Inlet quality as a design variable
| Stage | Typical Specification | Purpose |
|---|---|---|
| Pre-filtration | 50–100 µm | Protects downstream stages from coarse particulates |
| Fine filtration | 1 µm, with a downstream 0.45 µm stage | Protects the orifice bore at tenths-of-a-millimetre scale |
| Softening | target < 25 mg/l CaCO₃ | Prevents scale formation at valves and the orifice |
| Reverse osmosis | target TDS 20–100 mg/l | Reduces dissolved solids to a band, not to a minimum |
| Inlet pressure boost | per pump specification | Ensures suction conditions, avoids cavitation |
Guidance values for ultra-high-pressure applications. The pump manufacturer's water specification governs.
Assess water quality against the manufacturer's specification
For the high-pressure side, particulates, dissolved solids, and temperature all matter. OMAX recommends analysing the available inlet water for waterjet cutting systems and notes that the necessary conditioning depends on the actual water quality. A blanket requirement for reverse osmosis or softening is therefore not useful; what governs is the analysis result against the specific pump or system manufacturer's limits.
Filtration protects high-pressure components and orifices
Filter stages reduce particulate loading in the inlet. Depending on water chemistry, softening, reverse osmosis, deionisation, or temperature control may additionally be required. Specification should account not only for the as-new state but also for fluctuating water quality, filter changes, and ongoing monitoring during operation.
Process-water handling depends on the application
In waterjet cutting, water, abrasive, and material particles are typically captured in the cutting tank. Enclosed cleaning or deburring cells, by contrast, require a defined return or discharge path for water and dissolved contaminants. For mobile work, simply collecting the process water safely can already be a substantial part of the system and logistics concept.
Removed material determines further treatment
Coating residue, rust, concrete particles, metal chips, or other material enter the water depending on the process. This creates requirements for sedimentation, filtration, sludge dewatering, recirculation, or disposal. What treatment is permissible and economical depends on the actual contamination and local requirements.
Media and disposal data belong in the requirements spec
- Inlet-water analysis and available temperature
- Manufacturer requirements for filtration and conditioning
- Water demand and expected process-water volume
- Type and quantity of abrasive, sludge, or removed material
- Desired recirculation rate and required water quality in the loop
- Operational and regulatory requirements for collection and disposal
Loop management and the wastewater side
The process side produces a mixture of water, removed material, and, in abrasive cutting, garnet. Whether this mixture is recirculated or discharged is a layout and permitting question, not a subordinate detail. In coating-removal and repair work, the nature of the released layer additionally determines the disposal route and can trigger hazardous-materials requirements.
- Solids removalSedimentation, filter press, or settling basin; estimate flow rate and dry-solids load
- Recirculation rateSet the share of water returned and the treatment depth this requires
- Discharge conditionsDirect or indirect discharge; clarify local wastewater ordinance and permit status
- Contaminants from the processOld coatings, heavy metals, oils; plan sampling before project start
- Abrasive disposalVolume generated, interim storage, waste code, and cost per tonne
- Water balanceFresh-water demand, evaporation, discharge with solids, make-up water
Discharge of process water is not a residual technical detail. Requirements follow from water-resources and wastewater legislation and the applicable local wastewater ordinance — in Germany, the Wasserhaushaltsgesetz and Abwasserverordnung, with local variation. For repair work on old coatings, hazardous-materials requirements can additionally apply. This clarification belongs at the start of project planning, not at commissioning.
Frequently asked questions about the water side
Is reverse osmosis required on every system?
No. It is common at ultra-high pressure when inlet water exceeds the manufacturer's specification. With soft, low-particulate inlet water, a combination of fine filtration and softening is often sufficient. The decision should always rest on a current water analysis, not an experience value from a neighbouring site.
How much water does a cutting system actually consume?
A cutting head with a 0.30 mm orifice at 4,000 bar draws roughly 2.7 l/min, or about 0.16 m³ per operating hour. Over a double shift, that is roughly 2.6 m³. Fresh-water demand is higher, because reverse-osmosis units discharge a concentrate; depending on recovery rate, one to two times that figure should be assumed.
Can abrasive be reused?
Technically yes, economically only at high volumes. Recycling plants separate, wash, dry, and classify the garnet; grain shape degrades in the process, and fines must be removed. Above a certain utilisation level, this pays off against buying new material plus disposal. Below that level, operating effort dominates.
- DIN EN 1829-1:2021-04, Safety requirements for high-pressure water jet machines – https://www.dinmedia.de/de/norm/din-en-1829-1/321847498
- Flow International, Fundamentals of the Waterjet Pump – https://www.flowwaterjet.com/explore/basics-of-a-waterjet-pump