Product Information
A mechanical bar screen is the first line of physical defense at the inlet of wastewater plants and pumping stations. Its main job is to fish out floating debris, large chunks, and fibers so downstream pumps and pipes don't get clogged. The rake tooth mechanical screen is the most common type. It uses rows of parallel rake teeth linked into a continuous loop chain driven by a motor. As it runs, it automatically scoops up the debris trapped on the bars and dumps it into a conveyor or bin. As a key piece of wastewater treatment mechanical screening equipment, it usually comes with differential level control, starting and stopping based on the water level difference before and after the screen—keeping things running continuously while saving energy.
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Working Principle
Wastewater flows in through the channel and passes through the slowly moving rake teeth gaps, trapping suspended solids and large debris on the screen surface. A motor drives the sprocket at the bottom, moving the rake teeth in a circular upward path. As they climb, the teeth scoop up the trapped debris, carry it to the top, and drop it into a collection trough using gravity or a scraper. When the water level difference reaches the set point, the cleaning cycle kicks in automatically; when there's no debris, it goes on standby. No one needs to go down into the channel to operate it—solid-liquid separation is fully automated.
Application Fields
1.Municipal wastewater: intercepting plastics and fibers at pump station inlets.
2.Stormwater pumping: catching branches and trash during flood season to prevent impeller entanglement.
3.Industrial wastewater: pre-treating papermaking and dyeing inlets to separate large solids.
4.Water treatment plants: clearing weeds, fish, and floatables at intakes to protect pump sets.
FAQ
Q1: How do you choose the bar spacing for a rake tooth mechanical screen?
A: It mainly depends on what's downstream. If it feeds a submersible sewage pump, 10–20 mm is typical. If it's a coarse screen followed by a fine screen, 20–50 mm works for the coarse one. Tighter spacing catches more, but it increases water resistance and makes clogging more likely.
Q2: What if the mechanical screen keeps jamming?
A: It's usually big hard objects (like sticks or stones) or long fibers (like cloth strips or plastic ropes) getting caught between the rake teeth and bars. The equipment usually has overload protection (like a torque limiter or mechanical shear pin) that shuts it down or sets off an alarm when jammed. The fix is to stop the machine and clear the debris by hand. It's also a good idea to install a grit chamber upstream or add a catch net at the inlet.
Q3: What if the screen freezes in winter?
A: In cold regions, screens can freeze up on the rake teeth and chains, causing jams. You can add heat tracing or use hot water for flushing. A more common approach is to install the equipment indoors or add an insulation cover, and make sure it runs regularly during winter so it doesn't freeze from sitting idle.