Denim Manufacturing Process from Fiber to Finishing

What is denim:
Denim is a firm durable twill cotton fabric which woven with colored warp and white filling threads. Technically speaking, denim is a warp faced twill weave fabric. Here coarse and lower  yarn count  is used. So it is heavy fabric.

History of denim:
  Denim is one of the oldest types of work cloths that is available in the fashion world. It is used for its durability and comfort. Denim comes from the French phrase “Serge de Nimes”. The 17th century “Serge de Nimes” was introduced in French. Those fabrics were produced by using a mixture of cotton and wool. Some historians believe that it was first worn by sailors of Portugal. Initially it was worn by mechanics and miners. In the 21st century denim comes in many different styles including carpenters, sportswear, khakis, chinos and combat. Now it is true that the millions of people around the world favorite choice is denim cloth.




Types of denim fabric:
There are various types of denim. Most popular types of denim are given below: 

1. Dry denim
2. Selvedge denim
3. Stretch denim
4. Color denim
5. Reverse denim
6. Vintage denim
7. Ecro denim
8. Marble denim
9. Crushed denim etc

     


                                                                                            

1. Dry denim:
Dry denim is opposed to wash denim that means unwash after being dyed during its production.

2. Selvedge denim:
Selvage denim is a self-finished denim where the edge ensures the fabric won't unravel. It is made on a shuttle loom that means the resulting fabric is narrower. Selvedge denim has become more desirable than non-selvedge. Selvedge tends to have a tighter, denser weave than non-selvedge.

3. Stretch denim:
Stretch denim is a relatively new type of denim fabric. This type of denim is made with cotton or cotton/polyester blend that incorporates a small amount of elastane, a stretchy, synthetic fiber, also known as Spandex, or Lycra, into the fabric. Now stretch denim is popular for its relaxed fit.

4. Color denim:
Colored denim fabrics become woven. This denim is manufactured with dyed yarn either warp or weft. This kind of fabric can be obtained by piece dyeing process.

5. Reverse denim:
Reverse denim fabric is that, where the face side and reverse side are same.

6. Vintage denim:
It is old type looked denim. Vintage denim are made by heavy stone wash or a cellulose enzyme wash with bleach or without bleach. 

Denim Fabric Manufacturing Process:
Denim is 100% cotton woven fabric. So, it is strong and durable. Generally blue denim is warp faced cotton fabric with 3x1 twill construction where warp is dyed solid color and weft is undyed.

                                                                                   

Fig: Denim fabric manufacturing

Yarn for denim:
Lower count and coarse yarn is used for denim making. Fiber quality is not good. Denim yarn produced from open end spinning system. Probably the most important characteristics of the sliver is its cleanliness with particular care to be given to dust remove.

In ring spun yarn, a high incident of nep in the yarn will cause uneven dye uptake during the warp yarn preparation. It is observed that modern blow room line create neps. Up to an increase of 100% over neps in raw cotton that will still allow the carding machine to be able to remove most of these objectionable faults.

Coarse count yarn in denim refers to less than 8s Ne and fine count is 9s to 16s. Mixing requirements for rope dyed warp open end yarns are higher.

Dyeing and sizing process of denim yarn: 

 
In denim fabric, warp yarns are indigo dyed. There are various types of dyeing and sizing process which can be classified into four types. Such as-

1. Continuous indigo rope dyeing and sizing
2. Continuous indigo dyeing and sizing
3. Indigo back beam dyeing and sizing

1. Continuous indigo rope dyeing and sizing:
The yarn which we get from ring frame is wound into cheeses or cones and then placed on the ball warper on which 350-400 threads are formed into a rope. During this process, 12-24 ropes are dyed at a time based on the size of the rope dyeing plant.

2. Continuous indigo dyeing and sizing:
During this process, back beams are processed on the dyeing and sizing machine instead of ropes. The warp are dyed, oxidized, dried and sized at a once.

3. Indigo back beam dyeing and sizing:
According to this process dyeing and sizing is done in two stages. In the 1st stage, back beams are dyed, oxidized, dried and wound on a batch roll. The batch roll is then sized, dried and wound on a weaver’s beam.

Weaving process of denim fabric:
Weaving is done by interlacement of warp and weft threads, where warp yarns are indigo dyed. In this system warp thread is in the form of sheet. And weft thread is inserted between two layers of warp sheet by means of a suitable carrier such as shuttle, projectile, rapier, air jet, water jet etc. 

Finishing process of denim fabrics:
Final woven fabrics, which is wound on a cloth roll that we get from weaving machine at particular intervals and checked on inspection machine. So that any possible weaving fault can be detected. Then its goes through various finishing process. Such as brushing, singeing, washing, impregnation for dressing and drying. Brushing and singeing remove impurities and hairiness of the denim fabric. After complete all finishing process then it is sent to for garment manufacturing.

Denim fabric dyeing: Dyeing [rocess of denim fabric are two types. These are indigo dyeing and sulphur Dyeing. Indigo produce conventional blue color and shade alike to blue color. Sulphur dyeing is used to denim produce particular colors like black, cherry, grey, rust mustard and lime. Both are vat dyestuff. Both are insoluble in water and have a very poor affinity to cellulose fibers like cotton.

Denim washing process:
The wash out effect is achieved by removing dyestuff from fabric to get popular abraded, worn out look during washing process.

Wash can be divided into two types. Such as-

1. Mechanical wash
2. Chemical wash

1. Mechanical wash:
Mechanical wash contains garment wash, stone wash, sandblasting etc.

2. Chemical wash:
Chemical wash contains acid wash, enzyme wash, bleaching wash etc.

Popular washing of denim fabric:

Garment washing:
Garment wash is one type of short time wash. It is done for soft hand feel and natural cleanness. This type of wash is done by only water. Many time use detergent and many types of softeners. Finally the fabric is softened and lubricated.

 

     

  

Stone Wash 

Stone create a fading look in denim and increase softness and flexibility. This method has been improved by using other materials during wash. In this washing process the newly dyed jeans are put in washing machine and tumbled by pumice stones as abrasion. Stones have rough surface and remove some of the dyes particle from the surface of the fabric to give worn-out effect.

Acid wash:  
Acid Wash is one of the fashionable wash method. It can give the garments marble effect on the fabric surface and shaded look. In this process, pumice stone or rubber ball used with bleaching agent such as sodium hypochlorite or KMnO4. Then neutral the garments and dried. 


Enzyme wash:
In washing, enzyme wash is relatively new technology for denim to achieve the worn appearance and to provide soft hand feel. Enzyme remove indigo dye and hairiness of cellulose fibers from the fabric surface.

Bleaching wash:
The bleaching effect is done by using an oxidative bleaching agent eg. Sodium hypochlorite, calcium hypochlorite or potassium permanganate with or without stone addition. The dark blue shade is decolorized by the bleaching chemical which destroy the indigo dye molecules. .

Finishing process of denim garments:
Denim finishing will give your garments the final touch to create the right high quality fashion style. Getting the unique look with a superior reduction of back. Staining is fast and easy, wet and dry technique such as whiskering, brushing, crushing, washing, etc are all these technique give the fabric softer feel. Enhance its appeal without any strength loss and improve wear life. Resin finish is done for 3D effect.

Brushing/grinding:
Brushing/grinding (manual or mechanical) is used manually or mechanically for the worn-out effect, abraded look or used look. Some mechanical processes have been developed that are based on mechanical abrasion by which the indigo can be removed. Some of these processes are sueding, raising, immersing, peaching and brushing.

Advantages of these processes are as follows:

• Control of the abrasion.
• Different looks on the garment can be achieved.
• All are dry processes.
• Economical, ecological and environmentally friendly.

Brushing is generally being done in a rigid form of garments to get the distressed look. Locations can be front thigh and seat or it can be overall/global application as is standard. In the case of hand brushing, emery paper is used to brush the garments in particular places and designs. Emery paper comes in different numbers, generally starting from 40 to 600 and higher; the higher the number the finer is the emery paper (i.e. a lower is a more coarse paper). In the garment industry, 220, 320 and 400 paper numbers are most popular and widely used.

Figure-2: Marking the location for brushing

The purpose of this process is to impart a used worn look to the garments. The most important factor of brushing is to select the right sanding material according to the fabric strength and the intensity needed. Figures 2–4 show the brushing process in factory.

Figure-3: Hand brushing of denim

Figure-4: Mechanical brushing of denim

Grinding is done on pocket edges and bottom hems edges by rubbing them against an abrasive surface or stone to achieve a worn effect. Many different makes of machines and pen grinding tools are available in the market which run with pneumatic systems. Figure-5 and Figure-6 show the grinding effect on pocket edges and bottom hems, respectively.

Figure-5: Grinding mark on a pocket edge of jeans

Figure-6: Grinding mark in a bottom hem of jeans

Mechanical abrasion:
To give a worn effect or abraded or used look, some mechanical processes were developed. These are based on mechanical abrasion, which removes the indigo. Some of these processes are sueding, raising, immersing, peaching and brushing.

Advantages of these processes are:
Abrasion can be controlled.

• A different look to the garment can be achieved.
• All are dry processes.
• The processes are economically, ecologically and environmentally friendly.

Whisker:  
Wishkering refers to thin fading lines formed from creases that are usually found on the front pocket area of jeans. It is one of the most important design of a used look denim garment. Now a days it is a common drying process for denim wash.


Ozone fading:
Ozone destroys indigo color on denim in a manner similar to bleaching.O Zone Fading  of washed and bleached denim is primarily caused by the oxidative effect of ozone on the indigo dye, the contaminants and the applied additives. Ozone fading gives the advantage of fading with a minimum or hardly any loss.


Laser treatment:
 Laser Fading or marking is a popular dry process for denim now a day. A carbon dioxide (CO2) laser was used for the colour-fading treatment of denim fabrics. It is sustainable, environment friendly and emerging industrial approaches for the finishing treatments of the denim jeans.


Waterjet fading:
Hydrojet treatment has been developed for patterning and/or enhancing the surface finish, texture, durability and other characteristics of denim garments. Hydrojet treatment generally involves exposing one or both surfaces of the garment through hydrojet nozzles. The degree of colour washout, clarity of patterns and softness of the resulting fabric are related to the type of dye in the fabric and the amount and manner of fluid impact energy applied to the fabric. Particularly good results are obtained with blue indigo dyed denim. As this process does not involve any chemical, it is pollution free. A water recycling system can make this a very economical and environmentally friendly way of denim processing. Colour washout of dye in the striped areas produces a faded effect without blurring, loss of fabric strength or durability, or excessive warp shrinkage.

Dip dyeing:
In dip dyeing, dip dyeing machine is used to achieve special effects on denim garments. Direct dye is commonly used but the colour fastness is comparatively poor and therefore fixation is required to improve fastness. Pigments can also be used for dip dyeing. If a bleaching agent is used, bleaching effect can be achieved on garments.

Pigment washing:
Pigment washing is generally used on pigment dyed or printed garments by applying pigments.

Pigment washing is required for the following reasons:

• To get fading effect/old looking effect on garments and also the seam area.
• For a soft feel to wear the garment after purchasing.
• To achieve the buyer’s washing standard.
• To increase the colour and rubbing fastness.

Flow chart of pigment washing:

The basic steps of pigment washing are as follows:

Immersing garment in pigment

↓

Drying

↓

Baking (130–150 °C)

↓

Washing (with or without pumice stones/with or without enzyme, 30–90 min)

↓

Washing twice with water at 70 °C

↓

Removing stones

↓

Softening

↓

Drying.

Tinting:
After different types of process denim or jeans are dyed with very light color (.001% or .002% yellow or pink). This dyeing process is called Tinting/Overdyeing. Tinting of denim garments  is usually done after the stone wash process.  

Tie dyeing:
In tie dyeing, a rubber band or similar material is used to tie/bunch the denim garment to make different patterns. Then when carrying out dyeing with a direct dye, the dye cannot enter the tied portion. After dyeing, patterns can be created and fixation is needed. Pigments can also be used in tie dyeing. If bleaching agent is used, bleaching effect can be obtained, which is called ‘tie bleach’.

Plasma treatment on denim:
Plasma has been used in the treatment of textiles over the past 2 decades, but a generally available and implemented technology has yet to be developed. Nevertheless, several industrial devices are available as well as numerous examples of custom-designed plasma processing stages for specific industrial production lines. Two directions for development are atmospheric pressure devices and low-pressure plasmas.

There are numerous solutions for atmospheric pressure (or pressures of the order of several 100 Torr) devices, which include glow regime of dielectric barrier discharges and corona discharges. Low-pressure devices, in particular radio-frequency (RF)- powered plasma sources, allow easier control of properties and provide greater stability and uniformity at the cost of more complex handling of the fabric. Corona and RF low-pressure plasma treatments brought about an increase in denim lightness, indicating a removal of indigo dye from the fabric surface. The increased yellowness of the treated denim was more pronounced in case of corona and low-pressure plasma in air in comparison with low-pressure RF plasma in argon. This can be associated with the production of chemically active molecules and radicals in gas mixtures containing oxygen, which consequently leads to an oxidation of dyes.

Low-pressure plasma and corona treatments can be a viable alternative to conventional bio-stoning to obtaining the ‘worn’ look of indigo-dyed denim fabric. In addition to satisfactory colour change effects, the main advantages of these treatments are the lack of water consumption and shorter process duration. However, it requires further research to avoid an increase in yellowness and the appearance of a harsh fabric handle.

Corona and RF low-pressure plasma treatments brought about an increase in denim lightness, indicating a removal of indigo dye from the fabric’s surface. The increased yellowness of the treated denim was more pronounced in the case of corona and low-pressure plasma in air compared with low-pressure RF plasma in argon. The formation of pits and striations on the fibre’s surface was more prominent after low-pressure RF plasma than after corona treatment.

Conclusion:
Now a days denim garments is not only worn as a dress but also used for fashion purpose. Men and women both wear denim and jeans products. So improving quality day by day and increasing versatile variation in denim products.

TERRY TOWEL MANUFACTURING PROCESS

TERRY TOWEL MANUFACTURING PROCESS

Terry Towel, a pile fabric is known as towel worldwide. In terry towel loop piles are present on one or both side of the fabric. Terry fabrics are used in various fields because of their water absorption properties.

Different Parts of a Terry Towel

The parts mentioned on the above image are known in different names like

-Side Hem is named as Selvedge.

-Cross Hem is named as top and bottom hem.

-Borders are called as Dobby.

-Terry Bar is known as Cuff.

A wide variety of towel styles are available in the market. All the above towel parts may not be present in a particular towel.

Manufacturing of Terry Towel:

Terry towel weaving

Terry towel is one type of woven fabrics where during weaving of this fabric 2 beams are used. One beam for ground fabrication and other beam for loop formation. Top beam is responsible for loop formation by terry loom’s beat-up mechanism. Commercially 3 pick terry is most popular. 3 picks terry means after each 3 picks insertion full beat-up is made and one loop pile is formed of the fabric. See the following illustration of beat-up position.

Pile of the towel plays major role for a towel for its water absorbency and other properties. Loop length is decided by the quality, weight etc. as per requirements. Pile manufacturers use better quality yarn like combed, compact, hydro, zero twisted yarns.

Piles are made by different high value fibers like superior qualities of cotton suvin, giza, pima, bamboo, modal etc. to get better absorbency and lint properties. For ground yarn, comparatively coarser counts are used in OE and 2-ply option to give better strength and compactness in ground fabric. Both piles and ground yarns are prepared in the same manner of warping, sizing, and drawing-in.

Wet Processing of Terry Fabric

• Desizing
• Scouring
• Bleaching
• Dyeing
• Finishing

Dyeing Terry Towel Fabrics

Commonly used dyes:

• Reactive dyes

Commonly used machine:

• Winch, Jet/soft flow/overflow: Fabric in rope form
• Pad batch, Pad steam: Fabric in open-width form

Finishing Towel Fabrics

Chemical Finishing:

• Hydrophilic softeners
• Enzymatic softening
• Antimicrobial treatment (If no inherently antimicrobial fiber used)

Mechanical Finishing:

• Tumble drying: Gives softness, fullness, fluffiness
• Stentering:To straighten up fabric and impart dimensional stability

Cutting and Sewing

• Longitudinal cutting
• Longitudinal hemming
• Cross cutting
• Cross hemming

Basic Parameters of a Quality Terry Towel

• Weight & GSM: Weight and GSM should be same as required by customer. Every manufacturer has some template or software (ERPs) where towel manufacturers calculate everything likes pile’s height, density of picks and ends to meet requirement. This database or any software has been developed through some basic calculation.
• Softness/ Hand feel: It depends on properties of the yarn used in pile, finishing chemicals and too some extent on pile orientation.
• Pile Orientation: Totally depends on process line.
• Lint: Lint are basically protruding fibers present in a finished towel. It is measured by weight of accumulated fiber collected from washing machine and tumble drying machine during testing.
• Absorbency: Terry towel should be highly water absorbent.
• Dimensional Stability: How a towel is behaving after washing is fall under dimensional stability properties. Dimensional stability is measured by the residual shrinkage % in a finished towel.
• Other Parameters are strength, color fastness etc.

Savings in Compressor Air in Textile Mills

 Savings in Compressor Air in Textile Mills

  

Energy savings are a major issue in the functioning cycle of a textile mill. In the total electricity units consumed per day (UPD), the mill can reduce only around five to 10 per cent of UPD after energy audit and implementation. Compressed air leakage is a regular hidden cost in a mill. If not identified right away, it aggravates losses.

When a mill goes for modernisation, automated production demands more compressed air. So, instead of arresting existing air leakage, mills often buy more compressors to satisfy production demands. Ironically, leakage increases.

Why are there more losses in the compressed air system now?

The root cause is accumulation of water and dirt in compressed air pipe lines. This makes pneumatic fittings weak and leaky. A pneumatic fitting and component has a life. Beyond its life, leaks start. Soon, a drizzle turns into a shower.

The compressor post air cooler, refrigerated dryer and the zero air loss drain valves fixed in the air receivers at the compressor house, tail end and feed end receiver (Fig 1) are three sub-systems that have to work perfectly so that no water is trapped in the distribution and the load ends. More importantly, water ingress in the air actuation elements and solenoid valves in the machine will spoil their health.

Where is the loss happening in compressed air generation?

Compressed air generation is gets compromised if a compressor takes 5 to 10oC above the surrounding ambient temperature through choked air intake filters. This is two per cent KWH loss. Cool, dry compressors deliver more air output. So, try to give cool, dry air to the compressor air inlet as shown in Fig 5. Keep the load/unload settings to the minimum bar pressure just 0.7 bar, or 10 per cent above minimum required pressure demand from equipments.

Fix one pressure gauge just after the compressor and another gauge at the compressor house air delivery line/receiver. Fix a temperature gauge on the air receiver and keep its temperature 5oC above the ambient, which is a sign of unhealthy compressor package.

Fig 1. Invest in air receiver load feed/tail end model

Many mills have more pressure drop around 1 to 2 Bar in the compressor house. First, bring down the pressure drop to less than 0.7 Bar. We provide an air receiver in the compressor house to arrest the compressed air pulsation and fluctuation due to frequent loading and unloading of compressor.

Fig 2. Pressure sensor located inside existing compressor hood

Fig 3. Fluctuations in KW/KVA in every minute trend graph

The above images show that the location of pressure sensor (Fig 2) matters to us since this aggravates the cyclic fluctuation of load and unload (Fig 3). This can be solved by shifting the compressed air pressure sensor from the hood to the receiver. Many industries achieved savings and safety after shifting this pressure detection and control sensor to air receiver. Other encouraging option is to expand the compressor hot air exhaust so that the air and oil sub systems within the hood work comfortably.

How do you account for the compressed air losses in distribution?

Analogous to the other Transmission & Distribution (T&D) losses, compressed air lost in transmission is less up to the sub-header, compared to the air distribution loss that is more in the machine. The Flanges and O-ring gaskets, fixed in the main header pipe lines, are prone to leak more. To study this and correct the same, provide intermediate or feed air receiver to each of the air consuming department. This will help the mill measure separately, the air losses in the transmission (compressor and header) and the losses in the distribution (sub-header and equipment in the department.)

The air receiver ought to have pressure gauge and isolation ball valve, preferably solenoid operated, and receiver water drain valve system. The Mill Project team always reduces its budget to invest in these sub-systems, but the mill's compressed air running cost goes up because of the absence of these field sub-systems useful to condition and monitor the mill, air daily demand and supply air flow at rated pressure with minimum allowable pressure drops. 

Are we seeing compressed air losses in machine usage?

Many mills operate at 7 to 8 Bar band in load and unload settings. However, only 6 to 6.5 Bar is enough for the load and unload pressure settings. Invest in air bottles to each of the compressed air consuming machines. Many mills fix a digital air pressure gauge (it is the machine OEM initiative) and give only minimum pressure required for the machine.

Say, the autoconers can be retrofitted with three inch PPR pipe under the total machine length and this will give 200 litres buffer tank. All the control and working pressure tapping can be taken from this retrofit pipe. Mills think of pressure boosters to satisfy higher pressure demands of machine OEMs. Discuss with OEM how to reduce the machine operating pressure with spare air bottle as buffer.

How to prioritize compressed air losses in leakage

Losses are happening in the compressed air generation, distribution in the usage. In the usage part, the leakage in the machine is more than the machine usage now. Hence the question of arresting the leakage is becoming a priority now. What is the leakage in the machine during OFF time? Measure this first to arrest next.

This is similar to our domestic 1000 litre overhead tank where, 100 litre /hr or (%) water enters the from the top of the tank. 50 litre /hr or (%) is drained silently through the bottom drain plug. And the balance 50 litre /hr (%) only is used for the house. Like that, some mills record more than 50 per cent compressed air leakage.

By arresting leakage losses to the minimum, mills stand to gain now. Returns on investment are around six months only. But keep in mind, no mill can achieve zero leakage. So, the aim should be to contain air leakage to the minimum possible per cent.

How the air consuming machine oem & compressor oems can help now?

The machine OEMS in the other segments have realised the preciousness of compressed air. Please try to keep OUT, the air sub header, FRL, etc input components visible to the user daily. Do not keep the inlet air header under closed door but it must stand out of the machine for easy and timely attendance of air input problems.

Provide a buffer bottle or pipe line so that air supply to the machine individual pneumatic actuation mechanism is not restricted or starved of air. Always give open access to the worker so that he can daily remove the water collected at the machine end water drain valve at the bottom most point. If possible, provide digital air pressure gauge to the machine inlet. Some mills are already planning to put Rotameter type or digital type air flow instant metering.

Provide air intake Delta Pressure gauge outside the compressor hood so that each mill can around 2 per cent KWH on condition monitoring the same. Kindly educate the air consumer on how to keep compressed air useful to the pneumatic machine health.

When installing the machine, give the consumer the best installation possible. The compressor and compressed air inefficiency starts from compressor house. Allow no Tee but only Y pipe connections in the house.

Why is the installation of the compressed air system not professional?

Fig 4. Do's & Don'ts of compressor hot air exhaust ducting

During my energy audit of more than a few hundred industries, I noticed that eight of 10 mills have fixed same size duct to match mouth size, but of longer lengths (Fig 4). The damage is done to the machine right from the installation! They ought to provide the duct double the mouth size so that hot air from the compressor hood may go out. That one-time expense enables the compressor breathe better forever.

Mills buy the latest and efficient compressors or machines. They do not plan to mark a tiny fraction of budget cost towards installation and never give time to commission the same professionally.

I request users to revisit their compressor installation manuals and commissioning reports and check for non-conformance. The mill must have a commissioning report of what kw/cfm has ben achieved as reported by the OEM. Then, the mill must do an FAD test twice a year using the pump-up capacity method.

Many mills are forced to change their compressor air end elements - which cost half of what the compressor costs -- within their life period prematurely because of poor installation and because the post air cooler is getting choked. The latter is bound to happen due to textile micro fluff floating. This situation can only improve if the machine HX suction is oriented towards the outer ambient. If the HX sucks only the machine's hot air, then it functions poorly.

Fig 5 Pre-filter to existing air intake filter and its extension pipe to fresh air entry

Does compressed air metering help?

As energy professionals, we are aware that efficiency of compressed air generation is poor. So, first install a multi-function meter to know daily kWh of compressor during loading, unloading and total units. The relative condition monitoring of the machine input KWH will show the relative compressor consumption deviations.

It will be more accurate to provide compressed air flow meter in the compressed air main header. This will prompt the user to know what each compressor gives per kWh input power, say 3 to 6 cfm. When the OEM says it is 6 cfm/kW, the mill user finds it only around 3 to 5 cfm/kW.

This input kW/output cfm ratio will encourage the mill user to find out healthy parameters in each compressor. The user can also close and open the intermediate air receiver valves in each department to know consumption in each individual department.

So, header flow metering will give a macro view to the management about the efficacy and per cent compressor costing in the mill power break up in units/day. The portable digital flow meter can be used in each machine to routinely measure machine air consumption at the time of switching on and off.

What are zero- and low-cost ways to reduce compressed air consumption?

Give priority to arresting leakage. Outsourced today, leakage detection and correction exercise will give results in three months. It would be a wise decision.

Many mills have stopped one of three running compressors after arresting leakage. When you can hear the compressed air leak in any compressed air pipe line or machine, it means one third, or about 33 per cent of air flow in that airline is leaking. First, arrest audible leaks. Then use an Ultrasonic Leakage Detector to arrest minute leaks.

BEE says, any machine above 10 HP, operated for more than 6,000 hours a year i.e. two shifts a day, needs to fix a kWh meter to assess the machine's productive health. Here we can measure both compressor's air power and tare power now.

Investing in an air receiver can stall other retrofits. These include comforting the compressor and zero air loss compressed air drain valves with pre-fixed Y-type strainer cleanable daily on-line to save the main drain valve. They also include adding the daily cleanable pre-filter to the existing air intake filter, positive cross ventilation inside the compressor hood, load and unload pressure sensor shifting to air receiver and many finer points of daily monitoring that bring down compressed air energy consumption by one third.

Courtesy  :   Shri S. Ashok, BEE Accredited Energy Auditor, Chairman IAEMP Coimbatore