More Force is not Always Better for Cleaning Glass

Glass Annealing Machine with model 110230

A float glass company purchased an EXAIR model 110230 Super Air Knife kit to clean the surface of glass sheets.  The production manager watched the video of the performance of the Super Air Knife, and he was amazed at the efficiency, effectiveness, and safety that they could provide.  (We have many EXAIR Product videos here).  After they received the Super Air Knife, they mounted it after the annealing process to remove any specks of dirt and debris prior to the final visual inspection.  They were getting some false rejections from contamination that remained on the sheets, and they believed that they needed more force to better clean the surface of the glass.

The blowing system was operating at 73 PSIG (5 bar) air pressure, the maximum amount that could be supplied at the machine.  With the dynamics of the Super Air Knife, the blowing force could be increased by changing the shim thickness.  The plant manager contacted me about the characteristics in force and flow by changing from the standard 0.002” (0.05mm) thick shim to the 0.003” (0.08mm) or 0.004” (0.1mm) thick shim.  (These shims are Included in the shim set for aluminum Super Air Knife kits along with a 0.001” (0.025mm) thick shim).  As an Application Engineer at EXAIR, I was inquisitive about the application and wanted to do a “forensic” analysis of the system to generate the best suggestion.  So, I had him send me pictures of their setup.

With non-conductive materials like glass and plastic, static can be a huge issue.  Static forces can easily be generated and will cause dirt and debris to “stick” to a surface.  This attraction is very strong and will make it very difficult to remove.  If the static force can be neutralized, then the contamination can easily be removed from a non-conductive surface.

With this understanding, my initial suggestion for the company above was to remove the static charges from the surface of the glass with an EXAIR Static Eliminator.  With the complimentary design of the Super Air Knife, it is simple to mount an Ionizing Bar directly to the Super Air Knife that they currently installed.  I recommended a model 8030, 30” (762mm) long Gen4 Ionizing Bar, and a model 7960 Power Supply to transform the Super Air Knife into a Gen4 Super Ion Air Knife.  The positive and negative ions that are generated by the Gen4 Ionizing Bar can be carried by the laminar air flow of the Super Air Knife to treat the surface.  This combination can work well to remove static charges up to 20 feet (6m) away.  Once the static is removed, the force of the air stream would easily remove any dust or debris from the glass surface.

Gen4 Super Ion Air Knife

As an added note from the picture above, I recommended a different position for the Super Air Knife, or soon to be Gen4 Super Ion Air Knife to optimize the blowing area.  The glass company had the air knife positioned to blow straight across the surface of the glass.  For proper cleaning and better contact time, I suggested to mount the Super Air Knife with the Ionizing Bar about 6” (152mm) above the surface of the glass and angle it to about 45 degrees.  This would increase the contact angle and allow for a better blowing force to remove all the debris.  By adding the Gen4 Ionizing Bar and adjusting the blowing angle, they were able to reduce the air pressure from 73 PISG (5 bar) to 30 PSIG (2 bar); saving compressed air and reducing false rejections.

Pictures are always helpful in analyzing an application.  With the company above, we were able to optimize their cleaning process and reduce the total amount of compressed air required.  If you find that you need more force to clean a non-conductive surface, EXAIR Static Eliminators will resolve these static problems.  If you would like to discuss your application with an Application Engineer at EXAIR, we can go through the “forensics” analysis for optimization.

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

Absolute Pressure Ratio

This model 1101 Super Air Nozzle requires 14 SCFM @ 80 PSIG. How much air will it consume at 60 PSIG?

Compressed air driven devices are always given a specification for the compressed air flow at a certain pressure.  For example, an EXAIR model 1101 Super Air Nozzle has a specified flow of 14 SCFM at 80 PSIG.  This means that when this nozzle is operated at 80 PSIG, it will require 14 SCFM of compressed air flow.  But what if the force from the nozzle is too high when operated at 80 PSIG and a lower operating pressure is needed?

Thankfully, we can calculate the compressed air flow at a different pressure using the absolute pressure ratio.  The absolute pressure ratio says that for any given change in absolute operating pressure, there will be a proportional change in the air consumption of a device.  So, what is an absolute pressure?

Put simply, an absolute pressure is the value which you would measure on pressure gauge plus the atmospheric pressure (PSIA, or Pounds per Square Inch Atmospheric).  So, our 80 PSIG operating pressure mentioned above is an absolute pressure of 94.5 PSI (80PSIG + 14.5 PSIA).  Similarly, if we wanted to determine the compressed air flow at an operating pressure of 60 PSIG, our absolute pressure would be 74.5 PSI (60 PSIG + 14.5 PSIA).

The absolute pressure ratio is a ratio of the new absolute operating pressure (new PSIG + PSIA) compared to the known absolute operating pressure (known PSIG + PSIA).  For example, when comparing an operating pressure of 60 PSIG to an operating pressure of 80 PSIG, we will end up with the following ratio:

This means that our absolute pressure ratio in this case is 0.7884.  To determine the compressed air flow for the model 1101 Super Air Nozzle at 60 PSIG, we will take this ratio value and multiply it by the known flow value at 80 PSIG.  This will yield the following:

Utilizing this formula allows us to truly compare a compressed air powered device at different operating pressures.  If we did not use the absolute pressures when comparing compressed air devices at differing pressures, our values would be erroneously low, which could yield to improper compressed air system planning and performance.  And, using the absolute pressure ratio allows anyone to make a true comparison of compressed air device performance.  If specifications are given at different pressures, performance data can be misleading.  But, by using the absolute pressure ratio we can make a more exact evaluation of device operation.

If you have a question about your compressed air device and/or how a change in pressure will impact compressed air flow, contact our Application Engineers.  We’ll be happy to help.

Lee Evans
Application Engineer
LeeEvans@EXAIR.com
@EXAIR_LE

No Drip Atomizing Spray Nozzles Improve Pizza Crusts

I like some better than others, but I don’t believe I’ve ever had bad pizza. That’s why I was pretty excited when I got to talk to a caller from a popular pre-packaged pizza crust maker. When these crusts leave their oven, they spray a coating of seasoned oil on them. This not only flavors, but preserves the quality from the time they make & package them to the time I celebrate life with a tasty slice, right out of my oven.

They were using inexpensive liquid-only nozzles that led to an inconsistent application of the oil…sometimes too much; other times, too little. And, it was always spraying, even in between the individual crusts as they came down the conveyor, leading to wasted oil that had to be cleaned up later.

They were already familiar with our Super Air Nozzles, as they had several Model HP1125SS 2″ High Power Flat Super Air Nozzles in use for blowing off the packages prior to labeling, so the caller asked if we might have a solution for the oil too.

We did.

After considering the size of the crust and the distance at which they needed to install the nozzle, they decided to try a Model AF2010SS Internal Mix Flat Fan Pattern No-Drip Atomizing Spray Nozzle. This applies a consistent and even coating of oil, and, by feeding a signal from the oven controls into a solenoid valve in the compressed air supply line, they’ve eliminated the excess spray, leading to savings in material cost and cleanup time.

EXAIR No Drip Atomizing Spray Nozzles…controllable, fine mist on demand, with no mess.

If you’d like to know more about how EXAIR Atomizing Spray Nozzles can save you time, mess, and liquid, give me a call.

Russ Bowman
Application Engineer
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Intelligent Compressed Air: What is an Air Compressor?

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Example of the supply side of a compressed air system

One thing that is found in virtually every industrial environment is an air compressor. Some uses for the compressed air generated are: powering pneumatic tools, packaging, automation equipment, conveyors, controls systems, and various others. Pneumatic tools are favored because they tend to be smaller and more lightweight than electric tools, offer infinitely variable speed and torque, and can be safer than the hazards associated with electrical devices. In order to power these devices, compressed air must be generated.

types of compressors

There are two main categories of air compressors: positive-displacement and dynamic. In a positive-displacement type, a given quantity of air is trapped in a compression chamber. The volume of which it occupies is mechanically reduced (squished), causing a corresponding rise in pressure. In a dynamic compressor, velocity energy is imparted to continuously flowing air by a means of impellers rotating at a very high speed. The velocity energy is then converted into pressure energy.

Of the positive-displacement variety they are broken down further into two more categories: reciprocating and rotary. A reciprocating compressor works like a bicycle pump. A piston reduces the volume occupied by the air or gas, compressing it into a higher pressure. There are two types of reciprocating compressors, single or double-acting. Single-acting compressors are the most common and are available up to 30HP at 200 psig. Their small size and weight allow them to be installed near the point of use and avoid lengthy piping runs. These are the types of compressors that would be commonly found in your garage. The double-acting reciprocating compressor is much like its single-acting brethren, only it uses both sides of the piston and cylinder for air compression. This doubles the capacity of the compressor for a given cylinder size. They are much more efficient than single-acting compressors, but are more expensive and do require a more specialized installation and maintenance.

Rotary compressors are available in lubricant-injected or lubicrant-free varieties. These types of compressors use two inter-meshing rotors that have an inlet port at one end and a discharge port at the other. Air flows through the inlet port and is trapped between the lobes and the stator. As the rotation continues, the point intermeshing begins to move along the length of the rotors. This reduces the space that is occupied by the air, resulting in an increase in pressure. In the lubricant-injected compressors, the compression chamber is lubricated between the intermeshing rotors and bearings. This takes away the heat of compression and also acts as a seal. In the lubricant-free varieties, the intermeshing rotors have very tight tolerances and are not allowed to touch. Since there is no fluid to remove the heat of compression, they typically have two stages of compression with an intercooler between and an after cooler after the second stage. Lubricant-free compressors are beneficial as they supply clean, oil-free compressed air. They are, however, more expensive and less efficient to operate than the lubricant-injected variety.

On the other side of the coin, we have the dynamic compressors. These are comprised of two main categories: axial and centrifugal. These types of compressors raise the pressure of air or gas by imparting velocity energy and converting it to pressure energy. In a centrifugal air compressor, air continuously flows and is accelerated by an impeller. This impeller can rotate at speeds that exceed 50,000 rpm. Centrifugal air compressors are generally much larger and can accommodate flow ranges of 500-100,000 CFM. They also provide lubricant-free air.

Axial compressors are used for situations that require lower pressure but high flow rates. They do not change the direction of the gas, it enters and exits the compressor in an axial direction. It is accelerated and then diffused which creates the increase in pressure. A common application that would be served by this type of compressor is to compress the air intake of gas turbines. They have a relatively high peak efficiency, however their large overall size and weight as well as the high starting power requirements pose some disadvantages.

Just as you can find a wide variety of makes and models of automobiles, the same can be said for air compressors. The size, type, and features will be dictated by the types of applications that you’ll be needing the compressed air for in your facility. A quick chat with your local air compressor supplier will help you to determine which type is most suitable for you.

Of course, any of these types of compressors can be used to supply air to your engineered Intelligent Compressed Air Products. If you have an application in your facility that could benefit from an engineered solution, give us a call. An Application Engineer would be happy to discuss your options with you and see to it that you’re getting the most out of your compressed air!

Tyler Daniel
Application Engineer
E-mail: TylerDaniel@exair.com
Twitter: @EXAIR_TD

 

Images Courtesy of  the Compressed Air Challenge and thomasjackson1345 Creative Commons.

Compressed Air Nozzles – Engineered vs. Commercial vs. Homemade

In the world of compressed air blow off solutions, there are a number of options which customers must consider.  Should the plant maintenance personnel configure something on-site?  Is there a low-cost option available from a catalog warehouse?  Or, is there an engineered solution available – and if there is, what does this even mean?

Blowoff comparison

Ultimately, the exercise in comparing these options will help select the option best for the application and best for the company.  In order to make these comparisons, we will consider each option based on the following attributes:  Force, sound level, safety, efficiency, repeatability, and cost.  These are the factors which impact the ability to perform as needed in the application, and effect the bottom line of the company

Force

How much force do you need in your application?

Blow off applications require a certain amount of force in order to perform the desired task.  If the blow off is in a bottling line, for example, we will aim for a lesser force than if blowing off an engine block.  But, no matter the application need, we will want to consider the ability of the solution to provide a high force, high impact blow off.  Homemade and commercially mass-produced nozzles produce low-to-mid level forces, which translates to a need for more compressed air to complete a task.  Engineered nozzles produce high forces, minimizing compressed air use.

Sound level

Have you ever been to a concert and felt your hearing reduced when you left?  This can be the case for personnel in industrial environments with unregulated noise levels.  Homemade or non-engineered blow off solutions carry the risk of increased sound levels which are outside of the acceptable noise level limits.  EXAIR engineered nozzles, however, are designed to minimize sound level for quiet operation and continual use.

Safety

All EXAIR products meet or exceed OSHA Standard 29 CFR 1910.242(b)

Workplace safety is a serious matter for everyone from shop floor personnel to executive management.  Whether you’re working with or near a compressed air operated device, or your making decisions for your company which have to do with the compressed air system, safety is undoubtedly a priority.  Unfortunately, homemade and commercially available nozzles normally fail to meet OSHA standards for dead-end pressure requirements (OSHA Standard 29 CFR 1910.242(b)).  This means that these solutions can pose a risk of forcing compressed air through the skin, resulting in an embolism which can cause severe harm or even death.

EXAIR nozzles, however, are designed to NEVER exceed dead-end pressure limits and to provide an escape path for airflow in the even the nozzle is blocked.  This safety aspect is inherent in ALL EXAIR designs, thereby adding safety to an application when an EXAIR product is installed.

Efficiency

EXAIR Super Air Nozzle entrainment

Compressed air is the most expensive utility in any facility.  Energy enters as an electrical source and is converted into compressed air through a compressor where up to 2/3 of this energy is lost as heat.  The resulting 1/3 of converted energy is then piped throughout a facility as compressed air, where up to 1/3 of the air is lost to leaks.  With this in mind, maximizing the efficiency of a nozzle solution becomes imperative.  A homemade solution or commercial nozzle does not maximize the use of the compressed air.  The result is a need to increase flow or increase pressure, both of which result in higher energy costs.

EXAIR nozzles are designed for maximum force per CFM.  This means that any of our nozzles will produce the highest force at the lowest possible compressed air consumption.  This, in turn, reduces demand on the compressed air system and allows for a lower energy requirement.  Less energy demand means less energy costs, which goes straight to the bottom line of your company.

Repeatability

The EXAIR family of nozzles

When installing a nozzle solution, it is important to have the same force and flow from each unit.  If a solution needs to be replicated, balanced, or adjusted in any way, having various forces and flows from a homemade setup will induce difficulty and could make changes impossible.  Line speed or volume increases may not be possible due to variance in the output flow and forces from homemade setups, but an engineered solution will produce the same output every time.  This means you can adjust the nozzles as needed to achieve the perfect solution in your application.

Cost

For many customers and businesses, the most important aspect of any solution comes down to cost.  Will the solution work?  And, how much does it cost?  When it comes to a homemade or commercial blow off solution, it may or may not work, and it will have a low purchase cost.  But, the purchase price isn’t the whole story when working with compressed air.  The real cost of an item is in the operation and use.  So, while a homemade solution will be cheap to make and install, it will be EXPOENTIALLY more expensive to operate when compared to an engineered solution.  An excellent example is shown above.  An open copper tube is compared to an EXAIR model 1102 Mini Super Air Nozzle.  The copper tube cost only a few dollars to install, many times less than the EXAIR nozzle, but it costs almost two THOUSAND dollars more to operate in a year.  Translation:  Install a cheap blow off solution and pay for it in utility costs.

EXAIR nozzles and blow off solutions are engineered for maximum force, lowest possible noise level, OSHA safety compliance, maximum efficiency, and maximum repeatability.  These factors allow for options which not only solve application problems, but also do so with the lowest total cost possible.  If you have an application in need of a blow off solution, feel free to contact our Application Engineers.  We’ll be happy to help.  And, if your curious about the benefit of our products in your application, consider our Efficiency Lab.  We will test your existing setup next to our recommended EXAIR solution and provide the impact to your bottom line.

Lee Evans
Application Engineer
LeeEvans@EXAIR.com
@EXAIR_LE

High Temperature Vortex Tube for Sensor Cooling

Last year I worked with a power company that was having issues with Position Feedback Sensors overheating causing erroneous readings and early failures.  The sensors were located above a steam turbine, and the ambient temperatures reached 128°F with spikes to 140-150°F.  The customer had called in looking for a way to keep the sensors cool, using minimal compressed air, and in a robust package.  After reviewing the details, we recommended the High Temperature Vortex Tube, model HT3210.  While using just 10 SCFM of 100 PSIG compressed air, the HT3210 provides 8 SCFM of cold air at a temperature drop of 54°F from the supply air temperature.  Bathing the sensor with this cool air keeps prevents it from heating up and has eliminated the bad readings and prevented the early failures.

The customer recently implemented the same fix for another set of sensors.

Plant Photo
Power Generation Process, with (3) Position Feedback Sensors
Sensor
Position Feedback Sensor

The High Temperature Vortex Tube is a special Vortex Tube offering from EXAIR that utilizes a brass generator and hi-temp seal for use in ambient temperatures up to 200°F.  Simply supply clean, dry compressed air, and get cold air starting at 50-54°F lower than the supply air temperature.  With sizes ranging from 2 to 150 SCFM, there is a Vortex Tube that will meet most applications.

Vortex tube
High Temperature Vortex Tube

If you have questions about the Vortex Tubes, or would like to talk about any of the EXAIR Intelligent Compressed Air® Products, feel free to contact EXAIR and myself or one of our Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

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Cost Savings from Replacing a Drilled Pipe with a Super Air Knife

A few months ago, my counterpart Brian Bergmann wrote a blog providing a detailed explanation of ROI or Return on Investment. Today, I would like to take this information and apply it to a common situation we deal with regularly here at EXAIR – replacing drilled pipe with our Super Air Knife.

Drilled pipe – easy to make but extremely wasteful

Sections of pipe with drilled holes across the length are very common as they are made of relatively inexpensive materials and simple to make.  Where the cost begins to add up is on the operation side as these types of homemade blowoffs waste a ton of compressed air, making them expensive to operate.

For comparison, lets look at a 12″ section of pipe with (23) 1/16″ diameter drilled holes. According to the chart below, each hole will flow 3.8 SCFM @ 80 PSIG for a total of 87.4 SCFM.

With an average cost of $ 0.25 per every 1,000 SCF used (based on $ 0.08/kWh), it would cost $ 1.31 to operate this blowoff for 1 hour. (87.4 SCFM x 60 minutes x $ 0.25 / 1,000)

Super Air Knife – Available from 3″ up to 108″ in aluminum, 303ss and 316ss

Now let’s take a look at replacing the drilled pipe with our 12″ Super Air Knife. A 12″ Super Air Knife will consume 34.8 SCFM (2.9 SCFM per inch) when operated at 80 PSIG. Using the same figure of $ 0.25 per every 1,000 SCF used, it would cost $ 0.52 / hr. to operate this knife. (34.8 SCFM x 60 minutes x $ 0.25 / 1,000)

Now that we know the operating costs, we can make a better comparison between the 2 products.

Drilled pipe operating costs:
$ 1.31 per hour
$ 10.48 per day (8 hours)

12″ Super Air Knife costs:
$ 0.52 per hour
$ 4.16 per day (8 hours)

Cost Savings:
$ 10.48 per day (drilled pipe) –  $ 4.16 per day (Super Air Knife) = $ 6.32 savings per day

A 12″ aluminum Super Air Knife carries a LIST price of $ 297.00. If we take $ 297.00 divided by $ 6.32 (saving per day), we get a ROI of only 47 days.

As you can see, it is quite beneficial to consider ALL of the parameters when looking at a process or application, rather than just the “upfront” details. What seems like a simple and easy fix, can actually be quite  wasteful when it comes to the true cost of ownership.

If you are using similar devices in your plant and would like to see how an EXAIR Intelligent Compressed Air Product can help make the process operate more efficiently, contact an application engineer for assistance.

Justin Nicholl
Application Engineer
justinnicholl@exair.com
@EXAIR_JN