Common Compressed Air Pressure Supply Problems

Our applications engineers often field calls with woes of compressed air products not functioning to their fullest capacity. Many companies struggle with compressed air issues, and we're here to help you through it. 

Common Compressed Air Pressure Problems

At the heart of it all is ensuring that you maintain the right pressure to guarantee your compressed air tools are working effectively. It's possible you're spending money to operate your air compressor at a pressure that is higher than necessary, just to generate the pressure needed at the tool's point of use. If so, it's likely there's a problem with the supply side of the system.

In many cases, the problem is inadequate compressed air pressure available to operate the product. When this happens, we're often able to recommend a solution that not only solves the supply side pressure issue but also ends up saving money and improves the overall efficiency of the compressed air system. These are first places to check when you have inadequate operating pressure* for the compressed air tools:

  1. Accessory Components – Often, the compressed air filters, valves (manual or electrically actuated), or pressure regulators in the supply line are improperly sized, causing restriction to airflow. Sometimes changing the component size to the next larger size will solve this problem. The best way to determine the proper compressed air component size is to first determine the flow factor (Cv) required for that component. The flow factor can be determined using a simple formula: 

    Flow factor (Cv) = required compressed airflow (in scfm) / divided by 25

    Note: This formula works only for 100 - 110 psig compressed air and where a 5 psig pressure drop across the component is acceptable. For example: if you want to select a solenoid valve to control airflow to a 35 scfm vortex tube, Vortec model 308-35-H. The vortex tube will operate at 100 psig and consume 35 scfm of air. The Cv of the solenoid valve should then be 35/25 = 1.4 Cv or larger.

  2. Air Compressor – Your compressor must be large enough to handle the peak demand of all connected air tools in use. If there is a significant variance between the peak demand and the average demand, a storage tank can be beneficial. A qualified professional will be the best person to help determine the necessary air compressor and accompanying storage tank size. Everyone's specific compressed air demands vary widely, however, a good rule of thumb is that for every one horsepower, 4 to 5 scfm (113 to 142 slpm) of air at 100 psig (6.9 bar) will be produced by the air compressor, depending on its efficiency.

  3. System Piping – This can be a problem for plants that have grown and haven't changed their piping layout to meet their evolving needs. Piping should be sized, and the routing designed so that there is minimal pressure drop across the entire system (from the point of air generation to each point of use). Your system should be designed thinking about future facility needs. Piping has come a long way in recent years. Gone are the days of black iron or galvanized pipe. Now smooth bore aluminum piping is available from multiple manufacturers and requires no threading. It's connected with simple, compression-type fittings that make installation a simple procedure. A pipe sizing chart is included with the instructions for all Vortec products to help determine the appropriate pipe size based on the volume of air flowing through the pipe.                                               
  4. Compressed air filters -  Filters with 5 micron (.0002" particle size) elements are recommended for most Vortec products ." General purpose" compressed air filters typically have filter elements for removing particles that are 40 microns (.0016") or larger in size. A 40-micron filter that is rated for 25 scfm (708 slpm) of airflow will not flow 25 scfm of air if the filter element is changed to a 5-micron element. Typically, a 40-micron filter will lose anywhere from 8 to 27% of its flow rating when the element is changed to a 5-micron element.

    As the tiny pores in a filter element become loaded up with dirt, it restricts input airflow resulting in lower pressure at the outlet and, therefore, lower pressure at the air tool. Filter elements should be changed regularly. However, when the pressure downstream becomes a performance issue with the air tool, it's a necessity. We recommend changing the filter element when the pressure drops across the filter is 10 psig (.7 bar) or greater.

Case Study: Vortec had the opportunity to work with a major manufacturer of large industrial globe, gate, plug, and butterfly valves used in various chemical industries. They were having trouble cooling these valves from temperatures exceeding 700°F down to 90°F, or less, in under 15 minutes (it was taking closer to 45 minutes). Vortec was able to do a visit and recommend a few system changes that allowed them to quadruple productivity. Click here to look at the changes that helped them decrease their cooling time from 45 minutes to 12 minutes.

* Do not confuse operating pressure with other pressure terms. "Operating pressure" is the dynamic pressure that that is present at the inlet of the air tool when it is operating at the desired pressure. This is NOT the same as static pressure. Static pressure is the pressure at the inlet of the air tool when it is NOT running. The static pressure will always be greater than the operating pressure. If there is a very large difference between the static pressure and the operating pressure, then one (or more) of the reasons covered above is the culprit.

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