You Have To Start Somewhere.

The school year is in full swing here in Cincinnati and all three of my daughters have different extracurricular activities they partake in. This fall, that equates to divide and conquer for my wife and me 4 nights of the week for practices then the weekends are also separate and conquer, but mainly on Saturday. This eats away at times we would typically use at home to get some walking in or even just generally getting stuff done. This schedule combined with working earlier has caused me to lose almost all workout desire. That is until I got to the first practice my oldest had which just happens to be held on my alma mater’s campus and is right next to Nippert Stadium.

When we arrived I noticed most parents were just hunkered down in their cars and watching movies or doom scrolling social media. I try to avoid doing that for 90 minutes straight if I can and so far I have. I started hitting the stairs at the University of Cincinnati’s Nippert Stadium with my 35-pound ruck on my back. While my goal is to be able to complete the standard they have for their 9/11 memorial event I also want to get back into the shape I was in when I did back-to-back GORUCK events and could crank out burpees without crying on the outside. After going up one column of stairs from the field to the concourse level I go across and down the next set until I have done every column of stairs that go from the concourse to the area directly. For their event, I have to complete two laps which will equate to the number of steps within one of the towers.

So to train, I started with seeing how many sets I could do without feeling like I was going to not be able to reach the top and walk to the car. Surprisingly, I was able to get about half of the stadium done. Then I still had another hour to kill, so I hydrated a bit and rucked on over to the track/soccer field where I could walk the track and watch co-ed intramural flag football games while I did laps. Finally, I threw in some ruck PT exercises as a cool down and ended back at the building her practice was in. When I got to work the next day I felt like I got beat with a sack of oranges from my waist down. Then, on Thursday the thought crossed my mind as I hadn’t slept much the night before to just relax, then I had a buddy ask if he could come do stairs with me, and so we did it again Thursday night.

So from now until the end of the school year, I will more than likely be rucking on or around UC’s campus and Nippert Stadium to ensure I get back into a reasonable condition without having to lose more time with my family. This isn’t always easy and doesn’t come without pain. That pain though comes with added energy and increases in my mental position as well, so I am open to more things.

The same thing can be said about an industrial compressed air system. If you just trudge through every day and don’t look at any part of your facility, it is going to cause some pain when you first start to look at it. The first step is to acknowledge that something needs to change, and you have to have that finished goal of more capacity and capability available. The best place to start on your compressed air system is at the start with mapping out the system and getting a base measurement of where you are at for consumption.. This is the first step in our 6 steps of compressed air optimization, and we can help with every step along the way, You just have to reach out to us, your accountability partner for efficient compressed air.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

Air Compressors: Air Intake and Altitude

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