Ways to Measure Air Compressor Performance and Know if You Need an Audit
June 19, 2024
Five Key Applications of Rotary Screw Vacuum Pumps in the Food and Beverage Industry
July 3, 2024Five Critical Differences Between a Single-Stage and a Two-Stage Air Compressor
Kaishan USA | June 26, 2024 | Uncategorized
Reliable, energy-efficient air is needed for applications like medical device manufacturing.
Single- and two-stage air compressors have been around for a long time. However, other than the fact that a two-stage air compressor costs more, many end-users are not fully aware of the differences. Especially the ones that determine whether a two-stage model is a worthwhile investment.
Not surprisingly, a single-stage compressor uses one compression chamber to compress air to the desired pressure, while a two-stage air compressor uses two. The two look very similar.
So why would anyone pay more for the two-stage unit? We outline five critical reasons why below.
1. A Two-Stage Compressor Is More Energy Efficient
A two-stage air compressor like the KRSP2 premium rotary screw air compressor splits the workload into two separate stages. Here’s how that works.
But first, a contrast.
A single-stage compressor like Kaishan’s KRSP premium rotary screw air compressor generates a compression ratio of 7.8 to 1 to create 100 PSIG of pressure. It is one of the most cost-effective compressors on the market, and Kaishan backs it with an industry-leading lifetime airend warranty.
But, as mentioned, the KRSP2 divides that work into a first stage of 2.8 to 1, followed by a second stage of 2.8 to 1. Plus, before the second stage, the air passes through an interstage cooling step, removing some of the heat of compression and building efficiency.
By building on the pressure generated in the first stage, the KRSP2 generates more compressed air for less energy. The bottom line? A two-stage air compressor generates up to 15 to 20% more flow than a single-stage compressor of the same size (HP). Paybacks on energy costs alone may be less than two to three years.
Kaishan’s KRSP2 two-stage rotary screw air compressor is one of the most energy-efficient machines on the market.
Variable-Speed Drive
Equipping your KRSP2 with a variable-speed drive can add even more efficiency at part loads. Our VSD version of the KRSP2 is one of the only two-stage units that are available in sizes as low as 30 HP.
For more on the advantages of variable speed drives, see our blog post, “How Variable Speed Drive Rotary Screw Air Compressors Save You Money.”
2. It’s More Reliable and Long-Lasting
Using two stages results in less mechanical stress and generates less heat, reducing wear and tear and extending the life of components. Similarly, because the KRSP2 spreads the work over two stages with four discharge bearings on the first stage and three on the second stage, those bearings have less stress than the two bearings that carry the entire thrust load in a single-stage unit.
Lower forces and more bearings result in longer life. The KRSP2 is built to last, enabling us to offer an industry-leading lifetime airend warranty.
An industry-leading lifetime airend warranty backs Kaishan’s KRSP and KRSP2 screw compressors.
3. You May Not Need as Large a Compressor
Because a two-stage compressor generates 15 to 20% more compressed air flow than a comparable single-stage unit, you may be able to use a smaller model. You may, for example, be able to replace a 300-HP single-stage compressor with a 250-HP two-stage KRSP2. That could allow you to cut the initial cost gap to 15 to 20%.
It’s all about matching the compressor horsepower-to-CFM ratio that fits your needs.
4. You’ll Enjoy Lower Operating Cost
The reduction in electricity costs, lower lifetime maintenance requirements and fewer part replacements makes operating costs for a two-stage compressor lower than for a single-stage unit.
You can save even more money by using the KRSP2’s increased air flow to select a compressor with a lower horsepower rating. Need help determining how much flow you need? See our blog post, “How Many CFM Do I Need? Air Pressure by Different Applications.”
5. You Have a Lower Total Cost of Ownership
Yes, a two-stage unit requires a larger expenditure. But with the reduction in energy costs and downtime, the opportunity to select a smaller compressor and the lowered maintenance and operating costs, a two-stage compressor delivers long-term benefits.
And remember, acquisition costs amount to only 12% of the total cost of ownership, according to the U.S. Department of Energy. You pay the initial cost one time. You’ll be paying the power and maintenance costs for the life of the compressor.
The U.S. Department of Energy estimates that the cost of purchasing an industrial air compressor is only 12% of the lifetime cost of owning and operating a compressed air system.
When to Use a Two-Stage Rotary Screw Air Compressor
Because of the initial cost, we find that two-stage air compressors are most attractive in the following situations:
-
- As a base-load compressor in a two- or three-compressor configuration, running at 100% full-load capacity. For more on increasing reliability and energy efficiency with a three-compressor system, view our blog post, “Everything You Need to Know About Sizing Industrial Air Compressors for Manufacturing.”
In a three-compressor system, starting from left, a trim compressor handles the load on weekends, holidays or a limited third shift. Then, in the center, when you’re operating at normal levels, a base unit such as the KRSP2 comes on and immediately goes to full capacity. The trim unit, usually a VSD air compressor, then kicks in as needed to handle fluctuations in demand. An additional backup unit is in place should one of the other units fail.
-
- Mass production applications where reliability is critical, such as general manufacturing, automotive, aerospace, food and beverage and glass manufacturing.
- Companies looking for an environmentally friendly unit with high energy efficiency and long lifespan.
Because of their reliability and efficiency, two-stage rotary screw compressors like the Kaishan KRSP2 premium rotary screw air compressor are an excellent choice for base load compressors.
In fact, by manufacturing two-stage air compressors as small as 30 HP, Kaishan is making these units cost-effective for a much larger universe of industrial users.
Local Help
If you’re considering moving to a two-stage rotary screw compressor, it’s probably a good idea to work with your local compressed air professional to evaluate your compressed air system and determine the potential benefits. Kaishan USA works with a nationwide network of independent distributors, who can provide on-site help and consultation as needed.
Key Takeaways
-
- A two-stage air compressor will generate up to 15 to 20% more flow in the same size air compressor.
- Since a two-stage air compressor generates more air flow than a comparable single-stage unit, you may be able to use a smaller model.
- Savings on energy costs for a two-stage air compressor may result in a payback of less than a year.
- Operating costs, including electricity costs, maintenance and replacement parts, will be lower for a two-stage model than for a single-stage air compressor.
- Total cost of ownership for a two-stage air compressor is significantly lower.
Let Us Help
Deciding whether you can benefit from a two-stage rotary screw air compressor is an essential step for your compressed air system and all the processes that rely on that system. If you need help deciding if a two-stage compressor would be right for your operation, get in touch with the experts at Kaishan. Contact us today.