Since air compressors require electricity to make compressed air, it is important to optimize your compressed air system. EXAIR has six simple steps, and following these steps will help you cut electrical costs, reduce overhead, and improve your bottom line. In this blog, I will cover the fifth step –intermediate storage of compressed air near the point-of-use.
I had a customer that was looking at a model 1122108, 108” (2,743mm) Super Ion Air Knife Kit. The application was removing static and debris from insulated panels which they used for large refrigerated trailers. They were worried about how much compressed air that it would use; and they were considering a blower-type system. I went through the negative aspects like noise, cost, maintenance, and ineffectiveness with turbulent air flows. But, when you are limited in the amount of compressed air, I had to look at another way. Since the process was intermittent, I used the fifth step to optimize their system to use a much better solution for their application. The cycle rate was 2 minutes on and 10 minutes off. I was able to calculate the size of a secondary tank to help their compressed air system.
I would like to expand a bit more about secondary receiver tanks. They can be strategically placed throughout the plant to improve the “ebbs and flows” of pneumatic demands. The primary receiver tanks help to protect the supply side when demands are high, and the secondary receiver tanks help pneumatic systems on the demand side. They give additional capacity at the end of distribution lines. Essentially, it is easier and more efficient for compressed air to travel out from a nearby source and into an application rather than traveling through long lengths of pipes from the distribution system.
For calculating the volume size for your secondary receiver tank, we can use Equation 1 below. It is the same for sizing a primary receiver tank, but the scalars are slightly different. The supply line for air drops will typically come from a header pipe and are generally smaller in diameter. So, we have to look at the air restriction that can feed into the tank. For example, a 1” NPT Schedule 40 Pipe at 100 PSIG can supply a maximum of 150 SCFM of air flow. This value is used for Cap below in Equation 1. C is the largest air demand for the machine or targeted area that will be using the tank. If the C value is less than the Cap value, then a secondary tank is not needed. If the Cap is below the C value, then we can calculate the tank volume that would be needed. The other value in the equation is the minimum tank pressure. In most cases, a regulator is used to set the air pressure for the machine or area. If the specification is 80 PSIG, then you would use this value as P2. P1 is the header pressure that will be coming into the secondary tank. With this collection of information, you can use Equation 1 to calculate the minimum tank volume.
Equation 1:
V = T * (C – Cap) * (Pa) / (P1-P2)
Where:
V – Volume of receiver tank (cubic meter)
T – Time interval (minutes)
C – Air demand for system (cubic meter per minute)
Cap – Supply value of inlet pipe (cubic meter per minute)
Pa – Absolute atmospheric pressure (Bar)
P1 – Header Pressure (Bar)
P2 – Regulated Pressure (Bar)
For this customer above, I am still working on this purchase. But we went from a “we don’t have enough compressed air” to a “we can possibly use the better solution with the Super Ion Air Knife”. If you find that you might be having issues with your equipment running optimally, you may be able to install a secondary receiver to your system. EXAIR offers 60 Gallon tanks, model 9500-60, to add to those specific areas. If you have any questions about using a receiver tank in your application, primary or secondary, you can contact an Application Engineer at EXAIR.
John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb
