How to Test the Efficiency of Air Filtration Membranes
Issuing time:2023-12-01 14:21
The filtration efficiency test of air filter membranes usually uses various standardized methods and techniques, including particle counting method, gravimetric method, photometric method, scanning electron microscope (SEM) method, challenge aerosol method, etc. Here, the more widely used particle counting method is used Here is a brief introduction to the method, which is the method of measuring the particle removal efficiency of filter membranes.
1. Selection of test particles
To use the particle counting method, you must first select particles that are relevant to the application and representative in the air filtration process. Their size distribution, concentration, and correlation with the intended application must be considered. Commonly used particles include the following depending on the industry and environment. Several types:
● Standard test particles, polystyrene latex (PSL) particles, which have a wide size range, ranging from nanometers to micrometers, are often used to test air filtration efficiency because these particles have a clear size distribution and are especially used in some benchmark tests. and comparison purposes.
● Dust particles are common air pollutants, so they are usually used as the first test for air filter membrane efficiency. The types are also relatively complete, and different types of dust particles can be selected according to expected environmental conditions. For example, for HVAC (air conditioning system) filters, synthetic dust or Arizona Road Dust (ARD) can be used, and for some industrial applications, specific industrial dusts can be selected, etc.
● Pollen and biological particles. Air filter membranes selected for testing such particles are mainly used in environments where pollen or biological contaminants (such as bacteria or viruses) are present. The morphology and correlation of particles can be used to evaluate filter removal. efficiency of these particles.
● Specific contaminants. In some special industry environments, such as clean rooms or pharmaceutical facilities, it is necessary to select specific particles or aerosols related to the production process, because this can test the air for specific contaminants relevant to the application. Filtration efficiency of filter membrane.
2. Set up a test device. The main function of this type of device is to simulate the operating conditions of the air filter membrane. The maximum procedures of the device's environment, pressure drop, air flow, temperature, etc. are close to and equal to the test environmental conditions.
3. Generate a test aerosol, using an aerosol generator to turn the selected test particles into a controlled aerosol. The generation of the aerosol ensures that the test particles are evenly distributed and representative of the particles encountered in the filtered air, in a controlled manner. Dispersed particles enable accurate control and measurement of particle concentration, which is important for determining filtration efficiency by comparing particle concentration upstream and downstream of the air filtration membrane. In addition, its controllable and repeatable test conditions reduce variability. and ensure the reliability of test results.
4. Measurement, first measure the concentration of particles upstream of the filter membrane to determine the baseline particle concentration, and then guide the test aerosol particles through the air filter membrane under controlled conditions. During this process, the air flow rate and pressure drop of the filter membrane must be monitored and It is maintained within specified parameters and then the downstream particle concentration is measured. The results of the test indicate the effectiveness of the air filter membrane in removing particles from the airflow.
5. Repeat the test and calculation, repeat the test multiple times with different filter membrane samples to ensure consistency and reliability, calculate the average filtration efficiency based on the repeated test data, and also repeatedly compare the particle concentration upstream and downstream of the filter membrane, etc. The data at each stage will ultimately lead to more scientific and practical results.
The efficiency test of air filtration membranes is an important step in all tests. It provides a basis for process control of membrane production. It is crucial to ensure its performance, maintain air quality, comply with regulations, etc. With the support of these data, it can effectively Make application decisions, quality assurance, and effective control of air pollutants.