Filter Element Precision Testing: An Authoritative Guide from Principle to Application

Abstract

This article systematically explains the testing methods and technical standards for filter element precision, and combines the testing practices of authoritative institutions at home and abroad to comprehensively analyze the principles, application scenarios and advantages and disadvantages of 10 mainstream testing technologies. By integrating the latest research results of professional testing institutions such as Beijing Qingxi Technology Research Institute and China Institute of Chemical Research, and combining industry standards such as ISO and GB, a complete filter element quality evaluation system is constructed. The article specifically introduces innovative equipment data such as LWL-16 online detector, and reveals the accuracy differences of different testing methods through comparison tables, providing a scientific decision-making basis for filter element manufacturers and end users.

1. The core value of filter element precision testing

1. Cornerstone of quality control As the "heart" of the filtration system, the pore size accuracy of the filter element directly determines the filtration efficiency. Research by Beijing Qingxi Technology Research Institute shows that filter elements with an accuracy error of more than 3μm can increase the failure rate of hydraulic systems by 42%, and strict testing can extend the service life of the equipment by more than 60%.

2. Industry compliance guarantee According to the GB/T 18853-2002 hydraulic transmission filter standard, all industrial filter elements must pass CMA/CNAS certification testing. According to the 2025 test data of the China Institute of Chemical Industry, the bacterial retention rate of substandard filter elements in the medical field is only 63% of the nominal value.

2. In-depth analysis of mainstream detection technologies

2.1 Microstructure analysis method

1. SEM electron microscopy detection A 1000-fold magnified image of the filter surface is obtained by scanning electron microscopy (Figure 1), and the pore size distribution can be accurately calculated with digital image processing technology. Experimental data show that the measurement error of this method for melt-blown filter elements is <000000>le;0.5μm, but there is a 15% sampling deviation for folded filter elements.

2. Bubble point pressure test Based on the classic detection method of capillary principle, the calculation formula is: 
   P = D 4 <000000>gamma; cos θ/D ​
   Where <000000>gamma; is the surface tension of the liquid (pure water 72.8mN/m), and D is the equivalent pore size. This technology has a detection efficiency of 98% for PP cotton filter elements, but is significantly affected by the wettability of the filter material.

2.2 Dynamic performance test method

1. Multiple passability tests Using LWL-16 online detector, the <000000>beta; value (filtration ratio) is calculated by continuously monitoring the particle concentration upstream and downstream of the filter element. The test data of a certain model of hydraulic filter element shows (Table 1) that after 5 cycles, the <000000>beta;₅ value dropped from 200 to 135, revealing the change in the deep dirt holding capacity of the filter material.

1. Light scattering particle counting According to ISO 16889 standard, a laser particle counter is used to detect 0.3-10μm particles. Comparative experiments show that the detection sensitivity of this method for ultrafiltration membrane is 3 orders of magnitude higher than that of the weight method, and it is particularly suitable for medical sterilization filter element verification.

3. Special scenario detection plan

1. Biosafety verification The Pseudomonas aeruginosa challenge test (ASTM F838) is used, requiring each square centimeter of filter membrane to withstand a 10⁶CFU bacterial impact. The 0.22μm filter element that passed the test can reduce the product contamination rate to 0.01% in the actual application of pharmaceutical companies.

2. Extreme working condition simulation According to the GB/T 8243.5-2018 standard, the cold start test was carried out at a low temperature of -30℃. Data from a certain automobile filter element company showed that the failure return rate of products that passed the test in the cold region market was reduced by 72%.

4. Trends in innovation in testing technology

1. Integration of intelligent testing systems A new generation of testing equipment, such as the Saicheng electronic filter element integrity tester, integrates 6 modes such as bubble point test and diffusion flow test, and improves the detection efficiency by 40%, and can realize remote quality monitoring through the Internet of Things platform.

2. Multi-dimensional evaluation system Establish an evaluation model with 12 indicators (Figure 2), covering dimensions such as physical accuracy, chemical tolerance, and biosafety. The system successfully identified 31% of "qualified but high-risk" products in the water purifier filter element test.

5. Industry application practice

• Medical field: Use bacterial challenge + bubble point method for double verification to ensure that the infusion filter meets the pharmacopoeia requirements • Food industry: Pass FDA-certified 3μm precision detection to effectively intercept yeast contamination • Aerospace: Execute GJB 509A-2000 military standard detection, and the filter element can withstand extreme temperatures of -55℃~175℃

Yhteenveto

Filter element precision detection has developed from a single aperture measurement to a multi-dimensional quality assessment system covering physical properties, chemical stability, and biosafety. With the popularization of intelligent equipment such as LWL-16 online detector, the detection efficiency has increased by 50%, and the data accuracy has reached 0.1μm level. It is recommended that manufacturers conduct CNAS certification tests regularly, and end users refer to GB/T 18853-2002 standards to establish test files to jointly promote the high-quality development of the filtration industry.