Choosing an Air Purifier by HEPA Class and CADR
An air purifier protects electronics and cleanroom workstations from particles, solder fumes and aerosols. This guide explains HEPA filter classes H13 and H14 to EN 1822, sizing via CADR and air change rate, and how to dimension the unit for your room.
View air purifiersWhat do HEPA classes H13 and H14 mean?
HEPA filters (High Efficiency Particulate Air) are classified in EN 1822 by their retention efficiency. The decisive figure is the efficiency at the Most Penetrating Particle Size (MPPS), typically 0.1 to 0.3 µm. Class H13 retains at least 99.95 %, class H14 at least 99.995 % of these particles.
For electronics workstations with solder fumes, H13 is usually sufficient because smoke particles and aerosols are reliably captured. Cleanroom-adjacent work and the assembly of sensitive boards often require H14 to keep the particle concentration within ISO 14644 limits.
How do you size via CADR and air change rate?
The CADR value (Clean Air Delivery Rate) states how much clean air a unit delivers per hour, given in m³/h. To size it, multiply the room volume by the desired air change rate. Electronics workstations typically use 5 to 10 air changes per hour, cleanroom-adjacent zones considerably more.
For example: a room of 30 m² and 3 m height has a volume of 90 m³. At 8 air changes per hour you need a CADR of around 720 m³/h. Choose the unit with headroom, because real throughput drops as the filter loads and on the quiet night setting.
- Determine room volume: length x width x height in m³.
- Set the air change rate: 5‑10x for electronics, higher for cleanroom.
- Required CADR = volume x air change rate.
- Plan 20‑30 % headroom for filter loading and noise.
- For point extraction at the bench, add local solder fume extraction.
What matters in selection and operation?
Beyond filter class and CADR, pre-filters, noise level and maintenance decide the practical value. A multi-stage build of pre-filter, activated carbon and HEPA extends the life of the expensive HEPA element and additionally binds odours and solvent vapours from the soldering process.
- Clean or replace the pre-filter regularly, or throughput drops.
- Include an activated carbon stage for solder and solvent odours.
- Document filter changes and watch the loading indicator.
- Place the unit freely, do not block intake and outlet.
Frequently asked questions
Is H13 enough or do I need H14?
For solder fumes and general electronics assembly, H13 with 99.95 % efficiency is usually sufficient. H14 with 99.995 % makes sense when you must meet cleanroom-adjacent conditions or a defined ISO class.
How do I calculate the required CADR?
Multiply the room volume in m³ by the desired air change rate. For 90 m³ and 8 air changes per hour that gives around 720 m³/h. Plan 20‑30 % headroom for filter loading.
What is the difference between HEPA and ULPA?
HEPA reaches up to class H14 with 99.995 % efficiency. ULPA filters of classes U15 to U17 to EN 1822 achieve up to 99.999995 % and are used in high cleanrooms.
How often must the HEPA filter be changed?
Depending on load and operating hours, usually every 12 to 24 months. A pre-filter and a loading indicator extend the life and show the optimal change point.
Looking for the right air purifier?
We supply air purifiers with true HEPA filters H13 and H14 to EN 1822 - correctly sized for electronics and cleanroom workstations.
Tested HEPA filters
H13 and H14 classified to EN 1822.
Correctly sized
Dimensioned by CADR and air change rate.
Multi-stage filtration
Pre-filter, carbon and HEPA combined.
Expert advice
Our specialists help with the sizing.