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Necessity of leak detection of high-efficiency filters
Necessity of leak detection of high-efficiency filters1. Many manufacturers use particle counter scanning methods to determine whether the design and installation of clean area air purification systems meet the requirements. Such verification is logically insufficient.Example: (1) After the purification test was passed in the newly built freeze-dried powder injection workshop of XXX Pharmaceutical Factory, the insoluble particles exceeded the standard in simulated production. After leak detection of high-efficiency filters using the PAO method, it was found that there were 30 high-efficiency filters in the 100-level area, 20 of which failed and 1 was replaced. (2) So far, no manufacturer in the 10,000-level area has passed the leak detection using the PAO method in one go. (3) High-efficiency filters in tunnel ovens rarely pass in one go. 2. In actual production, we often encounter more complex and worse situations than during testing. (1) Testing is static, while production is dynamic. The particles generated by the two are not of the same order of magnitude, and the requirements for filter capacity are also different. (2) When testing, the high-efficiency filter is newly installed, and the damage and leakage are basically within a relatively ideal range; after a certain stage of production, due to various reasons, some degree of damage, leakage, and blockage may occur locally. (2) Especially during the first test, the background environment is generally relatively ideal, and the air purification unit is started 1 to 2 hours in advance; during production, it may encounter different bad weather conditions and start 30 minutes in advance. It is not difficult to see that the data obtained during verification and monitoring is more ideal and in line with the requirements than the actual production at ordinary times. Therefore, given the characteristics and requirements of sterile preparations, the international community proposes a hundred-level protection under a hundred-level protection, and the domestic market promotes sterile ten-thousand-level and non-sterile ten-thousand-level protection. The purpose of both is to ensure the controllability of the sterility of the product and the insoluble particles. Still, the premise is that reliable hardware guarantees that the air purification system that meets the requirements is one of them. Therefore, the verification of the air purification system for sterile preparations should be more complete and reasonable than that of other dosage forms, and should not only stop at the qualified detection of particle count and microbial count. Analysis of the causes of high-efficiency filter leakage 1. The installer's sense of responsibility is not strong, resulting in improper installation. 2. The high-efficiency filter itself leaks and leaves the factory with defects. A. Lax inspection B. Poor quality of filter material C. Improper transportation D. The connection between the filter material and the frame is not tight. 3. Reasons for the quality of the static pressure box The static pressure box is a necessary accessory for the air supply system to reduce dynamic pressure, increase static pressure, stabilize airflow, and reduce airflow vibration. It can make the air supply effect more ideal. The static pressure box is a device that allows airflow to pass through and effectively prevents or weakens the propagation of sound energy outward. A. Conventional static pressure box (1) The material is a 1.0 mm galvanized sheet. The material is too thin and it is not easy to bear force when connected with the high-efficiency filter and is easy to deform. (2) The static pressure box is connected to the static pressure box body by welding after the edge of the frame is pressed. Because welding can easily cause the frame to be distorted and uneven, it is easy to produce leaks. (3) When connecting the high-efficiency filter and the static pressure box, 4 pressing plates are required to press the 4 corners of the high-efficiency filter and the static pressure box respectively. The pressure of the pressing plate on the filter is uneven, so the connection is not sealed. B. New static pressure box (1) The material is 1.5mm hot-dip galvanized sheet. Since the material is thicker than the conventional static pressure box, it will not deform when connected to the high-efficiency filter. (2) The static pressure box and the pressure edge are punched and formed by a punch press at one time without welding points, and the sealing performance is good. (3) Since the static pressure box is equipped with a pressure ring, the pressure on all four sides of the high-efficiency filter is pressed by the pressure ring when connected, so the force is evenly applied and the connection is better sealed. (4) The pressure edge of the static pressure box has been structurally modified to increase the support strength, so it can be stressed without deformation when connected to the high-efficiency filter. |
