The steel gravity valveless filter is a fully automated filtration system developed by our company, operating on the principle of hydraulic siphon. Featuring a steel tank structure and eliminating the complex valve control systems of traditional filters, this innovative design utilizes hydraulic technology to automatically complete the entire filtration cycle—comprising filtration, backwashing, sludge discharge, and re-filtration. It provides an efficient solution for removing suspended solids and turbidity in water, with user-friendly operation and relatively low energy consumption.
- Structure and Working Principle
- Core structural composition
The equipment features a steel-structured filter tank with its core system integrated inside.
- The filter tank: The main structure is made of carbon steel and treated with heavy-duty corrosion-resistant measures (such as rubber lining and epoxy coating), capable of withstanding operating water pressure and external environmental conditions.
- The filter medium layer: the core functional layer, typically filled with granular filter media such as quartz sand and anthracite, forming a deep filtration bed.
- Hydraulic automation system (critical):
- Siphon riser and auxiliary pipe: the "sensor" for monitoring the resistance of the filter layer.
- Siphon downpipe, breaker and forceer: the core parts of forming and destroying siphon and controlling backwash process.
- Water distribution and collection system: The top inlet distribution device and bottom collection device ensure uniform water flow.
- Working Principle
The device operates entirely through hydraulic automatic control, requiring no external commands:
- The filtration process: Raw water is evenly distributed over the filter media surface by the distribution device. Under gravity, it flows downward through the filter layer, where impurities are retained. The clean water is collected by the bottom water collection system and discharged through the "outlet pipe" utilizing the siphon principle.
- Backwash trigger: As impurities accumulate in the filter layer, the resistance increases, leading to greater head loss. This causes the water level in the siphon riser to rise progressively. When the water level reaches the auxiliary pipe opening, the water flows into the auxiliary pipe, triggering the siphon effect.
- Automatic backwashing: The strong siphon effect causes the clear water in the tank to flow upward at high speed to backwash the filter media, while the contaminants are carried away through the siphon downpipe. The backwash water is directly drawn from the clear water tank (i.e., the water stored in the filter tank itself) and continuous feed water.
- Cycle Recovery: When the water level in the tank drops to the point where the 'breakage hopper' is exposed, air enters the siphon pipe, automatically breaking the siphon. The backwash stops, and the equipment immediately resumes filtration mode to begin the next cycle.
- Core technical features
- The entire process is fully automated without external electrical control. From filtration and backwashing initiation to sludge discharge and system recovery, all operations are completed through hydraulic linkage. No external power supply, PLC, or dedicated personnel are required for valve operation, achieving high automation. This makes it particularly suitable for scenarios with limited power access or where unattended operation is required.
- The structure is simplified and the operation is reliable. The complex multi-way valve group, the electric control cabinet and the backwash pump are eliminated, so the mechanical failure points are less, the long-term operation reliability is relatively high and the maintenance workload is less.
- Low energy consumption: The backwash is powered by water's gravity and siphon effect, eliminating the need for additional backwash pumps. Over time, this system may consume less energy than filters requiring pump-assisted backwashing.
- Steel tank body with excellent strength and adaptability: Compared to concrete structures, steel tank bodies can be prefabricated in factories, allowing for easier quality control, shorter on-site installation periods, and greater adaptability to different site conditions.
- Main Technical Parameters
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Parameter item
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Description / Reference Range
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per unit processing capacity
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The design accommodates a wide range of tank sizes (e.g., diameter Φ2000-Φ4000mm).
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design filtration velocity
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8 – 12 m/h (normal range)
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average effluent turbidity
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Under normal operating conditions, the design is generally controlled within ≤ 3–5 NTU.
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terminal head loss
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1.5 – 2.0 m (i.e., the water level that triggers the formation of a backwash siphon)
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backwash intensity
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14 – 16 L/s·m² (design assurance)
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filter layer
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Commonly used quartz sand and anthracite in double or multiple layers, with a total thickness typically ≥ 1000mm
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Tank material
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Carbon steel with rubber lining for corrosion protection, carbon steel with epoxy for corrosion protection, stainless steel optional
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working temperature
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Room temperature (specific temperature range limited by the material of the anti-corrosion lining)
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- Typical Application Fields
This device is ideal for applications requiring stable filtration while minimizing operational complexity.
- Industrial water supply system: Serving as a bypass filtration or supplementary water treatment unit for circulating cooling water systems in thermal power plants, chemical plants, steel mills, and similar facilities.
- Municipal and rural water supply: the core purification and filtration unit for small and medium-sized waterworks and self-supplied water sources of industrial and mining enterprises.
- Advanced Sewage Treatment and Reuse: In the reclaimed water treatment process, this filtration unit operates after biological treatment or coagulation sedimentation to further reduce suspended solids (SS) and turbidity.
- Landscape water systems: Purify circulating water for parks, residential community lakes, and swimming pools to maintain crystal-clear water quality.
- Raw water pretreatment: serves as a protective pre-filtration step for membrane systems (e.g., reverse osmosis) or ion exchange systems.
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