Industrial Dilution Air Fans & Blowers
Industrial-strength fans designed for compliance, durability, and long-term efficiency.
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Industrial Dilution Air Fan Applications
Combustion-based processes, such as furnaces, boilers, kilns, and incinerators, produce exhaust that must be treated before release. Dilution air fans inject clean ambient air into the contaminated airstream, lowering concentrations of NOx, CO₂, VOCs, and other pollutants to meet emissions standards.
In systems like SCR units, dilution air is added upstream to maintain proper airflow, temperature, and exhaust composition. This ensures consistent environmental performance and reliable operation of downstream pollution-control equipment.
Your airflow, temperature, and system conditions will determine the ideal dilution air fan design and configuration.
Primary Industries for Dilution Air Fans & Blowers
Dilution air systems are critical in industries that generate Volatile Organic Compounds (VOCs), Hazardous Air Pollutants (HAPs), or combustion byproducts requiring treatment. Common applications include:
Power generation:
- Coal-fired plants
- Natural gas power plants
- Biomass and waste-to-energy facilities
Industrial combustion & process heating:
- Boilers & furnaces
- Incinerators & oxidizers
- High-temperature drying & curing systems
General emissions control:
- Chemical processing
- Petrochemical & refining
- Metal processing & foundries
Dilution Air Blower Technology Selection & Specification
With strict EPA emissions standards in place, reliable dilution air systems are essential for maintaining safe, compliant operation across many industrial processes. This makes proper blower selection and specification critical to ensuring long-term reliability and stable performance.
A key part of the specification process is selecting a fan that remains stable across all expected operating points on the fan curve. Because dilution air systems often require variable flow, choosing a fan that operates too far left on the static pressure curve can push the system into surge—an unstable condition that causes vibration, inefficiency, and premature failure.
By selecting a properly sized high-pressure blower, the system maintains stability and efficiency across a wide range of operating conditions, with built-in margin for process fluctuations.
Fan types commonly used in dilution air applications:
- Pressure Blowers
(P##A/B/C/D) - Extreme Pressure Blowers
(XP#S/O) - Backward Curved Low-Volume
(BCLS, BCNS)
Dilution Air Fan Arrangements, Accessories, & Design
Fan design and accessory selection focus on protecting the fan, bearings, and motor while ensuring reliable operation and simplified maintenance. Although dilution air systems are located near high-temperature equipment, the air entering the fan is typically ambient, so standard materials of construction are generally suitable.
Industrial fan arrangements commonly used for dilution air:
Fan arrangements indicate how the motors mount to and drive the fans. For dilution air fans, we typically use direct-drive arrangements, usually Arrangement 4 or Arrangement 8.
Arrangement 4 – Belt Drive with an overhung impeller. The fan and motor mount separately to a unitary base.
Arrangement 8 – Direct Drive with an overhung impeller. The fan shaft is directly coupled to the motor shaft with a flexible coupling.
Fan accessory & design considerations for dilution air fans:
Airflow is commonly controlled using variable frequency drives (VFDs), inlet dampers, or a combination of both. Together, these components modulate system airflow for improved efficiency, better combustion performance, and reduced energy consumption.
In industrial dilution air applications, we often recommend the following accessories:
- Flow Control Options – includes inlet vane dampers, variable frequency drives (VFD), outlet dampers, or a combination, each offering control over airflow volume and pressure
- Actuators and Positioners – automate damper control for precise airflow regulation
- Inlet Filter or Screen – to keep the airstream clean and avoid introducing items that could be harmful to downstream equipment & process
- Inlet Silencer – for noise control
- Inlet Box – if vertical down entry is required for safety
- Vibration Isolators – when foundational mass is insufficient to support fan operation
- Vibration and Temperature Sensors – to monitor bearing and fan health and prevent unplanned outages
- Expansion Joints – absorb thermal movement and vibration between the fan and ductwork
How Dilution Air Fans Work
Industrial dilution air fans introduce controlled amounts of clean, cooler air into hot or contaminated process airstreams to regulate temperature, protect equipment, and ensure safe system operation. The fan pulls in ambient air and forces it into the process flow, where it mixes with high-temperature or high-concentration gases to “dilute” them—reducing heat, lowering concentration, and stabilizing downstream conditions.
In many industrial systems, dilution air fans play a critical role in maintaining safe operating limits, improving combustion efficiency, and protecting equipment from overheating or damage.
Connect with a Dilution Air Fan Expert
Our experienced application engineers are ready to help you find the right fan. Whether you’re replacing an existing unit or designing a new system, we’ll make sure you get a solution that fits your specs, timeline, and budget.
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