Short answer: An electrostatic precipitator, normally shortened to ESP, is an in-line particle-control device. It electrically charges fine grease and smoke particles in kitchen exhaust and attracts them to collector plates. It can materially reduce visible smoke and fine particulate loading, but it is not automatically a complete odour-control system.
Canopy grease filters capture a proportion of larger droplets. Much smaller oil mist and smoke can remain in the air stream and travel into the duct. An ESP is commonly used downstream of the canopy filters to remove more of that particulate load before air reaches a carbon, UV or other gaseous-odour treatment stage. Its performance depends on actual airflow, cell condition, electrical operation and whether air can bypass the collector bank.
Important: This guide explains design questions; it is not a product selection, planning approval or performance guarantee. A competent designer should assess the actual kitchen, air system, discharge and maintenance conditions.
How an ESP collects particles
The ionising section gives airborne particles an electrical charge. The collector section then creates an electric field that attracts those charged particles to metal plates. The collected grease is removed when the cells are cleaned. The process is different from a disposable mechanical filter: the cells are washable, but they still need a disciplined cleaning regime and functioning high-voltage components.
- Canopy filters remove larger grease droplets first.
- The ioniser charges smaller particles carried in the extract air.
- Collector plates retain a proportion of the charged smoke and oil mist.
- Cleaned cells must be refitted in the correct orientation and fully seated.
What an ESP can and cannot treat
An ESP is strongest on particulate matter such as fine grease aerosol and smoke. Many cooking smells are gaseous compounds rather than particles. Removing smoke can make the discharge look cleaner and protect downstream media, but a kitchen with a significant odour risk may still require activated carbon, UV-based oxidation, improved discharge or another site-specific measure.
- Useful for fine grease and visible smoke control.
- May reduce grease deposition downstream when correctly maintained.
- Does not replace the canopy grease filters or duct-cleaning programme.
- Does not prove that gaseous odour has been adequately controlled.
The design information that matters
A model name or claimed percentage is not enough to specify an ESP. The designer needs the measured or calculated airflow, cooking duty, contaminant load, allowed pressure loss, cell face velocity, available electrical supply, control interlock, service space and cleaning arrangement. The selected unit must operate within the manufacturer’s stated airflow range at the real system duty.
- Design airflow and expected operating range.
- Cooking equipment and hours of use.
- Single-pass or multi-pass cell arrangement.
- Pressure drop and fan-duty allowance.
- Safe removal route and wash/cleaning method.
What the observation may be telling you
| Observation | What it may mean | Correct next step |
|---|---|---|
| Heavy visible smoke after the ESP | Cells may be dirty, de-energised, bypassed or outside their airflow range | Check alarms and arrange competent inspection; do not open live equipment |
| Arcing or repeated electrical faults | Contamination, moisture, damaged components or incorrect cell fit may be involved | Isolate through the approved procedure and call the service provider |
| Odour remains but smoke is reduced | The particulate stage may be working while gaseous treatment or dispersion is inadequate | Review the complete treatment train and discharge |
| Airflow falls after a retrofit | Added resistance or an incorrect fan operating point may be reducing capture | Measure system airflow and rebalance the complete system |
| Frequent cell fouling | Upstream grease capture, cooking load or cleaning interval may be unsuitable | Review canopy filters, duty and maintenance frequency |
A practical design and handover workflow
Treat the filtration unit as one component of an air system. A dependable design starts with the cooking process and ends with a maintainable discharge, rather than starting with a catalogue airflow. The following workflow gives the client, designer and installer a shared audit trail.
- Define the source. List every appliance, fuel, cooking method, duty, diversity assumption and operating period. Chargrilling, frying and light reheating do not create the same grease, smoke or odour load. Record the future menu where the tenant is not yet trading.
- Establish the air duty. Calculate the extract volume and capture arrangement, then record the expected operating range. Check make-up air, duct velocity, leakage class, fan curve and the resistance of clean and loaded treatment stages.
- Select the treatment train. State what each stage is intended to remove, the evidence used for selection and the conditions attached to any performance claim. Include bypass sealing, controls, interlocks, alarms and the effect of failure.
- Prove and maintain it. Commission airflow and functions at the installed condition. Give the operator baseline readings, access instructions, cleaning intervals, consumables and a clear trigger for inspection or replacement.
Keep a useful record: Keep the approved drawing, design airflow, fan duty, clean pressure readings, control cause-and-effect, commissioning results and maintenance log together. When performance changes, comparison with this baseline is more useful than replacing parts by guesswork.
Project or service checks
- Request the design airflow, not only the ESP model number.
- Confirm the unit is suitable for the cooking duty and grease loading.
- Record the clean pressure drop and any alarm set points.
- Provide interlocking with the extract fan as required by the manufacturer.
- Allow a safe route to withdraw full-size collector cells.
- Agree who cleans the cells and where contaminated wash water is handled.
- Include electrical and functional checks in commissioning.
Turn the agreed checks into named deliverables. Each item should have an owner, due date and acceptance method. Where a measurement is required, record the value, unit, instrument or source, operating condition and result. This makes the information usable at handover and during a later investigation.
Common mistakes to avoid
- Calling an ESP an odour eliminator.
- Selecting a unit from maximum catalogue airflow without checking the real duty.
- Installing it where cells cannot be withdrawn.
- Allowing air to bypass around poorly sealed cells or access doors.
- Adding the ESP without checking fan selection and system resistance.
Avoid closing the issue on appearance alone. A new filter, reset controller or revised drawing may change the symptom without resolving the underlying duty, utility, access or maintenance problem. Confirm the completed work under a representative operating condition and keep the evidence with the asset or ventilation record.
Frequently asked questions
Does an ESP replace carbon filtration?
No. They treat different pollutant forms. An ESP mainly controls particles; carbon is normally used for suitable gaseous compounds after effective pre-filtration.
Can staff clean ESP cells?
Only if the manufacturer, risk assessment and site procedure allow it and the cells have been safely isolated and removed. Live internal diagnosis belongs to a competent service engineer.
Does every kitchen need an ESP?
No. The required treatment depends on cooking duty, site risk, discharge, planning requirements and the performance needed from the complete system.
Related Kitchen Install Guide reading
- Commercial Kitchen Odour-Control Systems Guide
- What Is an EMAQ+ Kitchen Odour Assessment?
- What Is DW/172?
Plan the whole commercial kitchen, not one isolated component
Use the Commercial Kitchen Install Guide to coordinate extraction, equipment, utilities, drainage, safety, access and handover before work reaches site.
Sources and further guidance
- BESA: DW/172 Specification for Kitchen Ventilation Systems
- HSE: Ventilation of kitchens and catering establishments
- Purified Air: Commercial kitchen ESP systems
- Extechnology: ESP, carbon, ozone and kitchen extract treatment
Last reviewed: 14 August 2026. This article provides general commercial-kitchen design information. It does not replace a site-specific ventilation design, manufacturer instructions, risk assessment, planning conditions or advice from a competent specialist.