The instrument for measuring professional filters is a photometer.
Release time:
2024-11-27
The testing steps for professional filters need to be mastered step by step and applied. Today, we will analyze the specific process through nine steps, and I believe that after reading this, you will have more confidence in using the equipment.
1. The dust source used in the professional filter test is 0.3mm monodisperse DOP droplets, where the 'amount' refers to the turbidity level of the air containing DOP.
2. The measuring instrument is a photometer.
3. At the beginning of the test, the DOP liquid is heated into vapor, which condenses into tiny droplets in a specific environment. After removing droplets that are too large or too small, only particles around 0.3mm remain, and the misty DOP enters the air duct.
4. Next, the turbidity of the air samples before and after the filter can be measured, which allows us to determine the filter's efficiency in filtering 0.3mm dust.
5. The DOP method has a development history of over 50 years and was once a commonly used method for measuring the performance of filtration equipment internationally.
6. By changing the dust generation parameters, other sizes of DOP droplets can also be obtained. Twenty years ago, measurements of the 0.1mm DOP method for filters were conducted in Europe and the United States, and the measuring instrument was changed to a condensation nucleus laser particle counter.
7. People may be concerned that the dust used in the experiment will contaminate the filter, so manufacturers will use dust that customers believe does not contaminate the filter during testing. For example, semiconductor chip factories do not like sodium salts, oil mist, or DOP, and often require manufacturers to use solid particle dust that they consider safe; while pharmaceutical factories require direct measurement of dust from outdoor air for the filter.
8. It is important to sample before and after the filter separately. The presence of salt mist in the air sample causes the color of the hydrogen flame to turn blue and increases brightness, and the flame brightness is used to determine the concentration of salt mist in the air, thus determining the filter's efficiency in filtering salt mist.
9. According to national standards, the average diameter of salt mist particles is specified as 0.4mm, but the actual measured results of existing domestic devices are around 0.5mm.
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