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About high efficiency filter leakage

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1, high efficiency filter leakage purpose

High efficiency filterThe filtration efficiency of itself is generally detected by the manufacturer, and the filter filtering efficiency report order and certificate of filter filtering efficiency report will be passed. For pharmaceutical companies, high-efficiency filter leakage refers to the high-efficiency filter and its system installation on-site leakage, mainly to check small pinhles and other damage in the filter material, such as frame sealing, gasket seal, and filtering Driving seams on the instrument frame, etc. The purpose of leakage is to detect the high-efficiency filter and its sealing of the installation of the installation of the frame, and timely discover the defects in the high-efficiency filter itself and the defects in the installation, take the corresponding remedial measures to ensure the cleanliness of the region.

Picture 1

2, DOP / PAO leak detection principle

High efficiency filterLeakage typically uses the PAO generator to deliver dust upstream, using a photometer detection filter upper and downstream aerosol concentration to determine whether the filter has leaks. The purpose of dust is due to the low concentration of dust particles in the high-efficiency filter, only the particle counter is detected without dust, and it is difficult to find that there is a leak, and it is necessary to supplement the dust.

When the gas stream is pumped into the light scattering chamber, the particulate matter scattered light to the photomultiplier. In the photomultiplier, light is converted into an electrical signal, and the signal is analyzed by the microprocessor after amplification and digitization, thereby determining the strength of the scattered light. By comparing the signals generated with the reference substance, the mass concentration of the particulate matter in the gas can be directly measured, so the use is very wide.
3, detection method

Determine whether the high-efficiency filter itself and its installation have obvious leaks, the following must be tested in the field: the filter material of the filter; the filter material is connected to the inside of its frame; the filter frame of the filter frame and filtration Between the support frame; support the frame and the wall or ceiling.

The material of DOP leaks, the instrument is: dust source (PAO solvent), aerosol generator, aerosol photometer.

It uses air without the need to compress the gas as a power. Under 20 Pa, the gas flow rate is 50 ~ 2025F3 / min, a multisperentispected submicron-free dust aerosol can be generated from 10 to 100 ug / ml. The aerosol photometer used is an ATI 2H type photometer, and the dynamic measurement range is from 0.00005 to 120 ug / L, the sampling flow rate is 1F3 / min (28.3 L / min).

The PAO aerosol was introduced on the top of HEPA to be tested. For HEPAs in the HVAC system, in order to make the aerosol to the HEPA constant concentration, the aerosol can be introduced directly from the negative pressure side of the system fan. If it is introduced from the wind tube, it should be at least 10 times from HEPA. The tube is introduced at diameter and minimizes the corner (US Environmental Sciences and Technology Society). In general, maintaining the upper aerosol reaches the required concentration, and the concentration fluctuations are within a certain range. For the lamination, HEPA on the ultimate stage, the aerosol is introduced directly from the negative pressure side of the system fan. The aerosol photometer is initialized, set 100%, 0% reference standard value, in accordance with aerosol photometric operation requirements, set alarm value. Connect the UPSTREAM sampling tube to the upstream sampling port, measuring the concentration of the upstream aerosol. The aerosol concentration of the occurrence of an aerosol gene occurred in accordance with the aerosol generator operation, so that the upper aerosol concentration reached 10 to 20 ug / ml.
4, scan detection

Removing the HEPA scatter board, between the entire filter surface, the filter and the border, between the border and the border, and the seal between the border and the static pressure box. The sampling headrobe filter surface is about 1 inches (about 2.54 cm) during the scan, and the scanning speed does not exceed 5 cm / s. Scanning is made back to the ground by straight line, and the line should be overlap. During the detection process, if there is alarm (ie the% Leakage (leak rate) exceeding 0.01%), it indicates that there is a leak. The leakage is used to scan inspection after using silica gel or fastening. Checking a filter for about 5 minutes. In the process of testing, the concentration of the upstream aerosol should be confirmed frequently, pay attention to the protective mask and protective eye mask during the test.
5, result judgment and processing

The high efficiency filter leak rate should be less than or equal to 0.01%. If HEPA is in the detection process, all points are not more than 0.01%, then the HEPA is qualified. If there is a% more than 0.01%, it is unqualified, and the point is marked. Need to fix or replace it. The high-efficiency filter filter leak allows for special glue, but the area of ​​a single leak is not greater than 1% of the total area, and the area of ​​all leaks cannot be greater than 5% of the total area, otherwise it must be replaced.
6, high efficiency filter leakage cycle
FDA recommends a leak detection every half a year in the production workshop of sterile preparation in the Sterile Pharmaceutical Production Workshop, and my country is recommended in the GMP inspection guide. ISO14644 has a leak detection of HEPA installed, and the suggestion is 24 months. DOP leaks should be made after HEPA installation or replacement. When the environmental monitoring shows that the air quality is deteriorated, or when the product is unqualified, the medium simulation filling test fails, it can be leaking as part of the deviation survey. A filter that requires leak detecting also includes HEPA used in drying tunnels and dry ovens.

7, problem discussion

(1) Efficiency and leakage of high efficiency filter

The high efficiency filter filtering efficiency refers to the efficiency of the filter itself, which varies depending on the standards and test methods. The current test method for efficient filter efficiency is: DOP method, with photometric detection, not as sensitive, the relevant standard can be seen in the US IEST-RP-CC001; particle counting method, the particle counter is used as the detection instrument, using single dispersion or Multi-dispersion aerosol, high sensitivity, mostly used for ultra-efficient filters, related standards can be seen in IEST-RP-CC007; 蕞 Easy to transmit particle size (MPPS) The law is that the EU EN1822 standard is stated that the difference from the particle counting method is that the particle size of the filter is easy to penetrate as the particle size of the test; the sodium flame method, this method uses flame photometer, the flame chromaticity of NaCl burning For response, the relevant standards see China \"high-efficiency air filter GB13554-92 \", the sensitivity is low, and NACL is unrequited abroad for microelectronic products.
For pharmaceutical companies, the high-efficiency filter leakage is mainly on-site leakage, and the problem may exist during the installation of the DOP method discovery. Also use aerosol photometers and multi-dispelling gas sol, due to its alignment aerosol, and can meet the requirements.
(2) aerosol photometer and particle counter

The detection instrument can use an aerosol photometer or particle counter. The particle counter detects the number distribution of the particles, often represented by \"granular / L \" unit, and the photometric is detected by the mass concentration of the particles, indicated by \"mg / L \". The particles of the multi-distribution particles and the large concentration distribution are not in the same particle size, since the particle size and weight are three times, the particle diameter particles occupy a large specific gravity in the concentration distribution. Therefore, when detecting the efficiency of the filter, the results obtained using the particle counter and the spectrometer will differ. The photometric sensitivity and precision are slightly poor compared to the particle counter, and therefore the high-efficiency filter and super efficient filter above the H13 class are not used. For the on-site leak detection of the pharmaceutical enterprise high-efficiency filter, the detection results are easy to judge, which is widely used for leak detection.

(3) Leak standard

Different criteria are also different from the determination of the leakage results. US IEST-RP-CC034 specifies that C, D-stage high-efficiency filter live leakage transmittance is 0.3 um, and the photometric scan detection can be 0.01. EU EN1822 specifies that leak detection is that the local transmittance of the filter does not exceed the prescribed local value, the H13 high-efficiency filter corresponds to 0.25%, but to note that the transmittance here is It is obtained by 0.3 um single-dispersed phase DOP test. my country in \"Clean Factory Design Code GB50073-2001 and High-efficiency Air Filters GB13554-92 \" on the leak test of the installed filter, specifically used atmospheric dust or other aerosol, using particle counter to measure leakage concentration, for efficient The filter, the penetration rate should not be larger than twice the filter factory qualified penetration rate. For the leak detection of the pharmaceutical enterprise HEPA, in the actual test, if there is a leak, the number of photosensitivity is significantly increased, and it is easy to judge.High efficiency filterLeak rate standards are set to be less than or equal to 0.01% does not affect the detection of actual leakage.


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