Why this screen
Small plants, a bypass around a mechanical screen, or a first cut so a storm does not bury the climber. Cheap, no power, no controls.
Simulations
How the machines work
Animated drawings of the units in a treatment plant. Tap a part to read what it does. Change a number and watch the water, sludge, or air move. Same operator-sheet math as the Tools — US gallons, dual units.
Hand-cleaned Bar Rack
The oldest headworks screen: a coarse rack of steel bars, a couple of inches apart, set so an operator can rake it from the deck. It catches rags, sticks, and the occasional 2×4. Sand still goes through, and so do modern wet wipes.
Advantages
Simple. No motor to trip. A spare rake and a deck are the whole machine. Headloss stays low because the openings are huge.
Disadvantages
Labor. In a storm the rack blinds in minutes if nobody is standing there. Anything under about 2 in rides through to grit and primary. OSHA hates the confined-space raking.
This page is a demonstration — no flow math, no unit conversions. Watch rags hang on the bars and grit pass through. Opening and rake motion change with the screen type.
Hand-cleaned bar rack · elevation
2 in clear · 45° · approach 2.0 ft/s (1.25–3)
Bars at 45° in an open channel. An operator rakes the mat up onto the deck. Tap a part.
Plant TimeH00M00S00
Results are theoretical operator-sheet values for plant checks and certification math. Short-circuiting, density currents, and instrument calibration will move field numbers. Confirm with your O&M manual, NPDES permit, and laboratory method before changing process setpoints.