Tag: distribution

Compressed Air Distribution System, Keeping Pressure Drop to a Minimum

Published on by johnball2014Leave a comment

Compressed air is used to operate pneumatic systems within a facility, and it can be separated into three categories; the supply side, the demand side, and the distribution system.  The supply side is the air compressor, after-cooler, dryer, and receiver tank that produce and treat the compressed air.  They are generally located in a compressor room somewhere in the corner of the plant.  The demand side is the collection of devices that will use that compressed air to do “work”.  These pneumatic components are generally scattered throughout the facility.  To connect the supply side to the demand side, a compressed air distribution system is required.  Distribution systems are pipes which carry the compressed air from the compressor to the pneumatic devices.  For a sound compressed air system, the three sections have to work together to make an effective and efficient system.

An analogy that I like to use is to compare the compressed air system to an electrical system.  The air compressor would be considered the voltage source, and the pneumatic devices would be marked as light bulbs.  To connect the light bulbs to the voltage source, electrical wires are needed which will represent the distribution system.  If the gauge of the wire is too small to supply the light bulbs, the wire will heat up and a voltage drop will occur.  This heat is given off as wasted energy, and the light bulbs will be dim.  The same thing happens within a compressed air system.  If the piping size is too small, a pressure drop will occur.  This is also wasted energy.  In both types of systems, wasted energy is wasted money.  One of the largest systematic problems with compressed air systems is pressure drop.  If too large of a pressure loss occurs, the pneumatic equipment will not have enough power to operate effectively and efficiently.  As shown in the illustration below, you can see how the pressure decreases from the supply side to the demand side.  With a properly designed distribution system, energy can be saved; and, in referencing my analogy above, it will keep the lights on.

Pressure Drop Chart

To optimize the compressed air system, we need to reduce the amount of wasted energy.  This can be caused from leaks or pressure drop.   Leaks can be hidden and are typically located at connections within the distribution system.  In a poorly maintained system, a study found that 30% of the compressor capacity is lost through air leaks on average.  Even though leaks are the “silent killer” to a compressed air system, they can be found with the Ultrasonic Leak Detector. 

Pressure drop is more of a wide range issue.  It is based on restrictions, obstructions, and piping surface.  Out of these, restrictions are the most common types of pressure drops. The air flow is forced into small areas, causing high velocities.  The high velocity creates turbulent flow which increases the losses in air pressure.  Flow within the pipe is directly related to the velocity times the square of the diameter.  So, if you cut the I.D. of the pipe by one-half, the flow rating will be reduced by 25% of the original rating.  Restriction type of pressure drop can be found in different forms like small diameter pipes or tubing; restrictive fittings like quick disconnects and needle valves, and undersized filters, regulators and valves.

As a rule, air velocities will determine the correct pipe size for the distribution system.  It is beneficial to oversize the pipe to accommodate for any expansions in the future.  For header pipes, the velocities should not be more than 20 feet/sec (6 meter/sec).  For the distribution lines, the velocities should not exceed 30 feet/sec (9 meter/sec).  In following these simple rules, the distribution system can effectively supply the necessary compressed air from the supply side to the demand side.

To have a properly designed distribution system, the pressure drop should be less than 10% from the reservoir tank to the point-of-use.  By following the tips above, you can have the supply side, demand side, and distribution system working at peak efficiency.  If you would like to reduce waste even more, EXAIR offers a variety of efficient, safe, and effective compressed air products to fit within the demand side.  This will include the EXAIR Super Air Knives, Super Air Nozzles, and Safety Air Guns.  This would be the pneumatic equivalent of changing those incandescent light bulbs into LED light bulbs.  If you wish to go further in optimizing your system, an Application Engineer at EXAIR will be happy to help you. 

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb

Photo:  Lightbulb by qimono.  Pixabay Licence

Pressure Drop Chart by Compressed Air Challenge Organization.

Compressed Air Pipe

Compressed Air and Pneumatic Systems

Published on by johnball2014Leave a comment

Compressed Air Pipe

Compressed air is used to operate pneumatic systems in a facility, and it can be segregated into three main sections; the supply side, the demand side, and the distribution system.  The supply side is the air compressor, after-cooler, dryer, and receiver tank that produce and treat the compressed air.  They are generally found in a compressor room.  The demand side is a collection of devices that will use the compressed air to do “work”.  These pneumatic components are generally scattered throughout the facility.  To connect the supply side to the demand side, a distribution system is required.  Distribution systems are pipes or tubes which carry compressed air from the air compressor to the pneumatic devices.  The three sections have to work together to make an effective and efficient system.

Compressed air is a clean utility that is used in many different ways, and it is much safer than electrical or hydraulic systems.  But most people think that compressed air is free, and it is most certainly not.  Because of the cost, compressed air is considered to be a fourth utility in manufacturing plants.  For an electrical motor to reduce a volume of air by compressing it, it takes roughly 1 horsepower (746 watts) to compress 4 cubic feet (113L) of air every minute to 125 PSI (8.5 bar).  With almost every manufacturing plant in the world utilizing air compressors larger than 1 horsepower, the amount of energy needed is extraordinary.

Let’s determine the energy cost to operate an air compressor by Equation 1:

Equation 1:

Cost = hp * 0.746 * hours * rate / (motor efficiency)

where:

Cost – US$

hp – horsepower of motor

0.746 – conversion KW/hp

hours – running time

rate – cost for electricity, US$/KWh

motor efficiency – average for an electric motor is 95%.

As an example, a manufacturing plant operates a 100 HP air compressor in their facility.  The cycle time for the air compressor is roughly 60%.  To calculate the hours of running time per year, I used 250 days/year at 16 hours/day.  So operating hours equal 250 * 16 * 0.60 = 2,400 hours per year.  The electrical rate for this facility is $0.10/KWh. With these factors, the annual cost to run the air compressor can be calculated by Equation 1:

Cost = 100hp * 0.746 KW/hp * 2,400hr * $0.10/KWh / 0.95 = $18,846 per year in electrical costs.

Filters and Regulator

If we look at the point-of-use or demand side, the compressed air is generally conditioned to be used to run and control the pneumatic system.  The basic units include filters, regulators, and lubricators.  The filters are used to remove any oil, water, vapor, and pipe scale to keep your pneumatic system clean.  They fall into different types and categories depending on the cleanliness level required.

Filter Separators are more of a coarse filtration which will capture liquid water, oil, and particulate.  The Oil Removal Filters are more of a fine filtration which can capture particles down to 0.03 micron.  They are also designed to “coalesce” the small liquid particles into larger droplets for gravity removal.  One other group is for removing oil vapor and smell.  This type of filter uses activated charcoal to adsorb the vapor for food and pharmaceutical industries.  Filters should be placed upstream of regulators.

Pressure Regulators change the pressure downstream for safety and control.  Pneumatic devices need both flow and pressure to work correctly.  The lubricator, which is placed after the Regulator, helps to add clean oil in a compressed air line.  Air tools, cylinders, and valves use the oil to keep seals from wearing with dynamic functions.  Once the compressed air is “ready” for use, then it is ready to do many applications.

For EXAIR, we manufacture products that use the compressed air safely, efficiently, and effectively.  EXAIR likes to use the 5-C’s; Coat, Clean, Cool, Convey and Conserve.  We have products that can do each part with 16 different product lines.  EXAIR has been manufacturing Intelligent Compressed Air Products since 1983.  Compressed air is an expensive system to operate pneumatic systems; but, with EXAIR products, you can save yourself much money.  If you need alternative ways to decrease electrical cost, improve safety, and increase productivity when using compressed air, an Application Engineer at EXAIR will be happy to help you.

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb

Pressure Profile: Where to Measure Your Air Pressure

Published on by Brian FarnoLeave a comment

Generic Layout drawing of compressed air piping system.

In order to fully understand how efficient your compressed air system may be, you will need to generate a system pressure profile at some point.   This is a list or diagram of what pressures you have in your compressed air system at specific locations, as well as the pressure required by all the demand devices on your compressed air system.

One of the reasons for the pressure profile is that you may have an application that is far away from the compressor but also highly dependent on a specific operating pressure.   You may also find an application that, due to pressure losses within the system, causes an artificially high pressure demand.

The list below gives the critical points for measuring your compressed air system profile.

  1. At the air compressor discharge. (If using multiple compressors, measure at each.)
  2. If dryers of any type are being used after the compressor measure downstream from the dryer.
  3. Downstream of each filter. (If a particulate filter and oil removal filter are being used it is best to measure downstream of each individual device.   This is to tell when you have more than a 5 psig pressure drop or a clogged filter.)
  4. After each intermediate storage device, such as receiver tanks.
  5. At the point just before the main line from your compressor room branches off to distribution.
  6. The furthest point of each header line you have installed.
  7. On both sides of every filter/regulator units that are at high pressure point of use applications.

To give you an idea of why it is so important to measure these locations, take a look at the blogs we have posted on pressure drop. (Link Here)  As you can tell by the list of blogs that comes up, pressure drop through piping can really cause a lot of wasted energy in your compressed air system.   If you can get a good base line measurement by utilizing a pressure profile then you can start the process to optimizing your compressed air system.

6 steps
The EXAIR Six Steps To Optimizing Your Compressed Air System.

 

If you would like to discuss this or any of the other 6 steps to compressed air optimization, feel free to contact us.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF