Viscosity – Why it Matters

EXAIR has been manufacturing Intelligent Compressed Air Products since 1983.  We work every day with air properties, such as compressed air pressures and flow rates, when evaluating product performance to provide a solution to a customer problem. We also need to be versed on a certain liquid property, viscosity, as it relates to the operation of (2) of the EXAIR product families, the Atomizing Spray Nozzles and the Industrial Housekeeping liquid vacuums (Reversible Drum Vac and Chip Trapper).

Viscosity is often referred to the thickness of a fluid.  A common example would be water and honey.  Water is a low viscosity fluid, while honey is a high viscosity material.

Dynamic, Shear, or Absolute Viscosity is a measure of the resistance to shearing flow.  If you think of 2 plates (see below) with the bottom one stationary and the top one moving horizontally, and with a fluid between them – this illustrates Absolute Viscosity. When the top plate moves to the right, there will be induced multiple horizontal layers of the fluid, each moving at different speeds (the fluid will be at rest at the bottom, and the top layer will move with the top plate.) The friction generated between the layers will give rise to a force resisting this motion.  The force is proportional to the speed and area of the plate and inversely proportional to the distance between the plates.Capture

In simplest terms, viscosity is the ratio of the shear stress, τ,  to the velocity gradient du/dy.  Of concern to us, it takes more force to cause a very viscous (thick like honey) fluid flow.

Centipoise, cP,  is the common unit of measure for viscosity, and 1 cP is equal to 0.01 g/cm/s.

Water has a viscosity of 1 cP at room temperature and honey ranges from 2,000-10,000 cP.

How does all this relate to EXAIR? It relates to EXAIR because we engineer products to specifically move and use liquids. There are limitations to the viscosity each of these products can handle and still perform well.

The EXAIR Atomizing Spray Nozzles can be used with liquids up to 800 cP. The Internal Mix type nozzles can be used on liquids up to 300 cP. The External Mix nozzles can be used with liquids over 300 cP and up to 800 cP.  Lastly, the Siphon Fed models are good to 200 cP, and do not require a pressure source for the liquid. Each nozzle type will atomize the fluid and provide a very small droplet size, which is ideal for washing,  rinsing, coating, cooling and other applications. Exceeding the cP each of these nozzles are designed to use will result in larger droplet sizes and a more inconsistent fluid flow, which may impact your process.

atomizing nozzle

Atomizing Spray Nozzle

The other EXAIR product family where viscosity is important, is the Industrial Housekeeping Products, especially the High Lift Reversible Drum Vac and High Lift Chip Trapper.  They are capable of moving liquids with viscosities of up to 1400 cP through 20′ of hose.  Simply provide compressed air and turn any closed head drum into a high powered liquid vacuum. Great for coolant, hydraulic oils, waster water, and many other fluids. For these products, as the cP increases, so does the time it will take to move the liquids into or out of the drum.

HLRDVpr_openpit_3mbcmyk (2)

High Lift Reversible Drum Vac

To discuss your fluid viscosity and how an EXAIR Intelligent Compressed Air Product can make your process better, feel free to contact EXAIR and myself or one of our other Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

Send me an email
Find us on the Web
Like us on Facebook
Twitter: @EXAIR_BB

Will It Spray?

Video showing the intended use of EXAIR Atomizing Nozzles, illustrated with a green spray pattern.

 

One of the common questions we receive with regards to our Atomizing Spray Nozzles, is whether they will spray a specific liquid.  Most of the time this is a simple answer, found by referencing the viscosity of the liquid and the viscosity range of the specific atomizing nozzle in question.  But, sometimes the viscosity of a fluid isn’t readily available and the best path forward is testing of the specific fluid or application.

Such was the case with the videos above and below.  This application was to spray a specific mixture comprised of catnip biomass onto materials as they pass along a conveyor.  There was no specific flow rate required, we simply needed to spray a specific width at a specific distance away from the product.

The video above shows the desired spray pattern from the nozzles, something with a wide angle and flatpattern, and the video below shows the most suitable solution we found in testing at EXAIR.

The suitable nozzle in this application was our model AD2010SS, an internal mix nozzle with deflected flat fan spraying pattern and a patented technology to prevent liquid flow after compressed air to the nozzle is turned off.  This nozzle provided the right solution for this application, and shipped from stock on the same day we received the order.

Fast forward a few weeks and this same application found benefit from an Electronic Flow Controller (EFC) model 9057.  The EFC allows for sensor-based control of compressed air flow, and thereby control of liquid flow to the AD2010SS nozzles.  This prevents operation of the nozzles when there is no need to spray the liquid.

The discussion, testing, and implementation of this solution are an excellent example of the engineering support available behind EXAIR products.  We really do help our customers find solutions, and if there is an unknown in an application we’re willing to find the answers together.

Lee Evans
Application Engineer
LeeEvans@EXAIR.com
@EXAIR_LE

EXAIR Atomizing Spray Nozzles Make It Nice & Foggy In Greenhouses

Fog. Nobody likes driving in it. It’s downright perilous to sailing vessels on the open water, but especially those near the shore, or other watercraft. Flights get delayed or cancelled, stranding travelers in airport terminals far from home, and keeping many from pressing matters that necessitated the speed of an airline flight in the first place.  Oh, and it’s ALWAYS where the bad guy is hiding in the movies.  You can tell by the ominous low-string music that starts playing right before things get real nefarious.

You know who LIKES fog, though?  Greenhouse operators.  Their plants get plenty of water to sustain their growth from the well-irrigated soil, but the leaves & petals can wither and get discolored if the humidity isn’t kept at a high level.

The same is true for the parts of a greenhouse that folks don’t see when they’re selecting the annuals to plant on the next nice spring weekend (which we should be coming up on quite soon here!) – like the seed germination chambers.  I had the pleasure of helping a greenhouse operator recently, who needed to replace some old, and malfunctioning, nozzles in one of their germination chambers.  They were interested in the extremely fine mist that our Atomizing Spray Nozzles produce.  After some experimentation with a couple of different flow rates & patterns, they determined that the Model AW1020SS (Wide Angle Round Pattern, Internal Mix) Atomizing Spray Nozzles provided optimal results.

The fine, atomized mist (left) produced by the EXAIR AW1020SS (right) optimizes the seed germination in this chamber.

The fine, atomized mist (left) produced by the EXAIR AW1020SS (right) optimizes the seed germination in this chamber.

As the fogging systems in their other chambers start to fail, they’ve been replacing them with the AW1020SS’.  We shipped them two earlier this week.

With (90) distinct models to choose from, we’ve got the solution to your liquid spraying application.

EXAIR Atomizing Spray Nozzles offer an incredibly wide range of flow rates, patterns, and adjustability to suit most any application that requires a fine liquid mist.  If you’d like to find out more, give me a call.

Russ Bowman
Application Engineer
Find us on the Web
Follow me on Twitter
Like us on Facebook

Bench Testing with Blowoff Kits

Last week, a customer connected with us online via the chat option.  He explained that he was working on a project to remove dust from parts on a table conveyor, situated in a 3 x 5 array. He had purchased the EXAIR Blowoff Kits model 1909SS and model 1910 and had been able to bench test and develop a blowoff system that was successful.  He was ready to scale the up design and procure a set of nozzles and swivels that would work in the automated process.

1909SS Blowoff Kit

Model 1909SS – Stainless Steel Blowoff Kit

blostation

Model 1910 – Instant Blowoff Station

 

The Blowoff Kits such as the Model 1909SS offer an easy way to explore the various nozzle types that EXAIR offers and to test the performance of each for Force, Flow and Sound Levels in your process or test environment.  Each nozzle will have particular traits, and identifying the one that most perfectly matches all your criteria can be done.

The Model 1909SS Blowoff Kit contains (7) different nozzles, all with stainless steel construction.  Included are (4) sizes of the Super Air Nozzle (10, 14, 35 and 60 SCFM capacities), the Micro Air Nozzle, the Adjustable Air Nozzle, and lastly, the 2″ Flat Super Air Nozzle.  A similar Blowoff Kit, model 1909, is available with materials of construction of zinc aluminum alloy, aluminum, and brass.

We have put together a detailed review of blowoff applications, available in the Third Edition of the Air Nozzles Blowoff Guide.  Inside, you can find the technical specifications of all of the Nozzles, Blowoff Kits, Flexible Stay Set Hoses, and Safety Air Guns, that might be of interest to you and your application.

blowoff guide

To Request a copy of the EXAIR Blowoff Guide click here

To discuss your application and how the EXAIR Nozzle and Jets can benefit your process, feel free to contact EXAIR and myself or one of our other Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

Send me an email
Find us on the Web
Like us on Facebook
Twitter: @EXAIR_BB

 

Siphon Fed Atomizing Nozzle Improves Roll Forming Process

Last week I worked with a gutter manufacturer who was looking for a way to spray a light coating of vanishing oil on the rollers of a forming machine. Roll forming is commonly used when needing to maintain a constant and consistent shape or feature across the length of the part. In this particular case, a sheet of aluminum, used as a cover for the gutter, is fed into the machine where it passes over a series of dyes that bends “ribs” and punches small holes into the part to keep leaves or debris from settling on top, while allowing the rainwater to pass through the holes and into the gutter.

They were needing to apply the oil to the rollers because they were starting to see some irregularities in hole size as well as some deformities to the shape of the ribs due to heat being generated during the forming process. The customer was interested in using some type of atomizing spray nozzle in the hopes that providing an atomized mist of liquid may provide for a faster evaporation of the oil so there wasn’t much residue left on the part before packaging.

After further discussing the details, they advised that they were going to have the oil in a container about 12″ below the machine but didn’t have a way to pressurize or pump the liquid to the nozzle. Once again, EXAIR has the perfect solution with our 1/4 NPT Siphon Fed Atomizing Nozzles. These nozzles are the ideal solution where pressurized liquid isn’t available as they use the compressed air to the draw the liquid into the nozzle, up to 36″ of suction height, and mix it internally to produce a mist of atomized liquid spray. For this particular application, the Model # SR1010SS was a good solution as it provides a low flow rate of only 0.8 GPH and a tight spray pattern to focus right at the rollers to avoid any waste or overspray.

sr1010ss

Model # SR1010SS Siphon Fed Round Pattern Atomizing Spray Nozzle – 303ss construction, fully adjustable flow rate

EXAIR offers an extensive range of Atomizing Nozzles that can be used for light coating applications, like above, or for wider coverage areas or higher flow rates. For help selecting the best option to fit your needs, contact one of our application engineers for assistance.

Justin Nicholl
Application Engineer
justinnicholl@exair.com
@EXAIR_JN

Atomizing Nozzles Create Fog for Wet Room Testing

Recently, I was working with a customer that has purchased several of the EXAIR Atomizing Spray Nozzles, specifically the model Aw5020SS.  The customer had another project coming up and needed two more nozzles. I inquired about the application and we discussed at length the way the nozzles are being used.

When a concrete road is being poured, several sample forms are poured during the process. The local Department of Transportation takes the samples and cures them in a wet room for 30 days, and then performs tensile testing, to confirm the concrete meets the strength requirements.  The wet room must be kept at 23°C (73.4°F) and 100% Humidity during this time frame.  The EXAIR model AW5020SS Atomizing Nozzles are used to provide the moisture that ensures the room humidity conditions are met and maintained.  Because the droplets are very fine, the effect of a fog is achieved, with the water droplets suspended in the air, keeping the humidity at 100%.

Atomizing spray nozzles are capable of producing very fine droplet sizes.  A typical rain drop is 6000 microns in diameter, standard liquid nozzles produce droplets ranging from 300-4000 microns.  The EXAIR Atomizing Nozzles produce droplets from 20-100 microns!

AW5010pr800.jpg

Model AW5020SS

Droplet  sizes can be adjusted by varying either the liquid pressure or air pressure. Increasing the air or decreasing the liquid pressure will generally produce a smaller droplet size.

EXAIR manufactures (3) types of Atomizing Nozzles – Internal Mix, External Mix, and Siphon Fed, in both 1/4 NPT and 1/2 NPT sizes. Maximum liquid viscosity is 800 cP. Flow rates range from 0.6 GPH up to 303 GPH, so we’ll be able to find one that meets your flow requirements.

To discuss your application and how an EXAIR Atomizing Nozzle can benefit your process, feel free to contact EXAIR and myself or one of our other Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

Send me an email
Find us on the Web
Like us on Facebook
Twitter: @EXAIR_BB

The Sweet Taste of Floss Part II

Floss Stick

Floss Stick

In The Sweet Taste of Floss Part 1, I explained the benefits of using our Atomizing Nozzles to apply a liquid flavoring onto floss sticks. With that same customer, we had another opportunity to save them on compressed air and on liquid flavoring.

As described in their setup, they had a mini conveyor that would carry a 24” rod that was filled with many floss sticks. This operation was manual.  It would take the operators roughly 45 seconds to load the floss sticks.  The conveyor would move the rod through the spraying compartment in about 15 seconds.  The customer was worried about the continuous spraying and wondered if we could help in this operation.

Electronic Flow Control

Electronic Flow Control

They had a good concern because with a constant spraying, they could have an issue with fogging the work area and wasting the liquid cherry flavoring. My suggestion was to use the EXAIR model 9055 Electronic Flow Control (or EFC).  The EFC is a user-friendly controller that combines a photoelectric sensor with a timer.  It has eight different programmable on/off modes to minimize compressed air usage and in this case, liquid spray.  For this type of operation, the EFC worked great.  They did not need to manually turn on and off the system, or purchase a PLC that would require programming.  The EFC is in a compact package that is easy to mount and setup.

In evaluating their application, the Signal “OFF” Delay would be correct setting to run in this operation. (The EFC comes factory set in this mode).  The sensor will detect the part and open the solenoid immediately.  Once the part clears the sensor, then it will keep the solenoid open for the set amount of time.  For this project, they set the timer for 15 seconds.  They mounted the photoelectric sensor at the beginning of the entrance to the spraying compartment.  Once the sensor detected the rod that was filled with floss sticks, it would turn on the compressed air to the Atomizing Nozzles.  After the timing sequence hits 15 seconds, the EFC would turn off the solenoid which would stop the spraying.  It would rerun this sequence every time a rod would pass by the sensor.  This optimized their operation; especially when they had any issues with loading the rod with floss sticks.  It reduced their liquid and compressed air usage by 75%, and it kept the work area free of fog.

If you need an easy way to save on compressed air usage or in this case fluid, the EFC could be the device for you. It can save you much money in your operational costs, and during these economic times, we know that every bit counts.  If you are still a little “foggy” on the EFC, you can contact an Application Engineer at EXAIR for help.

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

 

Photo by homejobsbymom with Creative Commons license.

%d bloggers like this: