Design Manual › Pre-treatment › Fine / drum screen
FREE ENGINEERING TOOL · PRE-TREATMENT
Fine Screen & Drum Screen
Set the flow, aperture and through-screen velocity — get the screen area, the clean and clogged
headloss (your clog-alarm threshold), and the channel or drum geometry. The step that protects membranes
and MBBR carriers downstream from rags and grit.
1Duty & screen
Fine screens (1–6 mm) follow coarse bar screens; drum screens rotate the mesh out of the channel. Size area by through-screen velocity (0.3–0.9 m/s).
Results — area & headloss
Screen area A
—m²
Clean Δh
—mm
Clogged Δh
—mm
| Item | Value | Basis |
|---|
2Geometry
Channel screen: height from area ÷ width. Drum screen: length from area ÷ (π·D·capture).
| Item | Value | Basis |
|---|
Screening envelope
| Item | Value | Basis |
|---|
Quote the screen instruments at factory price
A fine screen needs a level-differential transmitter across the mesh (clog alarm), a flowmeter, and the rake/brush drive signal — mappable to our catalogue and supplied at the manufacturer's ex-works price (margin from the export rebate only).
Request a quote for this duty ← Headworks Vortex →Response within 24 hours · Inputs stay in your browser — nothing is uploaded.
Sources & parameter basis
| [1] | METCALF & EDDY 5th ed. / WEF MOP-8 — fine screen aperture 1–6 mm, through-screen velocity 0.3–0.9 m/s, drum capture factor ≈ 0.6. |
| [2] | Headloss Δh = K·v²/(2g); clean K≈0.5, clogged K = clog factor (≈2.5 at ~50% blinding). The clogged value is the differential-alarm setpoint. |
Full derivation and worked example: Fine-Drum-Screen-Calculation-Sheet.md. Fine screening protects the biology and any downstream membrane — run it, then carry Q into the grit chamber.
How do I size a fine or drum screen area?
Screen area = flow / through-screen velocity. The calculator returns screen area from your design velocity for municipal WWTP headworks.
What headloss does a fine screen or drum screen have?
Headloss rises from clean to clogged as openings block. The calculator returns clean and clogged headloss from screen opening and debris loading.
How do I size drum-screen geometry and channel?
Drum diameter and submergence plus channel width set capacity. The calculator returns drum and channel geometry for tropical municipal headworks.
Questions about a duty, a specification, or transparent sourcing? Contact our application engineers →