MGF — Multi Grade Filter

Multi-Grade Filtration — Reliable Suspended Solids Removal

A Multi-Grade Filter (MGF) contains multiple layers of quartz sand and gravel graded from coarse to fine. Water flows downward through the media, with progressively finer layers trapping particles of decreasing size — from >100 µm in the gravel layer down to 20 µm in the fine sand. Outlet turbidity is consistently below 1 NTU from feed turbidities up to 50 NTU.

MGF is the most common and cost-effective first-stage treatment in any water treatment train. It protects downstream activated carbon filters, softeners and RO membranes from suspended solids loading, dramatically extending their service life. Our MGF vessels are supplied in FRP (fibre-reinforced plastic) or MS epoxy-lined with manual or automatic multi-port valve (MPV) backwash.

Layers of 12–25mm gravel, 3–6mm gravel, 1–2mm coarse sand, 0.5–1mm medium sand, 0.3–0.5mm fine sand. Graded layer structure maximises TSS removal and backwash efficiency.

Upflow high-velocity backwash (8–12 m/h) restores filter bed every 24–48 hours. Multi-port valve or individual valve manifold. Auto timer or differential pressure triggered.

FRP vessels for standard applications (max 10 kg/cm²). MS epoxy-lined for high-pressure/high-temperature. Sizes from 8 inch to 84 inch diameter.

Top-mounted 6-way MPV allows filter, backwash, rinse, drain — single valve operation. Manual or electric actuator. 1½ inch to 4 inch connection.

DP gauge/transmitter monitors filter head loss. Auto backwash trigger at ΔP >0.5 bar. Prevents breakthrough and extends media life.

Quartz media replacement every 5–7 years or after 50,000+ backwash cycles. Media grading certificate supplied. Field media replacement service available.