Definition
The separation of particles from water or air through a porous medium; in humidification systems it is the mandatory pre-treatment layer to prevent nozzle clogging, biofilm growth and UV shadowing (typical 5–25 μm particle filter + 1 μm carbon polishing).
Detailed Explanation
Water filtration removes mechanical contaminants, sand, rust and clay particles from the water entering a humidifier. The standard 3-stage train: (1) Sediment filter — 25 μm cellulose or polypropylene, coarse particles; (2) Multimedia depth filter — 5 μm, fine particles; (3) Carbon filter — 1 μm activated carbon, chlorine + organics. Total pressure drop is 0.5–1.5 bar; replacement every 3–6 months. Filtration is mandatory upstream of RO (protects the membrane); for cleanrooms an additional 0.2 μm membrane filter is added after RO.
Why It Matters
Without filtration, an adiabatic humidifier faces three problems: (1) NOZZLE CLOGGING — nozzles with 0.15 mm orifices clog on particles above 25 μm; monthly nozzle replacement gets expensive. (2) BIOFILM — particle contaminants offer bacterial attachment surfaces, biofilm builds, Legionella risk rises. (3) UV SHADOWING — turbid water absorbs UV, dropping disinfection efficacy (99.9% → 50%). On a 200 kg/h system running 5,000 h/year, filtration capex is €800–1,500 + €600/year maintenance; in return, nozzle + UV-maintenance savings are €5,000–8,000/year.
Practical Example
A textile plant near Izmir port had high-sediment mains water (averaging 35 μm particles). With a single-stage 25 μm filter, 20% of nozzles clogged in 2 months. NKT proposed a 3-stage train (25 + 5 + 1 μm) + biannual multimedia regeneration. Over the next 18 months, zero clogs, RO membrane life extended 40%, and UV CFU results stayed at "0 CFU/L".
Engineering Note
Filter sizing rule: max particle size ≈ nozzle orifice / 10. Example: 0.30 mm nozzle → 30 μm max. For RO membranes the cap is 5 μm. When filter pressure drop ΔP rises above 1.0 bar, it is replacement time; PLC-monitored systems use a differential-pressure transmitter as standard. Carbon is especially critical for chlorine (Cl₂) — city-water chlorine oxidises RO membranes. Standard order: sediment → multimedia → carbon → RO → UV → tank → pump → nozzles.
NKT Application Link
For this application NKT – Nem Kontrol Teknolojileri supplies the Neptronic SKH high-pressure atomisation system and the Neptronic SKVF evaporative cooler. Unit-selection support is based on space conditions, humidification load and the feed-water analysis; technical service and spare parts are provided. Design and installation of water treatment, as well as engineering design, installation and commissioning, remain within the scope of the facility's designer, contractor and water-treatment specialist.
