Fine particles captured in the duct
Particles in the supply air are electrically charged and held on a washable collector cell.
SMAY – we provide comfort and safety for buildings
Clean supply air shouldn’t come with high running costs. KEF is for designers and installers who want better indoor air without the recurring cost of filter media. It captures fine particles electrostatically on a washable collector cell, runs at approx. 35–40 Pa at nominal airflow and draws just 3–25 W.
Particles in the supply air are electrically charged and held on a washable collector cell.
Approx. 35–40 Pa at nominal airflow (clean, with the optional pre-filter), so the fan has less to overcome.
The collector cell is washed every 3–6 months and is designed for around 10 years of use.
Low electrical consumption from 600 to 5,400 m³/h nominal airflow.
Ozone tested – Lublin University of Technology, 2026
Outdoor air carries fine particulate matter into buildings all year round, with seasonal peaks such as pollen in spring.
Europeans spend around 85–90% of their time indoors, and 50–90% of outdoor PM2.5 can find its way inside.
Fibrous filters keep working only if their media are replaced regularly – a recurring cost every few months. In buildings with many occupants and high airflows, such as offices, schools and public buildings, the effect compounds:
Europe’s air is improving – but most city dwellers still breathe fine-particle levels above WHO guidelines.
KEF (In-Duct Electrostatic Filter) is installed in rectangular or circular supply ducts and works on SMAY iNAC (Intelligent Nano Air Cleaner) electrostatic technology. It captures particles without fibrous filter media, with low pressure drop, no replacement elements and no ozone detected in laboratory tests.
Electrostatic capture — particles are charged and attracted to the collector cell.
Low energy use — 3–25 W electrical consumption, depending on size.
No ozone detected — no ozone was detected downstream of KEF in 24-hour tests at Lublin University of Technology.
Washable collector cell — washed every 3–6 months and designed for around 10 years of use – no replacement media.
Low pressure drop — approx. 35–40 Pa at nominal airflow with the optional pre-filter, 20–23 Pa without (clean filters).
Optional pre-filter — retains coarse particles; cleaned with a vacuum cleaner.
Easy access — cells are withdrawn through the access door; the KEF-P tool helps on 1,000–1,500 mm widths.
14 sizes — from 600 to 5,400 m³/h nominal airflow; circular transitions Ø160–Ø400 for KEF200–KEF500.
Air passes through KEF in three stages:
01
Air passes through the charging frame, where particles pick up an electric charge.
02
Following Coulomb’s law, the charged particles are attracted to the collector cell and held there – much as a magnet attracts metal.
03
Captured particles stay on the collector cell until it is washed – every 3–6 months – and refitted.
Cleaned air continues through the ductwork to the room.
Fibrous filters hold particles in their media, and the media end up as waste. KEF holds them on a washable cell instead – the cell is cleaned, not replaced.
Not all filtration works the same way. Here is how KEF compares with a typical ePM1 bag filter in supply air.
| Criterion | SMAY KEF | Typical ePM1 bag filter |
|---|---|---|
| How particles are held | On a washable collector cell (electrostatic) | In fibrous filter media |
| Pressure drop, clean, at nominal airflow | approx. 35–40 Pa¹ | approx. 80–135 Pa² |
| Maintenance | Cell washed every 3–6 months | Replaced when the final pressure drop is reached – up to 100 Pa above initial (EN 13053) |
| Replacement media | None – cell designed for around 10 years | New filters at every change |
| Filter waste | No used media | Used filters for disposal |
| Electrical consumption | 3–25 W | None |
¹ SMAY laboratory measurements, clean filters, with the optional pre-filter. ² Published data of European filter manufacturers. KEF’s filtration efficiency is not classified to ISO 16890; this table does not compare filtration efficiency.
| Model | Nominal airflow (m³/h) | Δp with pre-filter (Pa) | Δp without pre-filter (Pa) | Maximum airflow (m³/h) | Δp at maximum, with / without (Pa) |
|---|---|---|---|---|---|
| KEF200 | 600 | ≈ 35 | ≈ 22 | 1,000 | ≈ 76 / ≈ 45 |
| KEF400 | 1,440 | ≈ 40 | ≈ 23 | 2,400 | ≈ 92 / ≈ 51 |
| KEF900 | 3,240 | ≈ 37 | ≈ 20 | 5,400 | ≈ 89 / ≈ 47 |
| KEF1500 | 5,400 | ≈ 36 | ≈ 20 | 9,000 | 56 / 30 at approx. 7,100 m³/h |
Measured on a ducted test rig with clean filters; values at the listed airflows interpolated from the measurements. Curves for all 14 sizes are in the data sheet.
Assuming continuous 24/7 operation, here is how the running costs compare in a worked example: one KEF900 against one ePM1 bag filter (592 × 592 × 600 mm) at 3,400 m³/h.
| Cost item | ePM1 bag filter | KEF900 |
|---|---|---|
| Energy (fan + device) | 1,310 kWh/year → €241 | 604–639 kWh/year → €111–117 |
| Filter media | €61–122 per year | €0 (washable cell) |
| Total per year | €302–363 | €111–117 |
| Total over 5 years | €1,510–1,815 | €555–585 |
Assumptions: 8,760 h/year; fan and drive efficiency 0.6; electricity €0.1837/kWh (EU average for non-household consumers, second half of 2025, Eurostat; national averages about €0.07–0.26/kWh). Clean-filter pressure drop: KEF900 approx. 40 Pa with pre-filter (SMAY laboratory), bag filter 95 Pa (published manufacturer data, ePM1 50%). Bag filter €61 net (average of three ePM1/F7 filters from European distributors, October 2026), replaced 1–2 times a year. KEF900 electrical consumption 6–10 W. Not included: purchase and installation price, labour, filter disposal. This example compares running costs only, not filtration efficiency.
≈ 50%
lower energy use in this example, comparing clean filters.
€0
spent on replacement filter media.
KEF fits wherever supply air needs fine-particle capture and running costs matter.
Offices, shopping centres, public buildings and airports – high footfall and high airflows. KEF in the supply ductwork adds particle capture with low pressure drop and minimal servicing.
Nurseries, schools and universities – long occupied hours and tight maintenance budgets. The collector cell is cleaned on site instead of being re-stocked.
KEF200–KEF500 with KEF-R transitions connect to circular ductwork. KEF itself needs no replacement media.
Server rooms and other technical spaces where low maintenance matters, subject to the project’s filtration requirements.
Certification schemes assess buildings, not products. KEF’s low pressure drop and washable cell can support a project’s energy and maintenance strategy; check filtration-related credits with the assessor.
| Parameter | Value |
|---|---|
| Technology | Electrostatic (SMAY iNAC) |
| Installation | In-duct, supply air; rectangular ducts, circular via KEF-R |
| Range | 14 sizes, 200 × 600 to 1,500 × 600 mm |
| Airflow | 600–5,400 m³/h nominal; 1,000–9,000 m³/h maximum |
| Pressure drop | approx. 35–40 Pa at nominal airflow (clean, with pre-filter) |
| Power supply | 230 V AC, 50 Hz; 3–25 W |
| Protection | IP40 |
| Casing | Galvanised steel |
| Maintenance | Collector cell washed every 3–6 months; designed for around 10 years of use |
| Accessories | KEF-R transitions Ø160–Ø400; KEF-P extraction tool (1,000–1,500 mm widths) |
| Ozone | Not detected (Lublin University of Technology, April 2026) |
FAQ
No ozone was detected. In tests by Lublin University of Technology (April 2026) – three 24-hour runs of continuous operation at 25 °C and 50% RH, with no carbon filter fitted – the ozone concentration downstream of KEF did not exceed 0.00 ppm. The laboratory used its own method, aligned with the requirements of EN 60335-2-65.
Yes. Isolate the power supply, open the access door, withdraw the collector cell, wash it and let it dry fully before refitting. The optional pre-filter is cleaned with a vacuum cleaner.
At nominal airflow, approx. 35–40 Pa with the optional pre-filter and 20–23 Pa without it (clean filters). Check the fan duty point against the pressure drop curves in the data sheet.
High-voltage parts sit inside the casing behind the access door. Always isolate the power supply before opening it.
KEF captures fine particles electrostatically. Its filtration efficiency is not classified to ISO 16890; where a specification calls for a classified filter stage, agree the arrangement with the project’s designer – we are happy to advise.
KEF is designed to capture particles. For VOCs and odours, use a gas-phase filter stage, such as activated carbon.
Every 3–6 months, depending on outdoor air quality, occupancy and operating hours – with no new filters to buy at each service.
KEF is a duct-mounted unit in 14 sizes for rectangular ducts, with KEF-R transitions for circular ducts. Check the fan duty point against the pressure drop curves in the data sheet.
Certification schemes assess buildings, not products. KEF’s low pressure drop and washable cell can support a project’s energy and maintenance strategy; check filtration-related credits with the assessor.
Yes, for ozone: Lublin University of Technology detected no ozone downstream of KEF (April 2026). Pressure drop was measured in SMAY’s laboratory on a ducted test rig.
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