Water Filtration Glossary
Plain-language definitions for the terms used across our product specifications and technical data sheets.
Filtration basics
| Term | Definition |
|---|---|
| Micron (µm) | A unit of length equal to one-millionth of a metre, used to rate the smallest particle size a filter screen removes. |
| Mesh | A count of screen openings per linear inch. Mesh count and micron rating only correspond directly once wire diameter is fixed. |
| Filtration degree | The rated particle size a filter screen removes, expressed in microns or mesh. |
| TSS (Total Suspended Solids) | The concentration of undissolved particles carried in water, typically measured in mg/L. |
| Differential pressure (dP) | The difference between inlet and outlet pressure across a filter, used as the signal to trigger an automatic backwash cycle. |
| Screen | The stainless steel filtering element itself — a perforated support cylinder carrying a woven or slotted mesh. The screen is what the micron rating refers to, and what the backwash cleans. |
| Filtration area | The total screen surface available for filtering, quoted in cm². At the same micron rating and flow, a larger area means lower velocity through the openings, a lower clean pressure drop, and longer intervals between backwash cycles. |
| Solids loading | How much suspended solids the filter receives per unit of water. It drives backwash frequency far more than flow rate does — the same filter on the same duty will cycle several times more often after a rain event. |
| Turbidity (NTU) | A measure of how much suspended matter clouds water, in Nephelometric Turbidity Units. A useful source-water indicator, but it does not describe particle size distribution, which is what actually sets the filtration degree you need. |
| Sediment | Settleable inorganic particulate — sand, silt, mill scale, corrosion products. The bulk of what a screen filter removes from bore, river, and dam water. |
Self-cleaning technology
| Term | Definition |
|---|---|
| Backwash | The cleaning cycle that removes collected solids from a filter screen, either automatically or by manual reverse flow. |
| Suction scanning | The Filtaworx cleaning mechanism — suction nozzles traverse the screen surface during backwash, drawing off solids while the rest of the screen keeps filtering. |
| Flush valve | The valve that opens during a backwash cycle to discharge solids and flush water to drain. |
| Rinse cycle / flush cycle | The short period, typically seconds, during which the flush valve is open and solids are cleared from the screen. |
| Automatic self-cleaning screen filter | A filter that cleans its own screen in place, without operator intervention or flow interruption. Also called an automatic backwash filter. |
| Hydraulic drive | A backwash drive powered by the line water itself. No electrical supply is required at the filter, which suits remote intakes and irrigation headworks. Needs a minimum of 2 bar line pressure to complete a cycle. |
| Electric drive | A backwash drive powered by an electric gear motor, giving precise control of scanner speed and cycle timing. Used where line pressure is low — from 0.5 bar — or where the cycle has to integrate with plant control. |
| Suction nozzle | The open port on the scanner assembly that passes close to the screen surface and draws collected solids off it. Nozzle geometry and clearance set how much water each cycle uses. |
| Scanner assembly | The rotating and traversing manifold that carries the suction nozzles across the full screen surface during a backwash cycle. |
| Differential pressure switch (dP switch) | The device that senses pressure drop across the screen and signals the controller to start a backwash once it exceeds the set threshold — typically 0.5 bar above the clean value. |
| Controller | The unit that decides when to backwash — on differential pressure, on a fixed time interval, or on manual command — and sequences the flush valve and drive through the cycle. |
| Continuous filtration | Filtration that is not interrupted by cleaning. Only a small patch of screen is under suction at any moment, so downstream supply keeps flowing at full rate throughout the backwash cycle. |
| Flush water loss | The volume of filtered water discharged to drain per backwash cycle. With a 5–17 second cycle it is a fraction of a percent of throughput, and it is the figure to compare when assessing water cost. |
| Backflush | A synonym for backwash, common in irrigation. See Backwash. |
Hydraulics and sizing
| Term | Definition |
|---|---|
| Flow rate | The volume of water passing through a filter per unit time, typically expressed in m³/h. |
| Operating pressure | The line pressure a filter is rated to run at, expressed in bar. |
| Pressure drop | The pressure lost as water passes through a filter screen, driven by filtration degree, flow rate and screen open area. |
| PN rating | A pressure rating standard (e.g. PN10, PN16) that defines the maximum allowable pressure for a flanged connection at a given temperature. |
| DN (Diametre Nominal) | A European standard for nominal pipe size, used to specify filter inlet/outlet connection size (e.g. DN150). |
| Clean pressure drop | The pressure loss across a new or freshly backwashed screen. It is the baseline the differential pressure setpoint is measured from, and it rises as the screen gets finer. |
| Minimum operating pressure | The lowest line pressure at which the backwash cycle still clears the screen — 2 bar for hydraulically driven filters, 0.5 bar for electrically driven. Below it the filter keeps filtering but stops cleaning properly. |
| Maximum operating temperature | The highest sustained water temperature the filter is rated for — 65 °C across the range, set by the seal and coating materials rather than the body. |
| Full-flow filtration | Filtering the entire flow in the line. Used where every litre reaching downstream equipment has to be protected — membrane trains, spray nozzles, heat exchangers. |
| Side-stream filtration | Continuously filtering a portion of a circulating volume rather than all of it. The standard approach on cooling tower circuits, where solids are removed faster than they accumulate without treating the full flow. |
| Bypass | A parallel line with isolation valves that allows the filter to be taken out of service for maintenance without stopping supply. |
Materials and standards
| Term | Definition |
|---|---|
| SS304 | A general-purpose stainless steel grade used for filter housings and screens in standard water applications. |
| SS316 | A stainless steel grade with added molybdenum for improved corrosion resistance, used where chloride exposure or corrosive water is a factor. |
| ISO 9001 | An international standard for quality management systems, covering design, manufacturing and service processes. |
| HACCP | Hazard Analysis and Critical Control Points — a food safety management framework relevant to filtration equipment used in food and beverage processing. |
| AS/NZS pressure vessel requirements | The Australian and New Zealand requirements filter bodies are tested to. Quoted alongside ISO 9001 on our manufacturing pages; the applicable standard depends on the vessel size and duty. |
| CIP (clean-in-place) | Cleaning process equipment in situ with circulated chemical solution, standard practice in food, beverage, and dairy. Lower solids loading upstream means fewer CIP cycles and less chemical use. |
Connections and flanges
| Term | Definition |
|---|---|
| Flange | A bolted pipe connection. Filter inlet and outlet flanges have to match the standard and pressure class of the pipework they join, which is why the connection standard is specified alongside the DN size. |
| AS 2129 Table D / Table E | The Australian flange drilling standard. Table D is rated to 10 bar, Table E to 16 bar. The two are not interchangeable — the bolt circles differ. |
| ISO 7005 / DIN PN10, PN16 | The metric international flange standards, rated to 10 bar and 16 bar respectively. PN16 is the common default on export projects. |
| ANSI B16.5 Class 150 | The North American flange standard, rated to 20 bar at ambient temperature. Specified on projects built to US practice. |
| BSP (British Standard Pipe) | A parallel or tapered threaded connection used on smaller filters, rated to 16 bar. The default on Australian irrigation and light industrial installations. |
| NPT (National Pipe Taper) | The North American tapered thread standard, rated to 16 bar. Not compatible with BSP despite similar appearance. |
Water sources and duties
| Term | Definition |
|---|---|
| Raw water | Untreated water taken straight from its source — river, dam, bore, or channel — before any filtration or chemical treatment. |
| Bore water | Groundwater drawn from a bore. Typically carries fine sand and iron precipitate, and its quality shifts over the life of the bore. |
| Process water | Water used directly in production — as an ingredient, a carrier, or a wash medium. Its filtration requirement is set by the product it touches, not by the pipework. |
| Recycled water | Treated wastewater reused for irrigation, washdown, or cooling. Solids loading is variable and organic content is higher than in mains supply, so automatic cleaning matters more. |
| Pre-filtration | Filtration installed to protect equipment further downstream rather than to meet a final water quality target. The duty most Filtaworx filters perform. |
| Membrane pre-filtration | First- and second-stage protection ahead of an RO or UF train. Removing particulate before the membranes cuts fouling, extends element life, and reduces CIP frequency. |
| Fertigation | Delivering fertiliser through the irrigation system. It raises the risk of emitter blockage, which is why filtration sits downstream of injection. |
| Turndown / duty-standby | Arranging multiple filters in parallel so flow can be shared, or one unit held in reserve. Used where flow varies widely or where the process cannot tolerate any interruption. |