GB/T 40258-2021 in English
VALIDEvaluation method for corrosion resistance of hollow fiber membrane to chemical cleaning agent
- Issued on:2021-05-21
- Implemented on:2021-12-01
- File Format:PDF
- Delivery:Via email within 1~3 business days
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《GB/T 40258-2021中空纤维膜耐化学清洗剂腐蚀性能评价方法》由TC382（全国分离膜标准化技术委员会）归口，主管部门为国家标准化管理委员会。
Introduction
Analysis of the core content of the standard
GB/T40258-2021 specifies the corrosion resistance evaluation system of hollow fiber membrane to acidic (pH1.0), alkaline (pH13.0) and oxidizing (5000mg/L effective chlorine) cleaning agents. The standard innovatively adopts a multi-index weighted evaluation method to conduct a comprehensive classification based on the change rate of 6 key performance parameters.
Comparison of test methods
| Test items | Acidic conditions | Alkaline conditions | Oxidizing conditions |
|---|---|---|---|
| Immersion time | 24h(Oxidizing conditions need to be protected from light) | ||
| Key indicators | Breaking strength change rate ≤5% (Class I) | Breaking strength change rate ≤20% (Class I) | Breaking strength change rate ≤10% (Class I) |
| Tolerance level division | Grade 4 (Ⅰ-Ⅳ) | Level 4 (Ⅰ-Ⅳ) | Level 4 (Ⅰ-Ⅳ) |
Key points of technical implementation
Sample pretreatment specifications
The standard requires that samples must pass the air pressure integrity test of 0.05MPa (self-supporting membrane) or 0.02-0.03MPa (supported membrane), and the pH of the cleaning water after pretreatment must reach 6.5-7.5. Suggestions in practical application:
- Use GB/T6682 grade 3 water for rinsing
- The soaking time is strictly controlled within 4±0.5h
- The number of parallel test groups is not less than 5
Calculation of performance change rate
Take breaking tensile strength as an example, the calculation formula is:
ΔL=|LL0|/L0×100%
Where L0 is the average value of the blank sample, the test should ensure:
- Tensile speed (20±2)mm/min
- Ambient temperature (20±2)℃
- Grip length 100mm
Standard application suggestions
Membrane material selection guide
Recommended selection for different application scenarios:
- Municipal sewage treatment: at least Class III oxidation-resistant membrane
- Chemical wastewater treatment: Class I acid/alkaline resistant membrane required
- Food and pharmaceutical fields: Class I full-range qualified membrane is recommended
Challenging test design
When the cleaning agent concentration exceeds the standard:
- Perform gradient concentration test according to 4.6.4
- It is recommended to add FTIR surface group analysis
- Extend the immersion time to 72-168h
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