Valveless Filter

1. General Introduction:
The "Steel Gravity Non-Valve Filter Tank" is manufactured by the factory, with non-toxic coating for anti-corrosion. Units with filtration capacities from 20M³/h to 175M³/h are transported to the site as a whole; units with filtration capacities from 200M³/h to 500M³/h and from 300M³/h to 750M³/h are pre-fabricated and welded into several parts at the factory, then transported to the site where factory personnel complete the welding. After re-application of anti-corrosion, smaller specifications in this filter tank series adopt a square shape with a flat top cover, while larger specifications use a circular shape with a dome cover. They offer good sanitary protection conditions, can be installed outdoors, and compared to reinforced concrete filter tanks, have a smaller self-weight and can use flexible asphalt sand foundations.
2. Process Introduction:
This filter tank series uses a low-resistance drainage system, employing forward, gravity filtration. Backwashing is performed using the water volume in the clean water zone under the action of siphon head. Therefore, unlike high-speed filters, medium-speed filters, mechanical filters, and ordinary rapid filters, there is no need to install backwash water pumps or backwash water towers. Inside the filter tank, a larger number of wash and clean water pipes are used, arranged at the centroid axis of their respective area shapes, ensuring uniform distribution of backwash water. The filtered water is collected by a polygonal collecting trough in the clean water zone, allowing strong adaptability to the levelness of the weir top after the filter tank is in place, thus enabling uniform water collection.
In the larger specifications of this filter series, compared to the national standard reinforced concrete gravity non-valve filter, a three-tank per group series has been added (i.e., when one filter tank is backwashing, the backwash water volume is supplied by the three filter tanks in the same group). The maximum control value for terminal head loss has also been increased from the national standard's 1.70 meters to two levels: 1.50 meters and 1.90 meters, providing convenient product options for the elevation layout design of water purification plants.
3. Process Characteristics Description:
During operation, the filter tank automatically performs filtration—initiating backwashing—terminating backwashing—resuming the next cycle of filtration. This automation is hydraulic and requires no personnel supervision. 

Note:
The steel gravity non-valve filter series products are widely used for surface water purification, groundwater iron and manganese removal, circulating water side-stream filtration, suspended solids removal from production wastewater, post-filtration of organic wastewater after biochemical treatment and secondary sedimentation, and indoor swimming pool water filtration. It is an ideal water treatment equipment.
Currently, our factory produces two major series of non-valve filters: one is the square CBL-Ⅱ type filter with filtration capacities from 20m³/h to 175m³/h; the other is the circular DLB-Ⅱ and DLB-Ⅲ type filters with filtration capacities from 20m³/h to 80m³/h and from 200m³/h to 750m³/h. Among these, units with filtration capacities of 20m³/h and 175m³/h are transported to the site as a whole, while units with filtration capacities from 200m³/h to 750m³/h are pre-fabricated into several parts by our factory, transported to the site for assembly, and after anti-corrosion treatment, delivered to the construction unit. After filling with filter media, they can be debugged and operated.

4. Design Parameters
1. Average filtration rate: 10 m/h 2. Average backwash intensity: 15 L/m²·s
3. Backwash duration: 5 minutes 4. Terminal head loss value: 1.50 m, 1.70 m, 1.90 m (three options available)
5. Backwash expansion height: 700 × 40% plus 100mm safety height
6. Filter media layer height: 700mm, support layer thickness 270mm
7. Inlet turbidity: not greater than 20 NTU (for surface water purification)
8. Outlet turbidity: not greater than 3 NTU (for surface water purification)

Specifications and parameters: This equipment handles water flow rates from 20m³/h to 900m³/h
20M³/h to 175M³/h

200M³/h to 750M³/h