In-Duct Bipolar Ionisation for AHUs & Whole-Building HVAC Systems
Install PurAire bipolar ionisation inside central air-handling units and supply ducts to provide centralised treatment across the areas served by the AHU.
A property with one central AHU may be treated from a single central location, while larger buildings with several AHUs will normally require appropriate treatment at each air-handling system.
What Is In-Duct Bipolar Ionisation?
An AHU bipolar ionisation system is installed directly inside an air-handling unit or supply-air duct. The HVAC airflow carries positive and negative ions from the high-efficiency ionisation tubes into the rooms and zones served by that air-handling system, proactively neutralising pathogens, volatile organic compounds (VOCs), and stubborn odours at the source.
Why Use Central In-Duct Bipolar Ionisation
The HVAC system is already moving air throughout the building — so it is an ideal place to introduce centralised air treatment.
Installing bipolar ionisation inside an AHU or supply duct allows the building’s existing airflow to distribute ions throughout the rooms and zones served by that system.
This can provide continuous, silent treatment for persistent tobacco, food, body, musty and other occupancy odours without placing separate equipment in each room.
For larger properties with multiple AHUs, the system can be scaled by selecting the appropriate SG-BPI model for each AHU’s airflow and the areas it serves.
Send us your AHU airflow, duct dimensions, and the areas served. We’ll recommend the appropriate PurAire SG-BPI configuration.
Which SG-BPI Model Fits My AHU?
Airflow-switch, HVAC fan interlock and BMS/MODBUS control options are available depending on model and configuration. Selected PurAire fixed in-duct models are UL 2998 certified for zero ozone emissions; refer to the individual model page and applicable certificate for certification details.
PurAire SG-BPI-1
A single ionisation tube for compact ductwork and smaller air handling systems. Eliminates odours and airborne microorganisms in the supply air before it reaches the space.
The SG-BPI-1 is available with both vertical tube configuration (shown) or 1 horizontal tube.
- Best for small-to-medium office split-ducts, individual boutique shops, and compact AHU zones.
PurAire SG-BPI-2
Dual-tube configuration for smaller commercial AHUs and supply ducts where greater ionisation capacity than a single-tube model is required.
The SG-BPI-2 is available with both vertical tube configuration (shown) or 2 horizontal tubes.
- Best for small-to-medium office split-ducts, individual boutique shops, and compact AHU zones.
PurAire SG-BPI-4
Four-tube configuration designed for medium commercial AHUs and supply-air systems, with adjustable ionisation output.
The SG-BPI-4 is available with both vertical tube configuration (shown) or 4 horizontal tubes
- Best for open-plan offices, restaurants, schools, medical waiting wings, and medium commercial buildings.
PurAire SG-BPI-5
A heavy-duty, multi-tube ionisation system built for rigorous commercial and institutional airflow requirements. Provides continuous ionisation and odour reduction across larger ventilation networks.
The SG-BPI-5 is available with both horizontal tube configuration (shown) or 5 vertical tubes
- Best for open-plan offices, restaurants, schools, medical waiting wings, and medium commercial buildings.
PurAire SG-BPI-6
Designed for large-scale central air systems, the SG-BPI-6 delivers high-density ion output to purify vast volumes of circulating air. It is ideal for facilities dealing with high occupancy rates and heavy daily air quality demands.
The SG-BPI-6 is available with both vertical tube configuration (shown) or 6 horizontal tubes
- Best for large commercial complexes, hotel ventilation mainlines, shopping malls, and multi-story towers.
PurAire SG-BPI-8
An ultra-capacity in-duct unit featuring an expanded array of ionisation tubes for massive commercial and industrial air-handling units (AHU) up to 20,400 m³/h and 1,500 m².
The SG-BPI-8 offers an expanded tube array for large commercial and industrial air handling units, where the volume of air moved needs more ion output than the mid-range units provide.
The SG-BPI-8 is available with both horizontal tube configuration (shown) or 8 vertical tubes.
- Best for large commercial complexes, hotel ventilation mainlines, shopping malls, and multi-story towers.
PurAire SG-BPI-9
Engineered specifically for massive industrial ventilation systems and high-flow central ducts, the SG-BPI-9 tackles heavy-duty air purification challenges, neutralizing heavy pollutants and large volumes of airborne contaminants.
It is designed for high-flow commercial and industrial AHUs, with a published airflow rating of 28,900 m³/h and coverage up to 2,000 m² and is available with both horizontal and vertical tube configurations.
- Best for industrial manufacturing plants, massive public transit hubs, and enterprise-scale building ventilation systems.
PurAire SG-BPI-12
The ultimate powerhouse of the SG-BPI series, featuring a maximum-density tube configuration built for the largest commercial and industrial central air networks.
The SG-BPI-12 is the highest-tube-count model in the current SG-BPI range, with published adaptive airflow up to 36,000 CFM / 61,000 CMH and an application area up to 2,500 m². It is available with vertical or horizontal tube configurations.
- Best for industrial manufacturing plants, massive public transit hubs, and enterprise-scale building ventilation systems.
How We Size an SG-BPI System
AHU airflow in CFM or CMH is one of the most important sizing inputs. Additionally, duct dimensions, areas served, occupancy, tube configuration, and the particular odour or IAQ problem should always be carefully considered to ensure optimal performance.
FCU vs AHU Treatment: Which Do You Need?
FCU Ionisers
Normally treat an individual room or local zone directly through its own room fan coil unit (ideal for individual hotel guest rooms or private offices).
AHU In-Duct Systems (SG-BPI)
Designed for larger air-handling units and supply ducts serving multiple rooms or entire building zones.
Frequently Asked Questions
An AHU bipolar ioniser is installed inside an air-handling unit or supply air duct. The HVAC airflow carries positive and negative ions from the ionisation tubes into the rooms and zones served by that air-handling system.
It depends on the building’s HVAC design. One correctly sized ioniser can provide central treatment across the areas served by one AHU. Buildings with multiple AHUs may require separate ionisation units for each system.
AHU airflow in CFM or CMH is one of the most important sizing inputs. Duct dimensions, areas served, occupancy, tube configuration and the particular odour or IAQ problem should also be considered.
The SG-BPI range is designed for installation in suitable existing air handling
units and supply ducts. Final compatibility depends on available mounting space, airflow, electrical supply and access for servicing.
No. Bipolar ionisation is supplemental air treatment. Normal filtration, ventilation, coil and drain maintenance, and source control remain necessary.
An FCU ioniser normally treats an individual room or local zone through its fan coil unit. An SG-BPI in-duct system is designed for larger AHUs and supply ducts serving multiple rooms or building zones.
That set is excellent for long-tail and AI-search intent without duplicating the detailed product-page FAQs.
For larger buildings, bipolar ionisers can be installed in central air-handling units or HVAC supply ducts so that the existing ventilation system distributes ions through multiple occupied areas.
They are typically installed inside an AHU or main supply-air duct where there is sufficient airflow and appropriate access for mounting and maintenance. Final placement should be based on HVAC design and airflow.
In many cases, yes. Retrofit suitability depends on duct dimensions, airflow, electrical supply, access and the number of air-handling systems serving the building.
Sizing should be based primarily on HVAC airflow, duct configuration, number of air-handling systems and the areas being served. Large systems may require multiple ionisation tubes or units rather than a single small emitter.
No. Bipolar ionisation is supplemental air treatment. It should work alongside appropriate filtration, outdoor-air ventilation, HVAC maintenance and source control.
Need Help Sizing Your AHU?
Contact Us for a Free On-Site Inspection and Evaluation.
Send us your AHU airflow, duct dimensions, and floor space layout. We’ll recommend the appropriate PurAire SG-BPI configuration.