By: Wayne Perry
When putting together a compressed air system, temptation is all around you. You want the best system, but having the best doesn’t mean grabbing whatever looks good. Build a system that meets your needs not your wants. Focusing on your system’s needs and avoiding these seven deadly sins will keep you from needing to confess when your utility bill arrives.
- Lust— Don’t lust after a variable frequency drive compressor. Many utilities offer rebates for a VFD, but they are not always the best solution. Sellers often make blanket claims of huge savings, but if your compressor will run fully loaded more than 75% of the time, savings are very limited. Keep in mind that they are more expensive and have drive losses which need to be considered. If you have an application where the load varies between 40-80% of compressor capacity, then a VFD makes sense. Do the math before you buy one to make sure your system will benefit from using this technology.
- Gluttony— Don’t be a glutton with your air treatment. Dry air sounds great, but there is such a thing as overkill. And overkill is expensive. This is especially true for larger, industrial compressed air systems supplying multiple processes. Take a hard look at your system and determine what level of filtration and dew point each segment needs. If you need a desiccant dryer for only part of your process, then size it for that part only. You’ll not only save by buying smaller capacity equipment, but also on pressure drop, air loss, and energy.
- Greed— don’t be greedy for air by oversizing your system. Bigger is not always better. Oversizing means you are paying for more energy than you need to. In some cases, if the compressor is too large for the demand, it may not come up to temperature, causing excess condensate. The machine will cycle on and off, which puts unnecessary wear and tear on the motor, valves, and seals. Figure out the amount of air you need for your system and select a compressor that will meet it. And, if you determine your load varies widely, consider using a VFD.
- Sloth— Don’t be lazy attending to leaks. Leaks occur and reoccur and need to be continually monitored and repaired. The US Department of Energy estimates that as much as half of all compressed air is wasted, with an average of 25% lost to leaks. I’ve seen annual leak losses range from $3,000 for smaller systems and up to $600,000 for larger ones. Check for leaks and repair them once you find them. You’ll be putting money back on your bottom line every time you do.
- Wrath— Beware the wrath of poorly controlled compressors. If you notice pressure spikes, disruptions in your air supply, or compressors cycling on and off, that means the compressors need to be controlled with a master system controller. A master controller monitors system demand and selects the right combination of units to meet it in the most efficient way possible. Don’t leave them to their own devices. Keep them under control.
- Envy— Don’t be envious of other plants with the newest technology simply because it is new. Choose what is best for your application. Some installations are using the latest in remote monitoring and taking advantage of cloud-based solutions. Good for them. Don’t let the latest and greatest distract you from your system’s needs. Stay focused on what is right for your installation.
- Pride— Don’t be so proud of your system that you fail to monitor its changing needs. You’ve worked hard to put together an efficient system and in the process you’ve saved a lot of money in energy costs. Don’t rest on your laurels. A good way to stay on top of your system is by doing an annual compressed air audit. This will help you see trends and react to any changes that might be happening in your demand profile.