Internal Mix Atomizing Spray Nozzle Used In Feed Additive Process

Last week I took a call from an agricultural customer looking to replace the spray nozzle used in their feed additive process. The soy oil/beeswax solution they are applying to the feed, is slightly viscous (close to 100 cP) which seems to be clogging the tight clearances inside the current nozzle, resulting in varying flow rates and an erratic spray pattern. They had tried to contact the current manufacturer several times for a solution but were unhappy with the lack of assistance they were receiving, not to mention the long lead times of 6-8 weeks for a replacement.

After further discussion, they confirmed they weren’t as concerned with the flow rate or spray pattern, as they were with the nozzle potentially getting clogged.  They were able to obtain some internal dimensions of the existing nozzle and after further review, I recommended they use our Model # AF1030SS Internal Mix Flat Pattern Atomizing Nozzle as a replacement. This nozzle has larger inside diameters which would reduce the potential for clogging. Our Internal Mix Atomizing Nozzles mix the liquid and air inside the air cap and produce the finest atomization. The flow rate can be changed by adjusting the control valve on the nozzle and/or by adjusting the liquid pressure. Internal Mix nozzles are capable of handling fluids up to 300 Centipoise. All of our Atomizing Nozzles are In STOCK, so delivery is never an issue.

Model AF1030SS Internal Mix Flat Fan Pattern Atomizing Nozzle

When considering an Atomizing Nozzle for an application, there are some general parameters that can be helpful in making the best selection.

  1. Do you have a pressurized liquid source?
  2. What is the fluid viscosity?
  3. What spray pattern best fits the process?
  4. How much flow (GPH/LPH) do I need?

If you have an application requiring a fine mist of atomized liquid spray, please contact an application engineer for assistance.

Justin Nicholl
Application Engineer
justinnicholl@exair.com
@EXAIR_JN

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

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Atomizing Nozzles: Common Questions About Viscosity

As EXAIR Atomizing Nozzles become more popular with our customers, we are getting a lot of interesting questions that folks have regarding the nozzles themselves and the information that we provide so the customer can make an informed decision.

One set of questions has to do with the flow rate information presented in our technical data for the Atomizing Nozzles. The question is, “What is the fluid that is being used to derive your flow data given in the charts?”  That answer would be plain old water (H2O).  The next question that comes is, “What if my fluid has a higher viscosity? How do I figure out the flow rate that will apply to that?”

The answer is that you will not know until you actually perform a test with your specific material. However, if you apply some simple logic to the question, a higher viscosity fluid is going to flow less than water through an Atomizing Nozzle. So, to compensate, you can select an Atomizing Nozzle size which has a higher water flow rate in order to compensate for a thicker fluid. A chart for viscosity of common fluids can be accessed here.

You do have options in terms of which style of Atomizing Nozzle you choose for the application. For example, fluids that have viscosity up to 200 centipoise can work well with either a siphon type or an internal mix type Atomizing Nozzle (an internal mix type can work with viscosity up to 300 centipoise). The siphon nozzle option is for applications where the fluid is not pressurized but is available from a nearby container (this can also be set up to be gravity fed type depending on the height of the fluid in relation to the nozzle). The internal mix nozzle is used when the applied liquid can be pressurized by a pump or perhaps by a pressure pot.

For applications where the fluid is over 300 centipoise, an external mix Atomizing Nozzle is the suggested product to use. Because the air and the pressurized fluid mix out in front of the nozzle, the liquid is not subject to the back pressure present upon it in an internal mix nozzle configuration. Therefore, the liquid pressure and air pressure are completely independent. This means a much higher pressure can be used on the high viscosity fluid to push it through the nozzle and be atomized.

The variety of nozzles available with different configurations, flow rates, spray patterns and abilities can be a little difficult to navigate without some help. That is expressly why we are here.  To help customers determine what they need in this range of product.

If you have been considering an Atomizing Nozzle for an application, please let us know if you have any questions or just want to talk things over to make sure you are headed in the right direction. We are here to help make the decision an easy one.

Neal Raker, Application Engineer
nealraker@exair.com