Month: June 2013

As Seen At The County Fair

Published on by Russ BowmanLeave a comment

Have you ever been in a public place and noticed one of your company’s products in full view of everyone passing by? Those of you who work for car manufacturers, soda bottlers, or snack food makers (like my three friends that I had this conversation with recently do) may not think it’s a big deal (my friends indeed didn’t), so you’ll have to forgive those of us who work mainly in industrial or commercial markets when we get excited to see something that came from The Shop, while we’re walking around the County Fair.

Years ago, I worked for an industrial weighing equipment company. Every year, we were asked to provide a scale for the County Auditor’s booth at the fair – people could step on this scale, and get their weight automatically printed out on one of the Auditor’s business cards. It was a neat little setup, and my friends who recognized that it came from my employer would all crack wise about how obviously inaccurate this scale was. Since I was the one who calibrated the scale, using test weights that I was responsible for having certified by the state, I knew that the numbers on those printed cards said a lot more about the availability of deep fried candy bars on the midway, than the intrinsic accuracy of our precision instrument.

When I go to the fair this summer (and I will, and not just for the deep fried candy bars), I’m certain it’ll be hot that day…which means I’ll have my eye out for the cooling stations that are always set up along the midway, providing a fine mist of cooling water. In addition to a brief respite from the summer heat, I’ll also be looking for EXAIR Atomizing Spray Nozzles, as this would be an ideal application for our External Mix Atomizing Spray Nozzles. They provide independent control of the liquid flow rate – which will be determined solely by the liquid supply pressure – and the air used to atomize the spray: varying the air pressure won’t affect the amount of liquid; only the size/shape of the flow pattern.

Depending on what you need to spray, how much (or little) of it you need to disperse, and over what kind of area, we also have highly efficient Internal Mix designs, and, if your liquid isn’t able to be pressurized, we have Siphon Fed Spray Nozzles as well.  We recently added No Drip options to all models as well, to conserve expensive solutions, and/or to prevent inadvertent stains, runs, etc.

They’re all available in a variety of narrow and wide angle, round and flat fan patterns. For more information, feel free to give us a call.

Russ Bowman
Application Engineer
EXAIR Corporation
(513)671-3322 local
(800)923-9247 toll free
(513)671-3363 fax
Web: http://www.exair.com
Blog: http://blog.exair.com/
Twitter: twitter.com/exair_rb
Facebook: http://www.facebook.com/exair

EXAIR Provides Clarity and Benefits of Static Eliminators

Published on by Neal RakerLeave a comment

As we in the Northern Hemisphere are getting ever closer to our summer season, our friends in the Southern Hemisphere are gearing up for winter and the effects that it brings for some production environments. Namely, low humidity causing static problems.

One of our good customers in South Africa needed to get up to speed on some issues regarding EXAIR Static Eliminators and static issues in general. Following is a list of questions and the answers I gave to help them gain a better understanding.

ESD primer

  1. Do the EXAIR Static Eliminators transmit both positive and negative ions?
    Answer: Yes, since they are an AC ionizer, the AC wave form changing polarity 50 – 60 times per second (Hz) AC Wave      causes the ions to be both positive and negative so that either positive or negative charge can be reduced in an application.
  2. What electrostatic field reading (with model 7905 Static Meter) would you classify as being a potentially high static reading?
    Answer: A specific static reading would not necessarily be considered high or low for any given application. What I mean is that you want to gauge a static reading as being high or low depending on whether it actually creates a problem in the production environment. The static meter simply puts a number to it so you can at least have a measurable figure to go by when implementing any sort of static elimination solutions. In practice, this means that for one application a 5kV charge might be extremely high and cause many problems. For another application, 5 kV does not cause any problems at all. So, it is somewhat relative. That being said, the full range of the static meter is +/- 20 kV at 1 inch from target. Between 3 and 5 kV is where you will begin to see problems in industrial applications, although they could possibly start at lower voltages. Just to give you an anecdotal frame of reference, if you have ever been shocked by a door knob when walking through your house in your socks, that is about 8 kV of charge that you give to the door knob or other grounded surface when you touch it.door knob zap
  3.  What polarity static measurement be classed as a static issue? Positive, negative or either?
    Answer: Both polarities of charge can cause problems in applications. Thus, the reason for having an AC ionizer, as mentioned above they can work to reduce either polarity charge.
  4. What is the correct procedure for the cleaning of ionizing bars?
    Answer: We have a very informative video explaining this process that can be reviewed here.
  5. How do distance and input pressure affect the ability of an air operated ionizer to reduce a static charge?
    Answer: The further away an air operated static eliminator is from its target, the longer the time required to reduce the static charge. Also, static will take longer to decay at lower input pressures. Optimum distances for a static eliminator are between 3” and 36” from target. Static reduction will still occur at distances up to about 15 feet away, although at a reduced decay rate.
  6. How does the amount of time in contact between a target material and a static eliminating airflow affect the static charge?
    Answer: The time in contact between an ionized airflow and the intended target is one of the most critical factors when considering how one would set up a static eliminator into an application. Since materials are usually moving by a static eliminator at high rates of speed, one way to increase the time in contact is by strategically mounting the static eliminator to blow onto the target at a very low blowing angle. I will usually say, almost parallel to the material if is something like a flat web or similar where that is possible. If you can visualize a static eliminating airflow as a shadow that appears on a side walk. When the sun is high in the sky, the shadow is very short. When it is lower in the sky, the shadow becomes very long. Without making the analogy too complicated, think of the sun as the static eliminator and the shadow as the ionized airflow and the sidewalk as the target. The lower the angle, the longer the contact time. This is optimized mounting strategy to increase time in contact.

short shadowLong shadow

Neal Raker, Application Engineer
nealraker@exair.com

The Evolution of the Nozzle

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In the beginning, when hearing and energy conservation were not a consideration, simple open pipes were used for blow off operations. These are a waste of compressed air, dangerously loud, and potentially injurious. Federal regulations have since been implemented requiring hearing protection from exposure  to sound levels 90 dBA over a period of  8 hours or greater. It also mandates that if an orifice be dead ended against the skin it would not exhibit more than 30 psi.

safety nozzle

Safety Nozzle

Thirty years ago, EXAIR got its start making a more efficient nozzle that was O.S.H.A. compliant. The design sheltered the main air orifice down in a milled groove. The secondary orifice is an annular opening. This provides two functions. By chance if someone could find a way to block the main orifice, there is a secondary path for air to flow. The annular orifice also develops a tube of air surrounding the high velocity main air flow. This interaction deadens the sound level as well as creating a vacuum to draw in surrounding air.

Air Jet

air jet

The next step in the evolution is an air jet which utilizes the coanda effect which is the phenomenon where high velocity air will adhere to a surface. Compressed air is injected through an annular orifice at sonic velocity. The injected air is directed toward the output and creates a vacuum on the opposite end. This vacuum pulls in large volumes of free air and results in a larger volume of air on to the target. If one end or the other is blocked, flow simply reverses at well below OSHA dead ended pressure requirements.

Air Amplifier

air ampSimilar in design concept but in larger configurations is the air amplifier.  They move massive amounts of air which makes them an ideal solution for cooling, ventilating, and for blow off. Two styles were developed. An adjustable style were the annular orifice can manually be adjusted to control air flow and force. The second design has a fixed flow where the annular orifice is established with a patented shim.

Super Air Nozzle

nozzle

The more recent improvement on the safety nozzle is the Super Air Nozzle. The design concept here is to embed the orifices between fins around the perimeter of the nozzle. This prevents blockage by providing a path fore and aft for air to escape and remain below the OSHA dead end pressure threshold.  The high velocity air also creates a low pressure area drawing in up to 25 times in volume of surrounding ambient air than the volume of compressed air consumed. Sound levels are also greatly reduced.

EXAIR is not done exploring new and improved compressed air products. Product design is customer driven so we welcome your feedback.

Joe Panfalone
Application Engineer
Phone (513) 671-3322
Fax (513) 671-3363
Web: http://www.exair.com
Twitter: http://www.twitter.com/exair_jp
Facebook: http://www.facebook.com/exair