How does the air filter membrane pressure drop test work?
Issuing time:2023-12-19 10:43
The pressure drop test of the air filter membrane is mainly to evaluate the air flow resistance through the filter membrane. The test data provides data and reference for the filter performance and its impact on the energy consumption of the ventilation system. Its main principles can be summarized into the following three aspects :
1. Air flow resistance. The main function of the air filtration membrane is to capture and intercept particles while allowing air to pass. When air flows through the membrane, it will encounter resistance due to various factors, including the pore structure, thickness and surface characteristics of the membrane. , and the interaction between air molecules and the membrane surface and the obstruction caused by particulate matter will affect the overall air flow resistance. The difference in pressure before and after passing through the membrane is measured to obtain the pressure difference data.
2. Filtration membrane pore structure, porosity and packing density. The microstructure of the filtration membrane is the most important influence in determining pressure drop. The size, shape and distribution of pores affect flow dynamics. Smaller and more pores will increase Air flow resistance, leading to higher pressure drop values, on the contrary, larger pores or a more open structure can reduce pressure drop, but may reduce filtration efficiency; the porosity of the filter membrane, that is, the ratio of the volume of the pores to the total volume, It is also a factor that affects the size of the pressure drop. Higher porosity usually allows more air to pass through, and the relative pressure drop is lower; in addition, the packing density of the filter media also affects the pressure drop, and a denser packing arrangement will produce a higher pressure drop. Multiple contact points and resistance between the air flow and the membrane will also lead to an increase in pressure drop.
3. Particle accumulation. Over time, the particles captured by the filter membrane will accumulate on the surface of the filter membrane or in the pores. The accumulation of particles and impurities will gradually increase the pressure drop, and the accumulated particles will be partially or completely blocked. pores, reducing the effective pore area and obstructing airflow. This particle accumulation will also become larger in the case of higher filtration efficiency, large particle size distribution and large load filter.
What are the methods for testing air filter membrane pressure drop?
There are many methods to measure air filter membrane pressure drop, including laboratory testing and field measurement. Laboratory testing usually installs the filter membrane in a test device to simulate the field environment, and uses a filter placed under controlled air flow conditions. The pressure drop is measured by differential pressure sensors before and after the filter, while on-site measurement generally directly installs the measuring equipment in the on-site filter or ventilation system. The on-site test data can truly reflect the performance of the filtration and provide direct guidance for operation and subsequent improvements. basis; for some high-precision industries, it is necessary to analyze from a microscopic perspective and have an in-depth understanding of the pressure drop mechanism, such as scanning electron microscopy (SEM) or optical microscopy and other technologies to check the surface and pore structure of the filter membrane before and after filtration. This type of analysis Helps identify factors such as particle accumulation, pore clogging, or changes in membrane morphology that may lead to increased pressure drop.
Therefore, the main purpose of testing is to serve the application. What kind of procedures and equipment are used? A better way is to conduct it according to the application standards of different industries and the type of filter membrane being tested.