A filter bank is two or more irrigation filters connected in parallel or series to clean water before it reaches driplines, emitters, laterals, sprinklers, or fertilizer injection equipment. A farm needs multiple filters when a single unit cannot safely handle the required flow, backup duty, or water-source contamination; a common rule is to add capacity before pressure loss or clogging becomes frequent.
What is a filter bank in irrigation?
In irrigation, a filter bank is a grouped filtration unit rather than one isolated strainer. It may use disc filters, screen filters, sand media filters, hydrocyclone separators, or combinations of these. The bank can share manifold piping, valves, pressure gauges, and sometimes automatic backwash controls.
The key rule is that a filter bank is sized by the whole system, not by pipe size alone. Designers should check maximum pump flow, emitter opening, water quality, allowable head loss, cleaning method, and whether irrigation must continue while one filter is being serviced.
Parallel filter banks divide flow between vessels. This setup is common for high-flow pump stations and large center pivots, drip blocks, or greenhouse projects. Series filtration treats water in stages: a coarse separator or screen removes heavy solids first, then a finer disc or media filter protects small emitters.
For example, HJLYGL supplies manual, semi-automatic, and fully automatic backwash disc filters, Y-type and T-type screen filters from 1.2 to 3 inches, high-flow sand media filters, and the HJLX-3 hydrocyclone sand separator. These units can be selected individually or grouped into a filtration train.
How does a filter bank work?
Water enters through an inlet manifold and passes through filter elements. Each element traps particles according to its filtration degree, also called mesh, fineness, or micron rating. Clean water then collects in an outlet manifold and moves toward the control valves and field laterals.
Pressure differential is the practical signal that a filter element is loading. As particles collect, the pressure difference between the inlet and outlet rises. Manual units require valve operation or element removal; semi-automatic and automatic backwash systems use reverse flow to flush trapped solids.
- Pre-separation: A hydrocyclone separator or coarse strainer removes sand, silt, and heavy grit before water reaches finer filtration.
- Primary filtration: Disc rings, screen mesh, or sand media capture remaining suspended particles.
- Pressure monitoring: Gauges or sensors compare upstream and downstream pressure.
- Cleaning: The operator or controller flushes the filter when differential pressure reaches the selected setpoint.
- Continuous supply: In a parallel bank, other filters can keep running while one vessel is backwashed or serviced.
Disc filters use grooved rings that provide both surface and depth filtration. HJLYGL disc filtration grades span approximately 40 to 300 mesh, from about 400 micron down to 50 micron. Some units use a centrifugal inlet design that keeps larger particles away from disc stacks, which can lower head loss during operation.
When does a farm need multiple filters instead of one?
A farm usually needs multiple filters when one filter cannot meet flow demand, cannot provide the required protection level, or would force irrigation to stop during cleaning. Multiple units are especially useful where river water, pond water, well water with sand, recycled water, or algae loads change through the season.
Use multiple filters when design flow exceeds the clean, safe operating range of one selected housing. It is better to have a modest safety margin than to run a single filter continuously at its upper flow limit, particularly with dirty water.
- High-flow fields: Large drip parcels, pivot systems, nurseries, and irrigation pump stations often exceed the capacity of one small disc or screen filter.
- Dirty surface water: Ponds, canals, and rivers may carry algae, organic debris, silt, and aquatic life, requiring staged filtration.
- Sandy borehole water: A hydrocyclone separator before a disc or screen filter can reduce abrasive load.
- Small emitters: Drip tape and pressure-compensating driplines have small passages and need consistent filtration fineness.
- Continuous operation: Parallel filters allow backwashing or maintenance without shutting down the whole irrigation shift.
- Fertilizer injection: Filtration after or around injection points helps catch undissolved fertilizer particles before they enter laterals.
A single filter may be enough for a small well-watered block with steady flow, low sediment load, and a compatible emitter size. Multiple filtration becomes more attractive when water quality varies or downtime is costly.
Which filter arrangement is better: parallel or series?
Parallel and series arrangements solve different problems. Parallel filters mainly increase flow capacity and provide backup. Series filters mainly improve particle removal by separating coarse and fine jobs. Many commercial farms use both ideas in one system: a separator first, then a parallel bank of finer filters.
Choose parallel for capacity; choose series for treatment stages.
| Arrangement | Main purpose | Typical farm situation | Common components | Maintenance note |
|---|---|---|---|---|
| Single filter | Basic protection for lower flow | Small plot, clean well water, modest irrigation schedule | Disc filter or screen filter | System may need to stop during cleaning |
| Parallel filter bank | Higher total flow and redundancy | Large drip block, pivot, greenhouse manifold, continuous irrigation | Two or more disc, screen, or media vessels on manifolds | One unit can often be isolated while others remain online |
| Series filtration | Step-by-step solids removal | River, pond, canal, sandy well, or recycled water | Hydrocyclone or coarse strainer followed by disc, screen, or media filter | Coarse stage protects the finer stage and can reduce cleaning frequency |
| Hybrid filter bank | Capacity plus staged cleaning | High-flow project with variable water quality | Separator, parallel disc or media filters, valves and gauges | Requires clearer manifold layout and operator training |
For T-type manual disc filter units, HJLYGL examples include the HJLYGLT002-1M2D at 2 inch/DN50 and the HJLYGLT003-1M3D at 3 inch/DN80. Their listed filtration area is 198 to 699 cm², maximum flow is 26 to 56 m³/h, maximum working pressure is 10 bar/145 psi, and maximum water temperature is 60°C. Available grades include 80 mesh at about 180 micron, 120 mesh at about 125 micron, and 150 mesh at about 100 micron.
How do you choose mesh, micron rating, and filter count?
Start with the emitter or nozzle requirement, then consider water quality and flow. The mesh number describes screen or disc fineness; higher mesh generally means smaller openings. Approximate equivalents include 40 mesh at 400 micron, 80 mesh at 180 micron, 120 mesh at 125 micron, 150 mesh at 100 micron, 200 mesh at 75 micron, and 300 mesh at 50 micron.
Do not select the finest mesh automatically; finer filtration can increase cleaning frequency and head loss when source water is dirty.
- Identify the smallest passage in the drip tape, emitter, dripline, nozzle, or injector.
- Check the emitter manufacturer's required filtration degree.
- Test or observe the water source for sand, silt, algae, organic matter, and fertilizer residues.
- Select a coarse pre-filter where heavy solids are present.
- Choose the disc or screen mesh that protects the emitter without causing excessive pressure loss.
- Add filter vessels until total available flow covers the pump and field design flow with margin.
- Include pressure gauges, sample ports, drain valves, and enough clearance for element removal or backwash piping.
Screen filters often work well for relatively manageable inorganic particles, while disc filters are a common choice because the grooved rings handle mixed particles and can be cleaned by flushing. Sand media filters are often used for high-flow or organic-load surface-water conditions. A hydrocyclone is a pre-treatment device, not a replacement for the final emitter protection filter.
What maintenance and project details should buyers confirm?
A well-built filter bank needs more than filter housings. Buyers should confirm connection type, manifold velocity, drain discharge, pressure rating, spare seals, cleaning access, and whether automation is needed. HJLYGL offers male thread, clamp, and flange connections on listed T-type disc units, and supports OEM/ODM items including logo, packaging, port sizes from 1 to 4 inches, and filtration degrees.
Every filter bank should be easy to isolate, inspect, flush, and return to service.
For procurement planning, common HJLYGL models are typically in stock, with a typical lead time of around 7 to 15 days, sample orders supported, and long-term spare parts supply. The stated warranty can be up to 10 years under normal use; buyers should confirm the exact terms for the selected model and operating conditions.
FAQ
Is a filter bank the same as one large filter?
No. A filter bank uses two or more filter units connected together, usually to increase flow capacity, provide staged filtration, or allow cleaning while irrigation continues.
What is the difference between parallel filters and series filters?
Parallel filters share total flow and add capacity. Series filters treat the same water in stages, with a coarse filter before a finer filter.
How many filters does a drip irrigation system need?
A small, clean-water system may need only one quality disc or screen filter. A large drip block, dirty water source, or continuous-operation system may need a separator plus two or more parallel filters.
What mesh is best for drip tape?
There is no single universal mesh. Follow the drip tape or emitter requirement; 120 mesh at about 125 micron and 150 mesh at about 100 micron are common finer protection levels, while 80 mesh at about 180 micron may be suitable where specified.
Can a hydrocyclone sand separator replace a disc filter?
No. A hydrocyclone removes heavy grit and sand using centrifugal action, but a disc, screen, or media filter is still needed to protect emitters from finer remaining particles.
When is automatic backwashing worth specifying?
Automatic backwash works better when labor is limited, irrigation runs almost continuously, or source water loads filters frequently. Manual units can be practical where operators are present and cleaning intervals are manageable.
Does adding more filters reduce pressure loss?
Parallel filters can reduce velocity and pressure loss across the bank when correctly sized, but undersized manifolds, blocked elements, or poor valve layout can still cause loss.
What information should be sent to a filtration supplier?
Send pump flow in m³/h or gpm, pipe size, water source, particle type, emitter requirement, working pressure, available footprint, cleaning preference, and whether fertilizer injection is used.
Size a filter bank from the emitter backward and the water source forward, so every stage has enough capacity, the correct fineness, and a practical way to be cleaned.