To assess the filtration effectiveness of water filters, a comprehensive evaluation from three dimensions is required: water quality indicators testing, equipment operational status, and practical application feedback. The core is to verify the impurity removal capability through data comparison and condition observation. The specific methods are as follows:

I. Water Quality Index Testing (Core Criteria)

By means of professional testing or portable instruments, compare the water quality parameters at the inlet and outlet of the filter, directly quantifying the filtration effect.

Suspended Solids (SS) Content

Testing Method: Measure the SS value (unit: mg/L) of import and export water samples using a suspended solids tester (or weighing method). Industrial circulating water must have a filtered SS of ≤10mg/L (≤5mg/L for equipment with precision accessories).

Criteria: Filtration Efficiency = (Import SS - Export SS) / (Import SS × 100%), qualified filter efficiency should be ≥80% (≥95% for high-precision models).

Particle Count (Key Indicator)

Testing Method: Utilize a laser particle counter to tally the number of particles of different sizes (e.g., 5μm, 10μm, 20μm) in imported and exported water samples.

Criteria: The removal rate of the filtered target particle size should be ≥90% (e.g., for a filter with a nominal filtration accuracy of 20μm, particles larger than 20μm should be almost completely removed).

Turbidity

Testing Method: Measure the turbidity of incoming and outgoing water using a turbidity meter (unit: NTU). Civil water purification requires turbidity ≤ 1 NTU, while industrial recycled water requires turbidity ≤ 5 NTU.

Criteria: Turbidity removal rate ≥ 85%, and stable export turbidity meets standards.

Special Impurity Testing

If the filtration target includes iron filings, calcium and magnesium ions, organic matter, etc., targeted testing is required.

Iron Content: Total iron/iron in solution (soluble iron) measured by spectrophotometer for import/export; industrial water ≤ 0.3 mg/L.

Organic matter: Measure COD/TOC values (e.g., for pure water pretreatment, COD ≤ 10mg/L).

Hardness: Titration method for measuring calcium and magnesium ions (softening water filter requires hardness ≤ 50 mg/L).

Section II: Equipment Operation Monitoring

The operating parameters of water filters can indirectly reflect the filtration effectiveness. Pay close attention to the following details:

Pressure differential change

Normal Condition: Inlet and outlet pressure difference of new water filter ≤ 0.05 MPa; as impurities accumulate, the pressure difference gradually increases (requires cleaning or filter element replacement when reaching 0.1–0.15 MPa).

Abnormality Determination:

Long-term low differential pressure (＜0.02 MPa): may indicate a damaged filter screen, substandard filtration accuracy, or a short-circuited water flow (not passing through the filter screen).

Rapid Pressure Surge: The rapid clogging of the filter screen may be due to an excessively high concentration of impurities in the incoming water or an improperly small filter screen aperture selection.

Wastewater Treatment Effectiveness

Observe the wastewater discharged from the outfall: If the wastewater contains a large amount of visible impurities (silt, rust, flocculent matter), it indicates that the water filter's interception effect is good.

If the wastewater is clear, it may indicate a failed filter screen (particles were not trapped) or exceptionally good incoming water quality (no impurities to filter).

Filter Integrity Inspection

Post-maintenance, disassemble and inspect the water filter / filter element:

Visual Inspection: Filter mesh shows no damage or deformation, with a uniform layer of impurities adhering to the surface (indicating effective retention).

Test: After rinsing the filter with clean water, inspect for holes by shining a light through it (microscopic damage can be detected using the bubble method).

Section III: Feedback from Real-World Application Scenarios

The final effectiveness of the water filter needs to be verified in conjunction with the operating status of the downstream equipment/system.

Downstream equipment failure rate

If the clogging and wear issues of equipment such as pipelines, pumps, valves, heat exchangers, and nozzles are reduced after filtration (e.g., the heat exchange efficiency of the heat exchanger remains stable and no scaling or clogging occurs), it indicates that the filtration effect meets the standard.

If downstream equipment continues to experience frequent malfunctions (such as nozzle clogs, pump housing wear), it is necessary to recheck the accuracy of the filter water unit or the integrity of the filter mesh.

Water Quality Stability

Continuous Export Water Quality Monitoring: Large fluctuations in water quality (such as sudden high and low SS values) may indicate incomplete backwashing of filter systems, partial clogging of filter screens, or sudden changes in incoming water quality that do not match the treatment capacity.

Energy Consumption Changes

In industrial circulating water systems, poor filtration can lead to increased pipeline resistance and reduced heat exchanger efficiency, manifested as increased pump energy consumption and insufficient cooling system cooling capacity.

If the post-filter system energy consumption remains stable or decreases, it indicates that the impurity removal is effective and the system operation efficiency has improved.

Four: Common Misconceptions and Precautions

Relying solely on "visually clear" is not sufficient: Water clarity does not indicate the absence of minute particles (such as suspended particles below 5μm), which require instrumental testing.

Neglecting Changes in Inflow Water Quality: If the concentration of impurities in the inflow water suddenly increases, the filter may become overloaded, necessitating timely adjustment of the cleaning frequency or upgrading to a newer model.

Unscheduled calibration of testing equipment: Turbidity meters and particle counters require regular calibration to prevent distorted detection data.

The core logic for evaluating the water filter's filtration effectiveness is: "Data Quantification (comparison of import and export water quality) + Equipment Status Verification + Downstream System Feedback." The combination of these three elements is necessary for a comprehensive and accurate assessment, to avoid misjudgment based on a single dimension.