The Impact of Cold Temperatures and Lower Humidity on Static Electricity

This time of the year it is not uncommon to feel a slight shock after walking across a carpeted surface and touching a door knob. This little “jolt” is a result of fast-moving electrons leaping from your body to the door knob, or vice versa. As your feet shuffle across the surface of a rug or carpet, your body will either gain or lose electrons. Touching a conductive surface then causes these electrons to leap from one place to another. This is known as static electricity.

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If you notice, this happens to occur much more often during colder winter months (if you’re one of those fortunate people to live outside of this sensation we call “cold” please don’t rub it in!). The reason that you experience static shocks more frequently during winter is due to the relative humidity. At colder temperatures, air does not hold as much moisture as it does when it’s warm and moisture helps to conduct electrical charges. Even though you’re heating your house to a similar temperature, the air that is being drawn into your home and heated is still the dry cold air containing less moisture.

The amount of moisture in the air is expressed as relative humidity. This value is given as a percentage of water vapor in the air, compared to how much it could hold at that temperature. In conditions of lower relative humidity, static charges build up much easier. When the relative humidity is high, there’s a higher concentration of water molecules present in the air. These water molecules “coat” the surface of the material, allowing electrons to move more freely and form a layer over the material. This layer of water molecules acts like a lubricant, reducing the forces that cause static to generate. This is why static is much more noticeable during the winter months.

Gen4 Static
Gen4 Static Eliminators

There are many applications that static only appears when the seasonal climate changes. Issues can manifest in the form of nuisance shocks to operators, materials jamming, tearing or curling, product sticking to itself and to rollers, dust clinging to product, and many more. If static is causing problems in your processes, we have a wide variety of Static Eliminators available from stock. Don’t just deal with the problems until humid conditions return, get a permanent solution in place that’ll neutralize the static and eliminate a troublesome application. Contact an EXAIR Application Engineer today and we’ll help to diagnose the root cause of the problem and recommend the best solution.

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

 

Photo courtesy of Ken Bosma via Flickr Creative Commons License

Air – What Is It?

Air… We all breathe it, we live in it, we even compress it to use it as a utility.  What is it though?  Well, read through the next to learn some valuable points that aren’t easy to see with your eyes, just like air molecules.

Air – It surrounds us – (Yosuke,1)
  1. Air is mostly a gas.
    • Comprised of roughly 78% Nitrogen and 21% Oxygen.  Air also contains a lot of other gases in minute amounts.  Those gases include carbon dioxide, neon, and hydrogen.
  2. Air is more than just gas.
    • While the vast majority is gas, air also holds lots of microscopic particulate.
    • These range from pollen, soot, dust, salt, and debris.
    • All of these items that are not Nitrogen or Oxygen contribute to pollution.
  3. Not all the Carbon Dioxide in the air is bad.
    • Carbon Dioxide as mentioned above is what humans and most animals exhale when they breathe.  This gas is taken in by plants and vegetation to convert their off gas which is oxygen.
    • Think back to elementary school now.   Remember photosynthesis?
      • If you don’t remember that, maybe you remember Billy Madison, “Chlorophyll, more like Bore-a-fil.”
    • Carbon dioxide is however one of the leading causes of global warming.

      Moisture In The Air – (Grant)2
  4. Air holds water.
    • That’s right, high quality H2O gets suspended within the air molecules causing humidity.  This humidity ultimately reaches a point where the air can simply not hold anymore and it starts to rain.  The lack of humidity in the air leads to static, while lots of moisture in the air when it gets compressed causes moisture in compressed air systems.
  5. Air changes relative to altitude.
    • Air all pushes down on the Earth’s surface.  This is known as atmospheric pressure.
    • The closer you are to sea level the higher the level of pressure because the air molecules are more densely placed.
    • The higher you are from sea level the lower the density of air molecules.  This causes the pressure to be less.  This is also why people say the air is getting a little thin.

Hopefully this helps to better explain what air is and give some insight into the gas that is being compressed by an air compressor and then turned into a working utility within a production environment.  If you would like to discuss how any of these items effects the compressed air quality within a facility please reach out to any Application Engineer at EXAIR.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

1 – Air – Creative Commons – Tsurutea Yosuke – https://www.flickr.com/photos/tsurutayosuke/47732716442/in/photolist-2fHYDBG-dd5e5z-5snidD-oaU8fm-68kqiz-8sMG3P-fnqYx7-9bkTrx-5P2BDv-6R75dG-9vi5xL-5yADR-8EAFci-9NQvER-8sMGoR-4Uybwo-9bNqfB-6N9qf8-6LZyG-7MF4aZ-dehz3-5h1wXk-6uJWNq-7eQCUU-6qoUm6-8sQHxo-uqDdE-6NDHW3-8sQMDQ-7wyCsV-dd5io5-5yAwX-ZmCdh2-BMZCW-agSno-bQ8UFK-6d8Pkz-ars544-novykD-3PF1FT-W13jE9-3GSRLj-7r9Msu-6yn1Ne-32iJKf-7CPqWv-8qhcn-4Eicvh-LLgb4-54ixko

2 – DSC_0750 – Creative Commons – David Grant – https://www.flickr.com/photos/zub/24340293/in/photolist-39Kwe-2cZxjuw-6ywctR-26b7Z2F-84vqJN-bpjRN3-6aDzQR-i84BUr-xbu1Us-fxyvn-5UPDBh-VDz7nD-8Be4fP-a6MVGC-nP4end-PA5nb9-3ddwtq-nRF2yr-j4XPzo-cd5CvJ-eoGFTQ-rYNapy-pKAJpQ-pVrbq6-21hFhHB-n8hpva-7uMwPs-4EZ9ok-jGahK-foR798-JP9rcG-cMRjhu-i74Qo-2d1nE-7nXj3e-9tMib1-6JrXP-9tMdnd-4o5ZCx-6uk2LG-9Gt8K4-5xksdV-9tJgMa-9tMh8b-kkZNy5-c8oM8C-8reqky-4KXe87-aFt7kn-MNNDwU

Atomizing Spray Nozzles from EXAIR

Do you ever need to spray a liquid?  If so lets look at two of EXAIR’s Atomizing Spray Nozzles or ASN for short.  The first model we will discuss is the AD1010SS Internal Mix Deflected Flat Fan Pattern.

AD1010ss_pr_559w
AD1010SS Internal Mix Deflected Flat Fan Pattern

To begin with all EXAIR ASN’s are made from SS for durability and liquid compatibility.  As its name implies it creates a flat fan pattern that exit’s the nozzle perpendicular to the air & liquid inlets as shown above.  This unique design lends itself nicely to applications with space constraints.  The AD1010SS is the ideal choice for coating the inside of enclosures or ductwork.  It is compatible with liquids up to 300 centipoise and the air and liquid are mixed in the air cap.  The AD1010SS is designed for pressure fed applications not requiring independent air and liquid control.  What is meant by that statement is that if you vary either the air or liquid pressures you change the spray pattern and volume.  See the chart below for clarification on pressures, volumes and spray patterns.

AD1010SS Pressures
AD1010SS Chart

Next we will look at EXAIR model AT1010SS internal mix 360° hollow circular pattern ASN.

AT360circpat_pr_300
AT1010SS 360° Circular Spray Pattern Nozzle Can Be Used To Coat Inside Diameters Or Cover A Broad Area Of Over 4′

The AT1010SS internal mix 360° nozzle is designed for applications where the spray pattern must be oriented away from the nozzle in all directions.  360° nozzles are ideal where a smooth, even coating is needed on the ID of a pipe or similar ductwork.  It is compatible with liquids up to 300 centipoise and the air and liquid are mixed in the air cap.  The AT1010SS is designed for pressure fed applications not requiring independent air and liquid control.  As above if you vary either the air or liquid pressures you change the spray pattern and volume.  See the chart below for clarification on pressures, volumes and spray patterns. They also work great for operations where a mist over a broad area is needed, such as dust suppression, humidification and cooling.  See the chart below for clarification on pressures, volumes and spray patterns.

AT1010SS Chart
AT1010SS Chart

If you would like to discuss EXAIR’s Atomizing Spray Nozzles or any EXAIR compressed air product, I would enjoy hearing from you…give me a call.

Steve Harrison
Application Engineer

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Intelligent Compressed Air: Refrigerant Dryers and How They Work

We’ve seen in recent blogs that Compressed Air Dryers are an important part of a compressed air system, to remove water and moisture to prevent condensation further downstream in the system.  Moisture laden compressed air can cause issues such as increased wear of moving parts due to lubrication removal, formation of rust in piping and equipment, quality defects in painting processes, and frozen pipes in colder climates.  The three main types of dryers are – Refrigerant, Desiccant, and Membrane. For this blog, we will review the basics of the Refrigerant type of dryer.

All atmospheric air that a compressed air system takes in contains water vapor, which is naturally present in the air.  At 75°F and 75% relative humidity, 20 gallons of water will enter a typical 25 hp compressor in a 24 hour period of operation.  When the the air is compressed, the water becomes concentrated and because the air is heated due to the compression, the water remains in vapor form.  Warmer air is able to hold more water vapor, and generally an increase in temperature of 20°F results in a doubling of amount of moisture the air can hold. The problem is that further downstream in the system, the air cools, and the vapor begins to condense into water droplets. To avoid this issue, a dryer is used.

Refrigerated Dryer
Fundamental Schematic of Refrigerant-Type Dryer

Refrigerant Type dryers cool the air to remove the condensed moisture and then the air is reheated and discharged.  When the air leaves the compressor aftercooler and moisture separator (which removes the initial condensed moisture) the air is typically saturated, meaning it cannot hold anymore water vapor.  Any further cooling of the air will cause the moisture to condense and drop out.  The Refrigerant drying process is to cool the air to 35-40°F and then remove the condensed moisture.  The air is then reheated via an air to air heat exchanger (which utilizes the heat of the incoming compressed air) and then discharged.  The dewpoint of the air is 35-40°F which is sufficient for most general industrial plant air applications.  As long as the compressed air stays above the 35-40°F temperature, no further condensation will occur.

The typical advantages of Refrigerated Dryers are-

  1.  – Low initial capital cost
  2.  – Relatively low operating cost
  3.  – Low maintenance costs

If you have questions about getting the most from your compressed air system, or would like to talk about any EXAIR Intelligent Compressed Air® Product, 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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