Top OEMs for Blowers

1. Introduction

In the context of municipal and industrial water and wastewater treatment, aeration blowers represent the single most critical active component in the biological treatment process. They serve as the “lungs” of the plant, delivering the necessary oxygen to microorganisms within activated sludge basins, membrane bioreactors (MBR), and aerobic digesters. From an energy standpoint, blowers are the dominant consumer, typically accounting for 40% to 75% of a wastewater treatment plant’s (WWTP) total electrical energy consumption. Consequently, the selection of the Original Equipment Manufacturer (OEM) and the specific blower technology has a disproportionate impact on the facility’s 20-year lifecycle cost, operational stability, and regulatory compliance.

The engineering landscape for blowers has shifted dramatically over the last two decades. Historically, the industry relied on robust, constant-speed positive displacement (PD) lobe blowers or multistage centrifugal blowers with inlet throttling. While reliable, these technologies often operated at low wire-to-air efficiencies. Today, driven by stringent nutrient removal regulations (requiring precise dissolved oxygen control) and sustainability mandates to reduce carbon footprints, the market has moved toward high-speed turbo blowers, hybrid rotary screw technologies, and advanced control integration.

The applications for this equipment extend beyond simple aeration. Blowers are utilized for air scouring in filtration backwash cycles, pneumatic conveying of lime and grit, channel mixing to prevent solids deposition, and digester gas handling. Each application presents unique thermodynamic and mechanical challenges. For instance, an aeration blower must handle significant turndown capabilities to match diurnal flow patterns, whereas a scour blower typically operates in short, high-intensity bursts.

For consulting engineers and utility decision-makers, the OEM selection process is not merely about comparing nameplate horsepower. It involves evaluating the manufacturer’s ability to provide accurate performance curves (verified by standards such as ASME PTC 10 or ISO 1217), the robustness of their packaging (enclosures, cooling, filtration), and the long-term viability of their service network. The OEMs discussed in this article—Kaeser, Aerzen, Excelsior Blower Systems, Lone Star Blowers, and Absolute Blower & Vacuum—represent the specific cohort of manufacturers relevant to this equipment category. Their selection impacts everything from the noise levels in the blower room to the stability of the biological process during peak loading events.

2. How to Select This Process Equipment

Selecting the correct blower technology and OEM requires a rigorous engineering approach that balances capital constraints with operational realities. The following sections detail the technical criteria that must be evaluated during the design and specification phase.

Process Function and Performance Requirements

The primary engineering definition for a blower application is the intersection of required airflow (Standard Cubic Feet per Minute, SCFM) and discharge pressure (PSIG). However, in wastewater applications, these variables are dynamic.

• Airflow Demand: The biological oxygen demand (BOD) and ammonia load vary throughout the day. A blower system must be sized for the peak hour demand but must also operate efficiently at minimum flows (often 30-40% of peak). OEMs must demonstrate efficiency across the entire “turndown” range, not just at the design point.
• Pressure Requirements: Discharge pressure is a function of static head (depth of the diffuser) plus dynamic losses (friction in piping, losses across valves/diffusers). Engineers must account for system curve migration; as diffusers foul over time, backpressure increases. The selected blower must have enough pressure capability to overcome this fouling without entering a surge condition (for centrifugal/turbo units) or exceeding temperature limits (for PD units).

Technology Classification and Hydraulics

Engineers typically choose between Positive Displacement (PD) and Dynamic (Centrifugal) technologies.
Positive Displacement (Lobe and Screw): These machines move a fixed volume of air per rotation. They are “constant volume, variable pressure” machines. They are exceptionally stable against varying backpressure but traditionally less efficient than dynamic blowers. Modern “screw” designs have significantly closed the efficiency gap.
Dynamic (Multistage Centrifugal and High-Speed Turbo): These impart kinetic energy to the air and convert it to pressure. They are “variable volume, constant pressure” machines. They offer high peak efficiency but are sensitive to changes in inlet temperature and discharge pressure. Turbo blowers, utilizing air foil or magnetic bearings, eliminate oil and mechanical friction, offering the highest tier of efficiency.

Materials of Construction and Packaging

The bare shaft blower is only one part of the system. The “package” provided by the OEM is often where failures occur.

• Enclosures: Sound attenuation is critical. Municipal specs often require <75 dBA or <80 dBA at 1 meter. The enclosure design must allow for adequate heat rejection to prevent VFD or motor overheating.
• Filtration: High-speed turbo blowers are intolerant of particulate matter. OEMs must supply dual-stage filtration systems to protect the tight tolerances of the impellers.
• Coatings: For wastewater environments, the presence of Hydrogen Sulfide (H2S) necessitates corrosion-resistant coatings on enclosures and, in some cases, specific coating on the impellers or rotors if the inlet air is drawn from a corrosive environment.

Integration with Upstream and Downstream Processes

The blower system does not operate in a vacuum. It must integrate seamlessly with the Master Control Panel (MCP) and the Dissolved Oxygen (DO) control system.

• Control Logic: The OEM should provide a local controller capable of “Most Open Valve” logic optimization. This ensures that the blowers generate only enough pressure to satisfy the zone with the highest head loss, minimizing energy waste.
• Surge Protection: For centrifugal and turbo technologies, the OEM’s control system must actively monitor the surge line and open blow-off valves if the operating point approaches instability.

Energy Efficiency and Operating Cost

Wire-to-Air efficiency is the only metric that matters. This metric accounts for losses in the intake filter, the motor, the frequency converter (VFD), the compression element, and the discharge silencer. Engineers should require certified performance curves based on site conditions (elevation, ambient temperature, relative humidity), not just standard conditions. A deviation of 10°F in ambient temperature can significantly alter the mass of oxygen delivered by a volume of air, affecting biological treatment.

Operations and Maintenance Impacts

Maintenance Access: Blower rooms are often tight. OEMs must design packages where oil changes, filter replacements, and belt tensioning (if applicable) can be performed from the front or one side.
Oil vs. Oil-Free: Air-bearing and magnetic-bearing turbo blowers are oil-free, removing a maintenance stream. However, if the electronics fail, they are not field-repairable. PD and Screw blowers require oil changes but are mechanically repairable by general plant staff or local millwrights.

Common Failure Modes

• Overheating: Caused by clogged inlet filters or poor room ventilation.
• VFD Failure: Harmonics or poor power quality can destroy blower drives. Line reactors or active harmonic filters are recommended.
• Surge (Centrifugal): Operating below the minimum flow for the pressure conditions causes violent flow reversal, damaging impellers.
• Belt Slippage (PD): Improper tensioning leads to efficiency loss and belt failure.

Lifecycle Cost Considerations

The purchase price of a blower usually represents less than 10-15% of its 20-year lifecycle cost. Energy consumption represents 80% or more. Engineers should perform a Net Present Value (NPV) analysis using the specific load profile of the plant (hours spent at minimum, average, and peak flows) rather than assuming operation at a single design point.

3. Comparison Table

The following table contrasts the five permitted OEMs based on their primary engineering focus, typical technology offerings, and best-fit applications. Engineers should use this matrix to align the specific requirements of a project (e.g., high efficiency vs. rough-duty reliability) with the manufacturer’s core strengths.

OEM Name	Typical Applications	Engineering Strengths	Limitations	Maintenance Considerations
Kaeser	Aeration, Air Scouring, Pneumatic Conveying, Filter Backwash	Highly integrated packages (“Compaq” series); Strong focus on rotary screw technology for efficiency; Plug-and-play internal controllers (Sigma Control).	Primarily focused on PD and Screw technologies; less presence in large-scale centrifugal/turbo markets compared to others.	Standard oil changes and belt maintenance; intuitive controller simplifies diagnostics.
Aerzen	High-Efficiency Aeration, Industrial Wastewater, Biogas	Pioneers of “Hybrid” rotary lobe/screw technology (Delta Hybrid); Broad portfolio including PD, Hybrid, and Turbo; Strong rental/interim fleet.	Premium technology often comes with a higher initial capital cost; Turbo units require specialized service.	Turbo units are oil-free (air foil bearings); Hybrid and PD units require oil maintenance but offer extreme durability.
Excelsior Blower Systems	Custom Municipal Applications, High-Pressure Conveying, Retrofits	Exceptional custom packaging capabilities; Willingness to engineer non-standard footprints or enclosures; Integration of robust PD blocks (e.g., Gardner Denver).	Acts primarily as a packager/system integrator rather than a manufacturer of the core air-end; lead times can vary based on component availability.	Dependent on the core blower block selected; excellent access design for custom enclosures.
Lone Star Blowers	Large Municipal Aeration, Industrial Process, Petrochemical	Specialists in Centrifugal and Turbo technologies; “Gearless” and “Geared” Turbo options; Strong capability in retrofitting legacy multistage centrifugal brands.	Less focused on small-scale PD applications; High-tech turbo units require sophisticated operator training.	Varies significantly by technology (Oil-free for Turbo vs. Oil lube for Multistage); Remote monitoring capabilities are strong.
Absolute Blower & Vacuum	Small to Mid-Size Municipal, Vacuum Systems, Industrial	Flexible packaging solutions; Strong focus on positive displacement and vacuum applications; Responsive support for niche configurations.	Smaller global footprint compared to major multinational conglomerates; Portfolio more focused on PD/Vacuum than high-speed turbo.	Standard mechanical maintenance (bearings, seals, oil); Simplified designs favor ease of in-house repair.

4. Top OEM Manufacturers

Kaeser

Kaeser Compressors is a globally recognized name in compressed air and blower systems. In the municipal water sector, they are best known for their packaged blower solutions that emphasize ease of installation and “Sigma Profile” efficiency.
Technology Focus: Kaeser’s primary strength lies in Rotary Lobe (Omega) and Rotary Screw blowers. They have been instrumental in transitioning the market from standard two-lobe blowers to three-lobe designs (for reduced pulsation) and eventually to rotary screw blowers. The screw blower compresses air internally (unlike the external compression of a lobe blower), which results in significant adiabatic efficiency gains, often in the range of 15-25% energy savings over conventional lobes.
Engineering & Packaging: Kaeser distinguishes itself with the “Compaq” system design. These units are shipped as fully enclosed, pre-piped, and pre-wired packages. The engineering philosophy is “plug-and-play,” reducing contractor error during installation. Their integrated Sigma Control 2 unit manages machine health, communication (SCADA/Modbus), and protects the unit from operating outside its safe envelope.
Best Fit: Kaeser is an excellent specification choice for facilities seeking high efficiency in the low-to-medium pressure range (up to 15 PSIG) without the complexity of high-speed turbo blowers. They are also highly favored for air scour applications where reliability and start/stop durability are paramount.

Aerzen

Aerzen is a German-headquartered manufacturer with a deep history in positive displacement technology, credited with manufacturing the first positive displacement blower in Europe. Today, they offer perhaps the widest breadth of technologies under a single brand, allowing for “technology neutral” application advice.
Technology Focus: Aerzen’s portfolio includes the “Delta Blower” (standard PD), the “Delta Hybrid” (a twisted lobe compressor that bridges the gap between lobe and screw), and the “Aerzen Turbo” (high-speed turbo blowers with air foil bearings). The Delta Hybrid is particularly notable for engineers; it combines the robustness of a PD machine with the internal compression efficiency of a screw, making it ideal for the 8-12 PSI range typical of aeration tanks.
Engineering & Packaging: Aerzen emphasizes “Generation 5” packages that focus on noise reduction and compact footprints. Their Turbo blowers utilize air foil bearings, which eliminate oil and separate the mechanical wear components from the air stream. A unique engineering strength is their ability to control hybrid and turbo blowers in the same manifold, using the Turbo for base load efficiency and the Hybrid for peak trimming and turndown capability.
Best Fit: Aerzen is a top-tier choice for medium-to-large municipal plants aiming for net-zero energy goals. Their ability to mix-and-match technologies (Performance³ concept) allows engineers to optimize the efficiency curve across the entire flow range of the plant.

Excelsior Blower Systems

Excelsior Blower Systems operates differently from the massive conglomerates. As a premier packager and system integrator, they focus on the engineering of the complete blower assembly rather than just the manufacturing of the compression element.
Technology Focus: Excelsior builds systems around proven blower blocks, primarily Gardner Denver positive displacement and helical screw blowers. Their expertise lies in the ancillary engineering: sizing the motor, selecting the optimal V-belt or direct drive arrangement, designing the discharge silencers to meet strict acoustic specifications, and fabricating heavy-duty bases.
Engineering & Packaging: This OEM is frequently selected when “off-the-shelf” does not work. If a consulting engineer needs a blower to fit into a non-standard physical space, requires stainless steel enclosures for a corrosive environment, or mandates specific instrumentation brands to match plant standards, Excelsior excels. Their “Gardner Denver” heritage ensures that the core mechanical components are readily serviceable and parts are widely available.
Best Fit: Best suited for retrofit projects with tight spatial constraints, industrial wastewater treatment plants requiring rugged customized solutions, and municipalities that prefer the serviceability of traditional PD blowers packaged to modern noise and vibration standards.

Lone Star Blowers

Lone Star Blowers has carved out a significant niche by focusing on dynamic compression technologies—specifically centrifugal and turbo blowers. They are aggressively positioned as the experts in large-volume air movement.
Technology Focus: Lone Star offers a comprehensive range of centrifugal technologies: Multistage Centrifugal (cast iron, typically constant speed with throttling), Geared Turbo (integrally geared, high efficiency), and Gearless Turbo (high-speed, magnetic or air bearing). They are one of the few OEMs that can supply a new gearless turbo for a greenfield plant while simultaneously supplying a drop-in replacement part for a 40-year-old Hoffman or Lamson multistage blower.
Engineering & Packaging: Their engineering strength is in high-volume, low-pressure applications. The “GL-Series” gearless turbo blowers feature an advanced control system that actively manages the surge line, maximizing the turndown range. They also manufacture their control panels in-house, allowing for custom logic integration that many other turbo manufacturers cannot accommodate.
Best Fit: Lone Star is the preferred OEM for large municipal treatment plants (10 MGD+) where the energy savings of turbo technology are most pronounced. They are also the go-to solution for plants looking to rehabilitate existing multistage centrifugal blowers without changing the piping footprint.

Absolute Blower & Vacuum

Absolute Blower & Vacuum is a specialized provider focusing on the smaller to mid-sized market and specific industrial applications. They offer a high degree of flexibility and personal engineering support that can be lost with larger entities.
Technology Focus: Their core competency revolves around Positive Displacement blowers (Roots-type) and vacuum packages. They often utilize high-quality blower blocks and integrate them into cost-effective, reliable packages. They are particularly adept at handling applications that involve both pressure and vacuum, such as pneumatic conveying loops or specialized degassing processes.
Engineering & Packaging: Absolute focuses on accessibility and simplicity. Their packages are designed to be easily maintained by plant staff without proprietary tools. They minimize the use of complex, “black box” electronics in favor of robust, industry-standard components.
Best Fit: Ideal for smaller municipal plants, package treatment plants, and industrial facilities where simplicity, low capital cost, and ease of maintenance are prioritized over the absolute highest tier of wire-to-air efficiency.

5. Application Fit Guidance

Not every blower fits every application. Engineers must match the OEM’s strength to the facility type.

Municipal Water (WTP)

In water treatment, blowers are primarily used for filter backwashing (air scour). This is an intermittent, high-intensity application.
Recommended Fit: Kaeser and Excelsior Blower Systems are strong contenders here. The application favors Positive Displacement (PD) or Screw blowers because backpressure varies significantly as the water level changes in the filter during the backwash. PD blowers handle this pressure fluctuation more stably than centrifugal units.

Municipal Wastewater (WWTP) – Large Facilities (>10 MGD)

Aeration energy is the driver. Small efficiency gains yield massive operational savings.
Recommended Fit: Lone Star Blowers and Aerzen. The turbo and hybrid technologies offered by these OEMs provide the necessary turndown and wire-to-air efficiency. Lone Star’s large centrifugal capabilities are also vital for plants requiring 10,000+ SCFM per unit.

Municipal Wastewater (WWTP) – Small to Medium Facilities (<5 MGD)

Operations staff may be limited; simplicity and reliability often trump marginal efficiency gains.
Recommended Fit: Kaeser, Absolute Blower & Vacuum, and Aerzen. Kaeser’s screw blowers offer a “sweet spot” of high efficiency with the mechanical simplicity of a rotary machine. Absolute offers cost-effective, repairable solutions for smaller budgets.

Industrial Wastewater

Industrial streams vary wildly in temperature, corrosivity, and loading.
Recommended Fit: Excelsior Blower Systems and Absolute Blower & Vacuum. Industrial clients often need custom stainless steel enclosures, explosion-proof motors (Class 1 Div 2), or specialized seals. Excelsior’s packaging flexibility is a major asset here.

Retrofit vs. Greenfield

• Greenfield: Aerzen or Lone Star (Turbo/Hybrid) to minimize building footprint and electrical infrastructure.
• Retrofit: Excelsior or Lone Star. Excelsior can custom-build bases to match existing concrete pads. Lone Star can drop a new centrifugal unit into the space of a defunct legacy unit with minimal piping changes.

6. Engineer & Operator Considerations

Installation and Commissioning

Engineers must specify that the OEM provides on-site startup services. For turbo blowers, commissioning is complex; the surge line must be mapped in the field under actual load conditions. For PD blowers, laser alignment of V-belt sheaves or direct couplings is mandatory to prevent premature bearing failure.
Note: Ensure the blower room has adequate intake louvers. A common failure in new installations is starving the blowers of air, creating a vacuum in the room that reduces performance and overheats motors.

Maintenance Access and Spare Parts

Kaeser and Aerzen generally rely on proprietary parts for their advanced screw and turbo machines. While their supply chains are robust, operators should keep critical spares (sensors, controller boards, oil filters) on the shelf.
Excelsior and Absolute often use components (motors, belts, valves) that can be sourced from local industrial supply houses, which is a significant advantage for plants in remote locations.

Operational Lessons Learned

• The Check Valve: Always install a high-quality, fast-acting check valve on the discharge. If a blower stops and backflow spins it in reverse, a restart will destroy the machine immediately.
• VFD Harmony: When retrofitting VFDs to existing PD blowers (like those from Excelsior or Absolute), ensure the motor is “Inverter Duty” and that the minimum speed is set high enough to maintain splashing lubrication inside the blower gearbox.
• Heat Rejection: Turbo blowers (Lone Star, Aerzen) are sensitive to ambient heat. If the electrical room or blower room exceeds 104°F (40°C), the VFDs may trip. Ducting the discharge air from the cooling fans outside the building is a best practice.

Long-Term Reliability Risks

High-speed turbo blowers have a distinct “end of life” for their electronics and bearing cores, often requiring a factory exchange after 7-10 years. In contrast, robust PD blowers (Kaeser, Excelsior) can often be rebuilt indefinitely, provided the rotors are not damaged. Engineers must weigh the 20% energy savings of a turbo against the potential specialized replacement costs down the road.

7. Conclusion

The selection of a blower OEM is a pivotal decision in the design of water and wastewater systems. It is not a commodity purchase. The choice dictates the facility’s energy profile, maintenance burden, and operational flexibility for decades.

Kaeser and Aerzen represent the pinnacle of European engineering efficiency, offering integrated packages and advanced screw/turbo/hybrid technologies ideal for energy-conscious facilities. Lone Star Blowers dominates the high-volume dynamic blower market, offering critical solutions for large plants and centrifugal retrofits. Excelsior Blower Systems serves the vital role of the custom integrator, providing robust, specification-heavy packages for difficult applications. Finally, Absolute Blower & Vacuum provides essential support for the small-to-mid market and specialized vacuum needs with a focus on simplicity and serviceability.

Engineers should move beyond simple datasheet comparisons and evaluate the “system” offered by the OEM—including control logic, thermal management, and aftermarket support—to ensure the lungs of the treatment plant breathe efficiently for years to come.

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