In March 2024, Hitachi Global Air Power announced the launch of Sullair TS Series lubricated rotary screw air compressors, debuting an innovative two-stage airend with an over/under design, patent-pending interstage cooling, and a lighter, more compact form. The TS Series includes nine models ranging from 984 to 2033 cfm, 100 to 200 psi (7 to 13.8 bar), and 250 to 350-horsespower (190 to 260 kW).
To mark the occasion and explore what makes the TS Series the most efficient Sullair lineup ever, Roderick Smith, publisher of Compressed Air Best Practices® Magazine, sat down with Hitachi Global Air Power President and CEO John Randall for a one-on-one interview. Topics include air compressor advances, the need for water-efficient solutions and meeting needs for a variety of customers and industries.
Smith: What are the main points of interest about TS Series for customers? What are the advancements in the two-stage technology?
Randall: Two-and-a-half years ago we started looking at chartering a product to replace our legacy TS-32, which is the tandem air compressor we have today. We wanted to make sure the new product we designed did a couple different things.
One, it had to be best-in-class efficiency in every region. We wanted to ensure we were doing things that were going to reduce energy consumption for our customers. We are focused on our customers' primary vision of conserving energy, eliminating carbon where we can, ensuring we're doing the right things. Not only for ourselves, but back through our supply chain, to help us reach the Hitachi goal of carbon neutrality in all our facilities by 2030 and throughout our value chain by 2050.
Another piece is the serviceability aspect and then the connectivity with our AirLinx® platform. Helping customers understand how the air compressor's performing, what it looks like, helping them lead to standard and scheduled maintenance to keep high levels of efficiency in place.
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John Randall, Hitachi Global Air Power President and CEO.
Smith: John, that's exciting. And when you say best-in-class efficiency, what class are you talking about? What's the product category?
Randall: 190 to 260 kW, air-cooled or water-cooled, lubricated, two-stage rotary screw air compressors for specific power. We are best-in-class for efficiency when you look at fixed speed for most nodes – particularly at the larger kW nodes. There are one or two nodes that were just a few cfm off versus some of the competition at the lower kW end, but our efficiency was still best-in-class.
The journey for this began in 2017. All the learning from the LS Series single-stage, lubricated, rotary screw air compressor launch – the easy-off panels, the touchscreen controller, the easy serviceability – all of those things, that's part of the DNA of this product. We didn't forget what we learned on the LS; we just took it to the next level.
To create some excitement around its latest innovation, Hitachi literally rolled out the red carpet for the debut event. Employees were treated to a “Taco Twos-day” lunch.
Smith: I read that you have something like 30 unique parts between the LS and the TS Series using this whole LS Series design platform.
Randall: We tried to minimize the number of unique parts between the single-stage and the two-stage. When we go back to serviceability, that makes it easier for our distributors to have the right parts in stock, whether they're servicing somebody with a single-stage, two-stage or combination of the two.
Smith: Hitachi Global Air Power is becoming a pretty unique company in our industry as a major air compressor airend designer. Can you talk about the depth of the investment there? What did you do in the R&D process to come out with a new two-stage airend that’s groundbreaking?
Randall: This was a clean-sheet development for our engineering team, but we incorporated a lot of things from our original Sullair LS-90 and 110 launch many years ago.
Looking at the airend, we understand some of the challenges of space. This is a completely different configuration and build of an over/under first-stage, second-stage airend versus the long tandem airends that we build today.
We know weight is a big issue for some of our customers, and putting these larger air compressors up on second-story platforms, we wanted to be mindful of the space but not compromise performance, durability and reliability.
In designing that over/under, we looked at the modularity concept. How do we look at the castings, the stator housings, what could be common within that platform, whether it's a single-stage or a two-stage product? And then how could we potentially even expand into higher kilowatt ranges using some of those same components within a new or larger kilowatt air compressor?
We eliminated about 40 leak paths by bringing all of the oil galleries internal to casting, eliminating all the piping and valving on the exterior. We eliminated roughly 40% of the fasteners. And then went to standard fasteners, making it easier for maintenance if there needs to be any kind of change in the future.
Smith: The over/under design, what has that done besides reduce space? What is it about that design versus the tandem that caused improvements?
Randall: A part of that is we have some patent-pending interstage cooling between the first and second stage, which aids us with efficiency. The space claim is big. The way we set up flow between the stages gives us a more efficient way to compress the air.
We looked at the gearing from the old to the new. There are some things we did in there differently, which allowed us to maintain durability without compromising improved performance.
Our proprietary electronic spiral valve is managed by a fractional horsepower electric motor, so there's no air loss. Our old two-stage used a pneumatic control, which was a detriment to some of the flow. It also didn't have quite the pressure control that we liked. The new is up to +/-1 psi, so we had the ability to develop the system to have much better control for the customer in managing their process where that pressure finite needs to be held very tightly.
Smith: What benefit do customers get when you can go to them and offer them the three models for every flow range? The base model, the spiral valve and the VSD options?
Randall: A lot of it is based on the customer's need. We try to dissuade customers from buying an air compressor that's too large for what they need because everybody knows, "Oh, I'm going to grow and I'm going to need a bigger compressor one day. Let me just get it now."
Where we do have customers that are trying to grow, if we know they have something a little bit bigger, we want to make sure we can efficiently unload it and meet that lower demand versus the peak demand.
That’s where a spiral valve comes in. The upper range of an unloaded air compressor with a spiral valve is more efficient than a variable speed drive, but the spiral valve can't turn all the way down like a variable speed drive can. Now, you don't want to be all the way down in that cycle because then you have a much larger compressor than what you need.
Smith: Can you talk about the customer benefit of having spiral valve and VSD options for part-load conditions? Is there a fixed turn-down range for spiral valve and the VSD?
Randall: Our spiral valve will turn down 50% and a lot of VSDs will go down to 80%.
A cement plant – you know how that powdery stuff can get everywhere – they'll use that pressure differential and then also the flow differential to be more efficient in loading and moving powder with the cement. But the drives just will not last. If you've got to replace a large piece of equipment like that, it can cost tens of thousands of dollars. At some frequency, that is a maintenance repair no customer wants.
A spiral valve, being simple, being mechanical, being all within the airend itself, there's zero maintenance to it. It’s a great way to improve efficiency when you don’t need that peak demand for air.
Smith: I just got back from Spain where we're starting preparations for our first European conference in June 2025. The only thing engineering firms are talking about are droughts, lack of water, high ambient temperatures.
Randall: Even here in the U.S., there are a lot of regions, specifically in the Southwest, where it's not humid but there are extremely high ambient temperatures. We have customers in the Middle East, we have customers in Southeast Asia, where it's also hot, but also humid. We see a lot of condensation that comes out of air compressors.
With our engineering systems, we mathematically model temperature simulation, what we can see in high ambients, what we can see in high humidities. Then, we can go in and size components and coolers and fans to ensure we're meeting peak performance at high ambients.
Smith: Are you finding customers and engineering firms using your products for high ambient temperatures so they don't have to use a water-cooled air compressor?
Randall: It depends. We have some customers in remote locations that don't have good access to water. In the Middle East, they like the air-cooled just because water is a scarcity. They may not have the cooling towers, they may not have the industrial water to be able to run through a system to be able to cool. We know it's important. We know there's also some performance differences between water- and air-cooled, but we think that is a valuable feature.
We also have remote cooling. We have remote cooler packs that can be pulled away from the air compressor and put into a different location to provide more optimal cooling than an air compressor has. We try to make sure we have the features and functionality that our customers need for their unique applications.
Smith: Can you talk about reducing imbalanced temperature loads? I have to think there's a real benefit to that.
Randall: If you look at cooling plots and diagrams, there are hot spots, there are cold spots. If you look at a traditional radial versus axial fan, radial would be just like a ceiling fan. There's always that cool spot in the center because all the blades are on the outside.
That's where we go back and try to make sure we use modeling to help us understand cooling flow all the way through the coolers themselves. By separating out both air and oil, we have the ability to have different fin types and densities. That way, air can flow through each cooler at its own optimal rate to either cool air or oil, as the oil will come back into the airend for cooling as well as sealing and lubrication. But then air can then go out and cool from an aftercool perspective.
It's really a science of how you want to balance the two coolers to meet different needs. Not too hot, not too cold. We have a standard delta, but we also want to manage oil because it is a critical efficiency component of how the airend operates.
Smith: I see you're still a slow-running 1,800 rpm design. There are other machines out there running a lot faster.
Randall: It's a balance. Do you want to spin a smaller airend faster or a big airend slower? A lot of it depends on what you want for pressure. We sometimes use a smaller air end to get a higher pressure. We won't get the same level of flow.
Think about a garden hose. If you put your thumb over a garden hose, you get pressure. You take your thumb off, you get a lot more flow.
Sometimes you'll see folks go with smaller airends. They'll try to get spin-up faster, but then you can spin too fast and have tip speed issues. We'll look for the optimal size of airend for the displacement of flow we expect to see, then manage pressure up and down with some gearing.
Inside the cabinet, the Sullair TS Series’ two-stage design is clearly visible.
Smith: Creating the TS Series was certainly a collaborative effort. What can you tell us about the team behind it?
Randall: There were thousands of hours of development put into this by the engineering team, but it wasn't just the engineering team. It was also the operations team; how are we going to build this? What does it look like? How do we make sure we have great repeatable processes and control plans in place through sourcing and selecting strategic partners for supply?
The engineering team responsible for the Sullair TS Series. Standing left to right: Alan Barth, Senior Engineer; Don Weinkauf, Senior Designer; Mike Graves, Engineering Manager; Comlan Fandohan, Engineer; Constantin Oproiu, Senior Designer; Ben Oudhuis, Engineer; Nate Heiermann, Senior Designer; Zhenbi Su, Senior Engineer; Don Low, Principal Engineer; Jon Batdorff, Senior Engineer; Eric Noble, Senior Designer. Seated, Abram Valencic, Senior Engineering Manager.
Smith: What’s the latest with Hitachi Air Global Power? You’re an employment powerhouse in Michigan City, right?
Randall: We're the second- or third-largest employer in the county. Sullair was founded here. Sullair was acquired by Hitachi in 2017. We changed our name last year to Hitachi Global Air Power because we represent the Sullair brand, the Hitachi brand, a joint venture brand in China and the Champion brand in Australia.
We've added over 80,000 square feet since the acquisition. We've done some things from a workflow integration strategy allowing us to have better control of cost, quality and delivery. We've hired over 100 incremental people in the ops area to be able to build our products.
Michigan City is the hub. Most all of our machining for rotors is done here. We're working more with our sister facilities in Japan and China on how we can distribute some things differently, exercising our global footprint to better serve customers in those regions.
Hitachi Global Air Power Headquarters in Michigan City, Indiana.
Smith: So the TS is almost like your second giant step after the LS, Sullair’s line of lubricated single-stage rotary screw air compressors that debuted a redesigned air end and used fewer parts.
Randall: Yes, and I think we have more steps to come.
Images courtesy of Hitachi Global Air Power.
For more information, visit https://www.hitachiglobalairpower.com.
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