## BELIEVE

Okay, in case you haven’t been around the past year or two, and you have no clue where that simple word/statement comes from, then let me be the first to tell you that Ted Lasso is a great show, and you should check it out. So what does that have to do with EXAIR? Well, I like to think that sometimes the Application Engineers here are a lot like the coaching staff on the show. Sometimes we are strategic, we want to assert our experience and knowledge, and others, we are like Ted where we just ensure the thoughts and ideas you have already had.

That’s the fun part of being an Application Engineer here at EXAIR. I get to speak, chat, or email with both existing customers and potential new customers, resellers, and even catalog houses who all are trying to do one thing, improve a process or help someone out. Recently I was working with a manufacturing company trying to determine how fast they can cool a slab of steel with a Super Air Knife. Now, I by no means have a background in thermo like Russ Bowman, but he was busy preparing for our Spring Webinar to share some knowledge on Compressed Air System Storage. (If you haven’t checked a webinar out, most are available on our website in our knowledge base. ) So, I took the time to try and remember some of the tools I learned while at the University of Cincinnati. Thermodynamics was by far one of the hardest classes for me, The Algebra was always easy, I just always looked at the problems sideways I guess, and worried about too many variables. The truth of it is, if you keep it simple you can generally get somewhere close. so I took that approach. First I looked at what heat load would be generated by the steel slab.

I looked at the basic Heat Transfer equation – Q=c x m x ΔT where:

Q = Heat
c = specific heat capacity
m = mass
ΔT = Change in temperature

I was able to locate the mass of the carbon steel plate with 1/2″ thickness. So I calculated the mass of the sheet. Then looked up the specific heat of the same plate, and took the change in temperature from what the customer stated the plate started at and finished at.

This resulted in a heat load. Then to calculate how much cooling a Super Air Knife could provide I utilized another calculation that gives the BTU constant of a cubic foot of air moving and I did decrease the efficiency of the knife due to some assumptions on space and temperature constraints. The resulting factor was the customer would need 6 Super Air Knives to blow the sheet down as it travels 5 feet per minute on a 60′ long conveyor.

This again had several assumptions and I made that very clear to the customer. To convert the amount of air a Super Air Knife puts out and how much cooling it can use, I did make some clear assumptions on the temperature of their atmosphere and the amount of entrainment then I used a calculation that we adapt for Vortex Tubes and Cabinet coolers to determine what cooling load will be achieved if the air pressure or temperature is less than optimal on one of those products.

In the end, the customer received an educated estimation or calculated answer with listed assumptions, to solve their issue with cooling a steel slab before it is stacked together. I really only used two calculations and manipulated some variables to try and make sense of what I knew and what the customer needed. The best part is, this whole process is backed by our 30-day guarantee on stock products which our 48″ Super Air Knife is. So this customer can take my basic math, use my suggestions, place an order, and test it out in their facility for a factual performance test to then proceed with a permanent solution.

If you would like to discuss any point of use or potential application for compressed air in your facility, please contact an Application Engineer today!

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

## NIOSH Hierarchy of Controls

Last year I hosted a Webinar about the NIOSH Hierarchy of Controls and compressed air safety! You can watch that here on our website!

The hierarchy of controls is a strategy that originates from NIOSH (National Institute for Occupational Safety and Health). NIOSH is the federal agency responsible for conducting research and making recommendations for the prevention of work-related injury and illness. This hierarchy is their recommendation for increasing safety for personnel by taking specific steps and how each step increases safety moving from bottom to top of the pyramid. In this blog I will explain the main elements of the HIERARCHY OF CONTROLS and illustrate how to reach the highest level of control with important compressed air safety standards.

The least effective methods are Administrative Controls and Personal Protective Equipment (PPE). Administrative Controls involve making changes to the way people perform the work and promoting safe practices through training. The training could be related to correct operating procedures, keeping the workplace clean, emergency response to incidents, and personal hygiene practices, such as proper hand washing after handling hazardous materials. PPE is the least effective method because the personnel themselves make the choice to wear them or not wear them in any particular situation. They can be trained on the risks of not using PPE equipment (ear plugs, gloves, respirators, etc.) but we all know it does not always get used. PPE can also become damaged, may be uncomfortable and not used, or used incorrectly.

In the middle range of effectiveness is Engineering Controls. These controls are implemented by design changes to the equipment or process to reduce or eliminate the hazard. Good engineering controls can be very effective in protecting people regardless of the the actions and behaviors of the workers. While higher in initial cost than Administrative controls or PPE, typically operating costs are lower, and a cost saving may be realized in the long run.

The final two, Elimination and Substitution are the most effective but can be the most difficult to integrate into an existing process. If the process is still in the design phase, it may be easier and less expensive to eliminate or substitute the hazard. Elimination of the hazard would be the ultimate and most effective method, either by removing the hazard altogether, or changing the work process so the hazard is no longer part of the process.

EXAIR can help your company follow the Hierarchy of Controls, and eliminate, or substitute the hazards of compressed air use with relative ease.

Engineers can eliminate loud and unsafe pressure nozzles with designs that utilize quiet and intelligent compressed air products such as Air NozzlesAir Knives and Air Amplifiers. Also, unsafe existing products such as air guns, can be substituted with EXAIR engineered solutions that meet the OSHA standards 29 CFR 1910.242(b) and 29 CFR 1910.95(a).

Elimination and Substitution are the most effective methods and should be used whenever possible to reduce or eliminate the hazard and keep people safe in the workplace. EXAIR products can be easily substituted for existing, unsafe compressed air products in many cases. And to avoid the hazard altogether, remember EXAIR when designing products  or processes which require compressed air use for cooling, cleaning, ejection, and more.

If you have questions about the Hierarchy of Controls and safe compressed air usage from any of the 15 different EXAIR Intelligent Compressed Air® Product lines, feel free to contact EXAIR and myself or any of our Application Engineers can help you determine the best solution

Jordan Shouse
Application Engineer

Send me an Email
Find us on the Web

Hierarchy of Controls Image:  used from  Public Domain

## Carburetors and Venturi Tubes: Thank You Giovanni Battista Venturi

I know it has been a little while since I blogged about something with a motor so it should be no surprise that this one ties to something with a combustion chamber. This all starts with an Italian physicist, Giovanni Battista Venturi. His career was as a historian of science and a professor at the University of Modena. He gave Leonardo da Vinci’s creations a different perspective by crediting da Vinci to be a scientist with many of his creations rather than just an amazing artist. He then began to study fluid flow through tubes. This study became known as the Venturi Tube. The first patents in 1888 came to fruition long after Giovanni passed away. So what was this Venturi effect and how does it tie in to carburetors let alone compressed air?

The illustration below showcases the Venturi effect of a fluid within a pipe that has a constriction. The principle states that a fluid’s velocity must increase as it passes through a constricted pipe. As this occurs, the velocity increases while the static pressure decreases. The pressure drop that accompanies the increase in velocity is fundamental to the laws of physics. This is another principle we like to discuss known as Bernoulli’s principle.

Some of the first patents using Venturi’s began to appear in 1888. One of the key inventors for this was Karl Benz who founded Mercedes. This is how the Venturi principle ties into combustion engines for those that do not know the history. This patent is one of many that came out referencing the Venturi principle and carburetors. The carburetors can vary considerably in the complexity of their design. Many of the units all have a pipe that narrows in the center and expands back out, thus causing the pressure to fall and the velocity to increase. Yes, I just described a Venturi, this effect is what causes the fuel to be drawn into the carburetor. The higher velocity on the input (due to this narrowing restriction) results in higher volumes of fuel which results in higher engine rpms. The image below showcases Benz’s first patent using the Venturi.

While carburetors slowly disappear and now can mainly be found in small engines such as weed eaters, lawn mowers, and leaf blowers, the Venturi principle continues to be found in industry and other items. Needless to say, I think Giovanni Battista Venturi would be proud of his findings and understanding how monumental they have been for technological advancements. For this, we will recognize the upcoming day of his passing 199 years ago on April 24, 1822.

Brian Farno
Application Engineer
BrianFarno@exair.com
@EXAIR_BF

1 – Thierry Dugnolle, CC0, Venturi.gif, retrieved via Wikimedia Commons https://upload.wikimedia.org/wikipedia/commons/1/16/Venturi.gif

## Centrifugal Air Compressors: How Do They Work?

Centrifugal air compressors are one example of dynamic style air compressors. The dynamic type of compressors have a continuous flow of air that has its velocity increased in an impeller that is rotating at a higher speed. The kinetic energy of the air is increased due to the increase in velocity and then becomes transformed into pressure energy through the use of a volute chamber, or a diffuser. The volute chamber is a curved funnel that increases in surface are as it approaches the discharge port. This converts the kinetic energy into pressure by allowing the velocity to reduce while the pressure increases. Approximately 1/2 of the energy is developed in the impeller and the other half is developed in the volute chamber or diffuser.

The most common centrifugal air comppressor has between two and four stages in order to generate pressures up to 150 psig. A water cooled inter-cooler and separator is placed between each stage in order to remove condensation and cool the air down prior to being passed on to the next stage. These compressors still have advantages and some disadvantages. The list below showcases just a few.

• Lubricant-free air is generated
• Complete packages up to 1,500 hp
• Initial costs decrease with increase in compressor size
• No special foundations or reinforcements needed