Tag: altitude

When You Get To Asheville

Published on by Brian FarnoLeave a comment
1 – Steve Martin & Edie Brickell – “When You Get To Asheville”

Over the past week, my amazing wife and I traveled to Asheville, NC for a long weekend away. This is our second year going down, and I can most certainly say that we will be going back. Our days consisted of going to a small mom-and-pop type diner for breakfast, loading the cooler with water, and then picking a hike to hit up. This time we hiked mostly in the Pisgah National Forest and while we did not hit the same elevation as last year, we still managed to double the first hike of the week on the second day and felt great once we reached the end. I also chose to make the hikes hard on myself by carrying my trusted GO-RUCK GR1 to carry our water, first aid kit, and a 30 lb. steel plate, because you should always choose the harder thing.

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While we weren’t at elevations like Pikes Peak in Colorado, we still felt the difference in the air between being in Cincinnati and being in the mountains. Maybe it was just the fact it was cleaner. When we crested a hill on the trail and stopped to take a quick break, we looked around and realized that after all the switchbacks we had just gone through, we looked over the valley we had just climbed out of and were at the tree tops of the valley and still nowhere near the top of the mountain. This got me to thinking about how I was working harder because I had a steel plate, walking too many lunches where I just sit for 30 minutes instead of walking and that is immediately connected to the ACFM calculations for an air compressor and just how a compressor will have to work harder to produce the same volume of air when elevated because the air is thinner. This is going to change the air density, which results in a lower atmospheric pressure due to higher altitude.

Altitude is just one of the factors that matters in the calculation to determine a compressor’s output at different locations. The other factors include relative humidity, which was way better in the mountains than here in Cincinnati, and the actual temperature, again better in Asheville than Cincinnati.

If you are wondering about the equations I am referencing, we’ve blogged about them many times and even have a Webinar that touches on the math and reasoning behind these different values. Check the equation below and the links above.

In case you were wondering, the post-Ruck/Hike hydration is always better after events, it also always helps to have a good partner in crime to enjoy all the experiences with you. Thankful for the ability to connect all these hobbies and my knowledge of compressed air on top of sharing it with others. If you want to discuss how to calculate some ACFM or SCFM consumption and outputs of your compressor or application, or if you want to talk about rucking, hiking, or any of your favorite trails, give me a call, chat, or tweet.

Brian Farno, MBA – CCASS Application Engineer

BrianFarno@EXAIR.com
@EXAIR_BF

1 – Steve Martin & Edie Brickell – “When You Get To Asheville” – CBS, Retrieved from https://www.youtube.com/watch?v=4RzhTN9zW3w

Air Compressors: Air Intake and Altitude

Published on by John BallLeave a comment

Flow rate is the quantity of material that is moved per unit of time.  Generally, the quantity of material can be expressed as a mass or a volume.  For example, mass flow rates are in units of pounds per minute or kilograms per hour.  Volumetric flow rates are stated in cubic feet per minute or liters per hour.  The trick begins when volumetric flow rates are used for a compressible gas in different altitudes.

From the history of air compressors, they could calculate the volume of air being drawn into the air compressor by the size of the cylinder.  With the volume of the compression chamber and the rotations per minute of the motor, RPM, they could calculate the volumetric air flows.  As conditions change like air density, temperatures, and relative humidity; the values of the volumetric flowrate changes.

Since we are looking at the intake flow rates of an air compressor, what happens when they run at different altitudes?  I remember that when I was in Denver, I got easily winded.  Now, this could be that I was out of shape, but it was also because the air is less dense.  That means for a volume of air, the mass of air was less.  This is called the specific volume.  Air compressors work the same way.  So, let’s look at the Ideal Gas Law; Equation 1.

Equation 1:

P * v = R * T

v – Specific Volume

R – Universal Gas Constant

T – Absolute Temperature

P – Absolute Pressure

In a comparative relationship, we can show the changes that can occur with an air compressor at different altitudes.  Since we are looking at altitude, the air density and pressure will change at different elevations above sea level.  If we keep the temperature the same, we can derive a formula from Equation 1.

Equation 2:

P1 * v1 = P2 * v2

P1 – Absolute Pressure at Sea Level

P2 – Absolute Pressure at elevation

v1 – Specific Volume of air at P1

v2 – Specific Volume of air at P2

Specific volume is the inverse of density, so it has the units of ft3/lb or M3/Kg.  If we use an example of a 40 CFM air compressor at sea level, it will produce 40 cubic feet per minute.  We can calculate the flow rate of air that it can produce at 5,000 feet of elevation.  The absolute air pressure at sea level is 14.7 PSIA, and at 5,000 feet, the air pressure is at 12.2 PSIA.  So, if we look at Equation 2, we can rearrange the values to find the change in specific volume from sea level (position 1) to 5,000 feet (position 2):

v2 / v1 = P2 / P1 = 12.2 PSIA / 14.7 PSIA = 0.83

With the 40 CFM air compressor, it will now only produce 40 * 0.83 = 33.2 CFM of compressed air at 5,000 feet.

When sizing an air compressor, it is important to know the conditions.  In this blog, I discussed the effects of altitude as it applies to the intake of an air compressor.  But, no matter the size, elevation, or type of air compressor, EXAIR blow-off products like Super Air Knives, Super Air Nozzles, and Safety Air Guns will help you to save energy and increase safety.  You can speak to an Application Engineer to see how.

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

Air – What Is It?

Published on by Brian FarnoLeave a comment

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