An irrigation filter is a device that removes sand, silt, algae and debris from water so it cannot clog drippers, micro-sprinklers, laterals or valves. It works by passing water through a screen, grooved discs, sand media or a centrifugal chamber. A common rule is to filter drip water to at least 120 mesh, about 125 microns.
What is an irrigation filter?
An irrigation filter is a water-treatment component installed between the water source and the irrigation network. It catches or separates particles that can block small flow passages. In a drip system, even a small amount of sand or algae can close an emitter, reduce uniformity and create dry spots in a field.
Buyers may use different words for the same equipment: irrigation strainer, filtration unit, filter housing, dripline filter and emitter protection filter. These terms overlap, but the job is the same: protect downstream equipment without causing excessive pressure loss.
Filters are used with well water, river water, pond water, reservoir water, recycled water and municipal or tank supplies. The correct unit depends on water quality, flow rate, emitter opening, pipe size and how often the operator can clean the system.
HJLYGL, also known as Lvze Hongsen / Henan Haojun Agricultural Technology Co., Ltd., makes manual, semi-automatic and fully automatic backwash disc filters, screen filters, sand media filters and hydrocyclone separators in Zhengzhou, China.
How does an irrigation filter work?
Most filters work by forcing water through a barrier with openings smaller than the particles that must be removed. As water moves through, clean water passes downstream while dirt is trapped on or inside the filter element. When dirt builds up, pressure loss rises and cleaning is required.
The key operating rule is: filtration degree must be smaller than the smallest protected flow passage, while filter area must be large enough for the required flow. A filter that is too fine may clog quickly. A filter that is too coarse may protect emitters poorly.
Pressure gauges installed before and after the filter show differential pressure. A rising pressure difference means the screen, disc stack or media bed is loading with sediment. Manual filters are brushed, flushed or opened for cleaning. Backwashing filters reverse flow or use hydraulic cleaning to discharge trapped debris.
Which type of irrigation filter is used for different water sources?
No single filter fits every water source. Sandy well water often needs a hydrocyclone separator before a screen or disc filter. Pond or canal water with organic matter may require a media filter, sometimes followed by a finer secondary filter.
| Filter type | How it removes particles | Typical use | Maintenance profile |
|---|---|---|---|
| Screen filter | Water passes through a perforated or woven screen | Clean well water, tank water, pump outlets | Manual screen washing or flushing |
| Disc filter | Water passes through compressed grooved rings that trap material on the surface and within grooves | Drip tape, orchards, greenhouses, mixed silt and organic particles | Manual, semi-automatic or automatic backwash |
| Sand media filter | Water travels through a bed of graded sand | Pond, river, reservoir and recycled water with algae or organic load | Backwash pump or valve operation |
| Hydrocyclone sand separator | Centrifugal force spins heavy sand outward and drops it into a collection chamber | Well water with high sand load | Flush sediment chamber regularly |
A common design choice is staged filtration: separate heavy sand first, then remove finer silt or organic matter before the driplines. This can reduce frequent clogging and lower the load on the final filtration unit.
For example, the HJLYGL HJLX-3 hydrocyclone sand separator is intended for sand separation, not as the only protection for drip emitters. It works better when followed by a screen or disc filter selected for the emitter size.
What do mesh, micron and filtration degree mean?
Mesh describes the number of openings per inch in a screen or the fineness rating used for disc rings. Micron describes the approximate particle size that can pass. Higher mesh generally means finer filtration and a smaller micron opening.
| Mesh grade | Approximate opening | Typical irrigation consideration |
|---|---|---|
| 40 mesh | Approximately 400 micron | Coarse prefiltration for larger particles |
| 80 mesh | Approximately 180 micron | Common for less sensitive systems or wider passages |
| 120 mesh | Approximately 125 micron | Common starting point for many drip systems |
| 150 mesh | Approximately 100 micron | Finer protection where emitter passages are small |
| 200 mesh | Approximately 75 micron | Fine filtration; check flow and cleaning frequency |
| 300 mesh | Approximately 50 micron | Very fine filtration for selected applications |
Use mesh and micron together when ordering, because suppliers may use either term. HJLYGL disc filtration covers approximately 40 mesh to 300 mesh, or about 400 micron down to 50 micron.
On HJLYGL T-type manual disc units, examples include 80 mesh green discs at about 180 micron, 120 mesh red discs at about 125 micron and 150 mesh orange discs at about 100 micron. Always confirm the emitter manufacturer's required filtration degree before purchase.
How do you select and size an irrigation filtration unit?
Selection should start with the water source and the most sensitive downstream emitter. Flow rate, connection size, working pressure, particle type, cleaning method and available labor all matter. A filter that works well on clean groundwater may be unsuitable for an open canal.
- Identify the water source and sample it for sand, silt, clay and organic matter.
- List the smallest emitter, micro-sprinkler or valve passage and its required filtration rating.
- Calculate system flow in m³/h or gpm and confirm pipe or DN size.
- Choose the filter principle: screen, disc, sand media or hydrocyclone separation.
- Select a filter body and element rated for the flow without excessive head loss.
- Choose manual, semi-automatic or fully automatic cleaning based on labor and dirt load.
- Add pressure gauges, isolation valves, flushing valves and bypass piping where required.
- Plan maintenance access and confirm spare discs, seals, screens and gaskets are available.
Do not size a filter by thread size alone; always verify maximum flow, filtration area and pressure rating. For reference, HJLYGL T-type manual disc filter models HJLYGLT002-1M2D and HJLYGLT003-1M3D cover 2 inch/DN50 and 3 inch/DN80 sizes, filtration area from 198 to 699 cm² and maximum flow from 26 to 56 m³/h. Their maximum working pressure is 10 bar, or 145 psi, and maximum water temperature is 60°C. Ports can include male thread, clamp or flange connections.
Why do filters clog and how are they cleaned?
Filters clog because they are holding material back. Sand loads the surface, silt can pack tightly, algae can form a mat, and fertilizer residue may add scale or sticky deposits. Clogging is not always a sign that the filter is too fine; it may show that water quality requires pre-treatment, larger filter area or more frequent backwashing.
- Screen strainers are usually flushed, brushed or opened for washing.
- Disc filters are cleaned by loosening or releasing the grooved rings so trapped particles can flush away.
- Sand media tanks are backwashed to expand the media bed and carry trapped dirt to drain.
- Hydrocyclone separators require periodic purging of collected sand from the sediment chamber.
Clean the filter when differential pressure rises or according to a scheduled inspection, not only when irrigation performance collapses. Automatic backwash filters work better when labor is limited, water is dirty or the system runs long daily irrigation cycles.
Frequently asked questions
What happens if an irrigation system has no filter?
Sand, silt, algae and debris can enter laterals and block emitters. This reduces flow, lowers water distribution uniformity and may cause crop stress in parts of the field.
Is a disc filter better than a screen filter?
A disc filter often works better when water contains mixed silt and small organic particles because grooved rings provide surface and depth filtration. A screen filter is a common choice for cleaner water and simpler maintenance.
What mesh is best for drip irrigation?
Many drip systems use 120 mesh, approximately 125 micron, as a starting point, but the correct rating depends on the emitter manufacturer's specification and water quality. Some small emitters require 150 mesh or finer.
Can a hydrocyclone replace a drip filter?
Usually no. A hydrocyclone sand separator removes heavy sand using centrifugal force, but fine silt and organic matter may still pass through. It is commonly installed before a disc or screen filter.
What is the difference between mesh and micron?
Mesh refers to fineness based on openings per inch, while micron is a physical particle-size unit. For example, 120 mesh is approximately 125 micron and 200 mesh is approximately 75 micron.
How often should an irrigation filter be cleaned?
Clean it when the pressure difference across the filter rises, when flow drops, or on a schedule set by water quality. Sandy or algae-rich water may require daily or weekly attention; clean water may require less frequent service.
What pressure can an HJLYGL disc filter handle?
The listed T-type manual disc filter units have a maximum working pressure of 10 bar, or 145 psi, and a maximum water temperature of 60°C. Verify the exact model datasheet before installation.
Where is an irrigation filter installed?
It is normally installed after the pump and control valves but before the irrigation laterals and emitters. When fertilizer injection is used, the filter is usually placed downstream of the injector to protect driplines from undissolved material.
Size filtration from the emitter backward: choose the required protection grade first, then provide enough flow area, pre-treatment and cleaning capacity to keep pressure loss stable over the irrigation season.