise) 

The power-producing current is the current which reacts with the magnetic flux to produce the machine’s output torque of the motor, and this component is in the time phase with the voltage. This means that the phase of the motor current (vector sum of the magnetizing and power-producing current) will be displaced about the network voltage by the angle Ǿ 

Why raise the power factor? – 

A motor running under no-load consumes almost only reactive power. 

Active power: The power consumed in an AC circuit is called active power. Active power is the power that continuously flows from source to load in an electric circuit. 

Reactive power: Reactive power is the power that continuously flows from source to load and returns to the source in an electric circuit. 

Plants containing many motors consume a considerable amount of reactive power. If the machines run at no load for a more extended period. In that case, the reactive power requirements will also be large compared with the need for active power, and the power factor can become very low, affecting the power tariffs. In this condition, it is a must to correct the power factor.  

By improving the power factor, we can achieve extensive savings. 

The total apparent power of the utility power will reduce, reducing the generating losses throughout the complete supply and distribution system. 

A higher power factor reduces the load on transformers and distribution equipment.  

The losses in transformers and distribution cables are proportional to the square of the line current. So, a high-power factor will result in a direct saving of electric power. 

How to improve the power factor: – 

The reactive power component (KVAr) must be reduced to improve the power factor for a given load.  This component of reactive power lags the power component by 90 Deg.  So, one way to reduce the effect of this component is by introducing a reactive power component that leads the power component by 90 deg. This can be accomplished by using a power capacitor, as shown in the power diagram resulting in a net decrease of the angle Ǿ=Ǿ1-Ǿ2 of an increase in the power factor. 

The amount and location of the corrective capacitors must be determined from a study of the distribution system and the source of the low-power factor loads. 

Where to locate capacitors: 

The power factor correction capacitors should be connected as close to the low-power factor load as possible to reduce the system losses. 

In some cases, the capacitors can be located at a specific power feeder. 

In other cases, with large motors, the capacitors will be connected as close to the motor terminals as possible. 

The power factor capacitors are connected across the power line in parallel with the low-power factor load. 

The circuit diagram, power capacitor connected to the motor terminals. 

Connecting the power capacitors at the motor terminals and switching the capacitors with the motor load is a very effective method. No extra switch or protective devices are required and the line losses are reduced from the point of connection back to the power source. Corrective capacitance is supplied only when the motor is operating. 

The following points have to be considered. 

It is necessary to reduce the overload relay setting to maintain proper overload protection. 

Never connect the capacitors directly to the motor when open transition starting is used such as star-delta and autotransformer. 

In this case, self-excitation voltages or peak transient currents can cause damage to the capacitor and motor. 

In these types of installations, the capacitors should be switched with a contactor interlocked with the motor starter 

Size of the capacitor to be installed: 

The size of the capacitor should not be too large if the power factor correction on the motor is directly applied.  When the motor is disconnected from the supply, it runs as a generator as long as it rotates and the capacitor supplies the magnetizing current. 

If the capacitor is too large, it will produce a higher magnetizing current than expected, generating a higher voltage than its rated voltage. 

The selection of capacitors should be with a maximum rating corresponding to 90% of the no-load output of the machine. 

Air compressors consume significant amounts of energy to supply power for industrial applications. If you consider all the costs of running capacity, you will realize that any savings therein will lead to a positive impact on your overall power cost management. 

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.

Water vapor in the compressed air needs to be eliminated to prevent damage & corrosion to the compressed air line & your pneumatic tools. The operational expenses may go up significantly, if this moisture is not eliminated from the system.  That is why compressed air dryers are critical to industrial manufacturing processes as they help in removal of moisture from the compressed air lines.

 
Different dryers for diverse applications 

Depending on the application, compressed air dryers come in different capacities and types. Each of these dryers is unique, with its benefits and disadvantages: 

1. Refrigerated air dryers 

Out of all the compressed air dryers, the refrigerated air dryer is the most popular and used across several applications. 

 Functions: 

• Cools compressed air to very low temperatures, allowing moisture suspended in it to condense into its liquid form.  
• Once the water has been removed, a dry stream of air can flow towards the application. 

 Application: 

Useful in manufacturing & service applications that require compressed air with no detectable condensable moisture. 

 Benefits: 

• Cost-efficient – both in purchase and maintenance. 
• Resistant to airborne oil particles.

 Considerations: 

• Not ideal for sub-freezing temperatures.
• Have a limited dew point capacity.

2. Desiccant air dryers 

They are usually the second step after a primary dryer like a refrigerated dryer. 

Functions: 

Utilize a porous hygroscopic medium like activated alumina, molecular sieve and silica gel to extract moisture from the air and dry it.  

Applications: 

Useful in moisture-sensitive industrial and commercial applications: 

• Mold & bacteria prevention. 
• Healthcare/medication prescription environments. 
• Food processing. 
• Textile manufacturing. 

 Benefits: 

• Constant, low dew points. 
• Moderate operating costs. 
• Suitable for use in harsh, isolated environments. 

Considerations: 

• High setup costs. 
• Air filtration needed to prevent desiccant degradation from suspended oils. 
• Purge air is often required.

3. Deliquescent air dryers 

Single Tower Desiccant dryers are used in smaller, more specialized applications where a continuous supply of clean, dry compressed air is not required. 

Functions: 

Utilize a porous hygroscopic medium like activated alumina, molecular sieve and silica gel to extract moisture from the air and dry it.  

 Applications: 

Useful in moisture-sensitive industrial and commercial applications: 

• Mold & bacteria prevention. 
• Healthcare/medication prescription environments. 
• Food processing. 
• Textile manufacturing. 

Functions: 

• The deliquescent desiccant type of dryer uses a hygroscopic desiccant material having a high affinity for water.  
• The desiccant absorbs the water vapor and is dissolved in the liquid formed.  
• These hygroscopic materials are blended with ingredients to control the pH of the effluent and to prevent corrosion, caking and channeling.

Benefits: 

• Low initial capital and installation cost.
• Low pressure drops. 
• No moving parts.
• Requires no electrical power.  
• Can be installed outdoors.
• Can be used in hazardous, dirty or corrosive environments.

 Consideration: 

• Limited suppression of dew point.  
• Desiccant bed must be refilled periodically.  
• Drainage of dissolved solution.  
• Regular periodic maintenance.  
• Desiccant material can carry over into down-stream piping if there is no after-filter and if the dryer is not drained regularly. Certain desiccant materials may have a damaging effect on down- stream piping and equipment.  
• Some desiccant materials may melt or fuse together at temperatures above 80°F. 

4. Membrane air dryers 

Efficient option for compressed air drying. 

 Functions: 

• Utilize specialized membranes containing microtubules to filter moisture.  
• The microtubules retain water while a stream of the dried air is permitted to flow through to a collection unit or required application. 

 Applications: 

Used in applications requiring dehumidification, food processing, and gas separation. 

 Benefits: 

• Remote operation without the need for electricity. 
• Quiet operation, no moving parts. 
• Easy maintenance. 

 Considerations: 

• Only be operated with uncontaminated air. 
• Require regular filter changes to prevent blockages. 

ELGi’s solution for moisture sensitive industries 

ELGi’s Airmate Desiccant Dryer is a heatless twin tower desiccant dryer that removes moisture through absorption onto a granular desiccant bed from the air supply. As compressed air flows up through a packed bed of desiccant in tower 1, water vapor is absorbed. Meanwhile, tower 2 is rapidly depressurized, and dry purge air from the outlet of tower 1 is fed through a purge valve, expanded to near atmospheric pressure, and counter-flowed down through tower 2 to affect the regeneration of its granular desiccant bed. When the desiccant in tower 1 becomes saturated with water vapor, the air supply is switched back to tower 2 after it has been re-pressurized, and the cycle continues.  

As default, all HLD models above 5X come with the following options. 

 Dew Point Stretch Cycle: It stretches the moisture loading time of the desiccant bed by increasing the drying time. A dew point meter at the outlet with a required dew point setting provides the signal for the stretch cycle. This reduces the purge of air per the air flow and dew point chosen. The purge occurs for the pre-programmed time during this time.  

Note – Dew point meter not in dryer scope.  

Purge Optimizer: It reduces the percentage of regeneration flow based on the front panel setting. It has 4 options 40%, 60%, 80% & 100% purge optimization cycles respectively. The settings correspond to flow or moisture load through the dryer. Separate LED Indicators for Tower Status, Purge Optimizer & Condensate Drain.  

To make sure that you choose the ideal air dryer for your system, here are some things to keep in mind: 

• Select the air quality your business requires. 
• Invest in high-quality systems, resulting in cost & time efficiency. 
• Get in touch with an ELGi expert; they can assist you while navigating ELGi’s range of air dryers.

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 

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.

Therefore, businesses equip their manufacturing processes with screw air compressors.

So, what are screw air compressors?

Screw air compressors or rotary screw air compressors are an advanced version of the original piston air compressors. Using a rotary type positive displacement mechanism, they are the workhorses that provide large volumes of medium to high-pressure air in large factories. The screw air compressors find their use in food production, beverages and medicines, construction, mining, petrochemical engineering and more.

Types of rotary screw air compressors:

Industries and manufacturing plants widely use two types of rotary screw air compressors: oil-free and oil-lubricated rotary screw air compressors. Each of these is unique in their way and are suited for specific purposes.

Oil-free screw air compressors:

In an oil-free screw air compressor, the air is compressed entirely through the action of the screws without the assistance of oil lubrication. Instead, PTFE, distilled water or other proprietary coatings are used for lubrication and heat dissipation. They usually have lower to medium discharge pressure capability as a result. However, higher pressure can be achieved by multi-stage oil-free compressors, where the air is compressed in multiple stages.

Oil-free screw air compressors are used in applications where even the slightest bit of oil contamination cannot be tolerated, including the production of food and beverages, medicines and medical research, packaging, and more.

Oil-lubricated screw air compressors:

Oil is injected into the compression chamber to aid lubrication and adequate heat dissipation in an oil-lubricated rotary screw compressor. The oil is separated from the discharge stream, cooled, filtered, and recycled.

Oil-lubricated screw air compressors are used in applications that require or can tolerate slight levels of oil, such as tools, heavy drilling and mining, metallurgy, mobile tire services, and more.

Benefits of screw air compressors

A. Continuous flow: There is no disruption in the delivery of air for any application.

B. Flexible and durable: They can be designed for extreme weather conditions as well.

C. Lower maintenance costs: The innovative design is ideal for customer needs, ensuring that the equipment functions smoothly and hence no unwanted costs.

D. Low noise output: These compressors run quietly and provide a safe working environment.

Rotary screw air compressors by ELGi:

The rotary screw air compressors are the backbone of most industries across the globe. The proprietary airend design, advanced features, and innovative technology offer cost-effective, long-lasting, reliable, and premium compressed air perfectly suitable for light to heavy-duty industrial applications.

AB series

ELGi’s new AB series screw air compressors provide disruptive benefits in terms of efficiency, reliability, and air quality, resulting in lower life cycle costs and high uptime.

The high-quality air output with Class ‘0’ certification makes ELGi’s screw air compressor ideal for sensitive applications like producing and manufacturing food and beverages, pharmaceuticals and medicines and medical research.

EG series

A trusted solution for partners from across the globe, the EG series air compressors from ELGi are highly efficient, reliable and have a long life. These features of the air compressors support the packaging industry in maintaining quality, safety, and reliability.

You can reach out to our air experts for support with your business: https://www.elgi.com/in/rotary-screw-air-compressors/