Ways an air compressor can maximize manufacturing and minimize energy use
Even the most experienced compressed air users may be surprised by some of the most significant ways to boost manufacturing productivity and cut energy consumption.
Learning Objectives
- Understand the significance of header pressure in improving flow and reducing energy consumption.
- Learn the importance of properly sizing a compressor and the downsides of oversizing.
- See how a three-compressor configuration can virtually eliminate downtime and increase productivity.
Air compressor insights
- Increasing system pressure decreases flow.
- Too much is often as bad as not enough in sizing a rotary screw air compressor.
- Turning a compressor off may be the most crucial step in improving energy efficiency.
Compressed air offers some obvious ways to maximize manufacturing productivity while reducing energy use, such as finding and fixing leaks or adopting good maintenance practices.
However, several less-than-obvious ways exist to increase manufacturing capability and cut energy consumption. Some are so off the beaten path or surprising they might seem counterintuitive.
Mastering these techniques will help you increase production, provide more consistent, high-quality air and save energy – and money (see Figure 1).

Figure 1: This compressor installation by Texas Compression Services shows a backup compressor and ample storage, both critical factors in improving manufacturing uptime and reducing energy costs. Courtesy: Kaishan USA
Counterintuitive ways to save energy with compressed air
You may have already made cost-cutting and energy-saving efforts in your plant, but there might be seemingly obvious ways to boost manufacturing capabilities while seeing real savings. Here are four tips.
1. Reduce pressure
Suppose your compressor is producing air at 115 pounds per square inch gauge (psig). But workers at some of your end-use applications in a remote part of your plant say they need more pressure.
You do what too many managers do and boost the pressure coming out of your unit to 120 psig. And what happens? It doesn’t work. In fact, the users at the remote locations report they are getting even less air.
Can that be right?
It can be. And there’s a good reason. It all goes back to air compressor basics and the inverse relationship between pressure and flow, measured in cubic feet per minute (cfm).
Your 40-horsepower (hp) compressor may be rated to deliver pressures up to 150 psig. And it may be able to generate up to 175 cfm of flow. But it can’t do both at the same time. Increasing the pressure results in less flow. That’s the tradeoff between pressure and flow – if psig goes up, cfm goes down. And vice versa.
When you increase the pressure to remote use, the flow decreases. Plus, you’re putting extra mechanical load on your equipment and making your airflow inconsistent.
Then there are leaks. Every system has at least a few leaks and plugging them is a never-ending struggle. When you increase your pressure from 115 to 120 psig, those leaks are under greater pressure. The leaks get bigger, more air is wasted and the flow goes even lower.
The same thing is true of valves or regulators used to avoid over-pressurizing specific end-use equipment. If you’re setting the pressure to service your high-psig uses, you must install regulators on the rest of your system to avoid over-pressurizing – and possibly damaging – end-use equipment. As with leaks, if those devices get another 5 psig of pressure to siphon off, you’ll lose even more flow.
That’s how some facilities find themselves running header pressures of 115 psig or even 125 psig when they only need 100 psig or less.
That’s a lot of wasted energy. And it most likely results in inconsistent airflow at the end-use tools (see Figure 2).

Figure 2: Most operators run their compressed air system (orange line at top) much higher than system demand (green line). Most systems can be held to +/- 2 pounds per square inch gauge (psig) with proper storage and control. In this case, system pressure appears to be about 25 psig more than demand. Courtesy: Kaishan USA
2. Set your header pressure as low as possible
The goal is to keep your header pressure as low as possible.
- First, identify your high-use applications. If they require significantly more pressure than your other uses, you may consider installing a dedicated compressor or booster to meet their needs.
- Then, slowly scale back the pressure for your other uses until you find the lowest-possible pressure that can meet the needs of your end-use applications.
Reducing the pressure on a fixed-speed compressor will cut power consumption and increase cfm delivery.
Many facilities find they can lower their header pressures from the 120 to 85 psig or even less, saving significant energy.
Compressed air is, after all, a facility’s fourth utility, joining water, electricity and gas in meeting basic needs. As a result, compressors typically have the largest motors in most industrial plants and are frequently the largest energy consumers.
The rule of thumb is that every 2 psig increase of pressure results in a 1% increase in energy consumption. So, a 120- to 80-psig reduction could save 20% in energy consumption and, by extension, costs. A reduction also can produce more even, reliable airflow.
Not surprisingly, cutting your header pressure isn’t the only time when too much is as bad as not enough.
3. Don’t oversize
Most production people and facilities managers want to ensure their air compressor has enough power. They might rationalize it as room to grow.
But unless a space or equipment expansion is imminent or even under construction, you’re asking for trouble if you oversize an air compressor.
Rotary screw air compressors — the compressors of choice these days in most industrial applications — are designed for a 100% duty cycle. If they run at less than that, you’ll waste energy and run the risk of rapid cycling.
When a compressor rapidly cycles by constantly turning off and on, it will require more maintenance and downtime because of the increased wear and tear on the motor, valves, bearings and other parts. All that starting and stopping increases thrust loads, shortening bearing life. There will also be more carryover of moisture and oil, higher energy use and electrical costs and your compressor could overheat.
Worst of all, a rapid-cycling compressor will have a shorter lifespan. It’s not out of the ordinary for a compressor to need major repair or replacement after only six months of excessive rapid cycling.
As a result, you’ll want to make sure your compressor is sized correctly for your application and that it has adequate storage. Even if you plan to expand in a year or so it’s better to size a new compressor for your current needs and add another when extra capacity is needed.
If your company suddenly changes plans or even delays its expansion, you could be headed for more service and higher electricity costs. Companies that overbought have been able to pay for a new compressor with energy savings alone. Some have even lost warranty protection because the unit was not appropriately sized for their application.
You can even oversize when replacing one 150 hp compressor with another because today’s models are more energy-efficient than old equipment.
For all the same reasons, less is also more when your compressors are running.
4. Turn a compressor off
Many facilities have more than one compressor, and most of them operate at the same time. Companies add compressors as they increase production capacity or add new end-use equipment or tools. Or perhaps they want some redundancy for emergencies or future expansion.
Equipment manufacturers don’t help. They often add buffers to their cfm requirements to ensure their tools get enough juice.
In most cases, facility managers with multiple units set them all at the same pressure to share the load. If you have several rotary screw compressors running at 30% load, they’re probably consuming 60% to 80% of the electricity they’d consume at full load. It’s much better to turn off some of your compressors.
Here’s how that might work:
- Set a first compressor to your target pressure of 120 psig.
- Set your other compressors to turn on at successively lower pressures to supplement that base-load unit as needed.
- The second unit in this scenario might come on if the pressure drops below 116 psig, the third at 112 psig and so on (see Figure 3).

Figure 3: This graph of a system’s efficiency shows the impact of a master controller as it turned on (left side), turned off (center) then turned back on again. Courtesy: Kaishan USA
Adopting a three-compressor configuration
The ideal is to have all your units arranged in a three-compressor configuration. In a three-compressor configuration, your compressors are organized as follows:
- A base load compressor is sized to meet your system’s minimum compressed air load. Its output does not change as demand varies. It runs full bore, or it is turned off. Depending on your demand profile, you may choose to have more than one base load unit.
- A trim unit kicks on when the demand rises above the minimum load. Designed and sized to meet changing demand, your trim compressor should be the unit best at running at partial loads. That usually means trim units are rotary screw air compressors equipped with variable-speed drives.
- A backup should be in place to provide airflow when a base or trim unit goes offline. It should be sized the same as the base load equipment to effectively meet all system needs.
The goal of a three-compressor configuration is to eliminate the possibility of unplanned downtime (see Figure 4).

Figure 4: Using a three-compressor configuration virtually eliminates downtime, reduces energy consumption, reduces maintenance and cuts electricity costs. Courtesy: Kaishan USA
Many facility managers may be reluctant to commit to the extra expense of a backup unit, preferring instead to have a single machine to maintain and service. But one compressor-related instance of downtime could easily match or even dwarf the added cost.
A three-compressor approach will provide other benefits.
- You’ll reduce maintenance costs because the units won’t need service as frequently, and you can probably handle most of the work during planned shutdowns.
- You’ll meet demand with smaller compressors optimized to be as energy efficient as possible and reduce your carbon footprint and electricity costs, typically 80% of your compressor’s lifetime costs.
- With a reliable rotary screw air compressor in place as a backup, you’ll avoid emergency service costs. Most plants without backup units are forced to rent portable diesel-powered compressors, which need refueling every 12 hours and new oil and filters every 250 hours, costing you more.
Achieving energy and cost savings with the help of an expert
Taking full advantage of counterintuitive measures like reducing pressure, appropriate sizing and three-compressor configurations probably requires the help of a local expert.
Unfortunately, many companies don’t have the in-house expertise to meet the demands of more sophisticated equipment like compressed air systems (see Figure 5).

Figure 5: This audit by a compressed air professional documents a compressor’s air pressure and power consumption over a week. Courtesy: Kaishan USA
However, they can achieve significant savings by relying on a trusted consultant to help them with system design and optimization, maintenance services and supplies, thereby maximizing their manufacturing capabilities and minimizing energy consumption.
Shawn Wood is a project manager at Kaishan USA.
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