Test methods for air filtration equipment

I. Colourimetric method

1. During the test, after each period of the dust test, the sampling points before and after the filter are measured in a non-dusty state, and the "filtration efficiency" is obtained by comparing the difference in the amount of light through the filter paper, using the prescribed calculation method.

2. The colorimetric method is generally suitable for measuring filters with high efficiency.

3. The colorimetric method has been replaced by the particle counting method because of the troublesome test procedure.

4. Colorimetric method of relevant standards: ANSI/ASHRAE 52.1-1992, European CEN779.

II. Atmospheric dust counting method

1. This is a method by our Chinese standards.

2. The dust source for the test is the natural "atmospheric dust".

3. The atmospheric dust counting method applies to general ventilation filters, and its efficiency value can only represent the performance of a brand-new filter.

4. The atmospheric dust counting method is relatively crude and the relevant authorities are currently considering revising the standard.

5. The standard of test: GB12218-89.

III. Gravimetric method

1. This is a test method that originated in the United States and is used internationally, but nowadays it is also used in China.

2. The test dust source for this method is a large particle size, a high concentration of artificial dust, the main component is the dust after screening, the specified area, and then mixed with a certain amount of fine carbon black, short fiber, or carbon black.

3. When conducting the test, the filter is installed in a standard test wind tunnel with continuous dust generation at the upwind end, and then the weight of dust passing through the filter and the amount of dust collected is measured at regular intervals to obtain the filtration efficiency value at that stage.

4. The test is terminated when the agreed final resistance value is reached or when a significant drop in efficiency occurs.

5. At the end of the test, the total weight of the filter holding the test dust is called the "dust capacity".

6. The relevant standards for the test: ANSI/ASHRAE 52.1-1992, CEN779, GB12218-89.

IV. Counting method

1. This is a common test method in Europe.

2. The test bench is similar to the counting method and the colorimetric method we introduced before. The high concentration of artificial dust is also the same as the counting method and the colorimetric method; the test can be counted and measured after each section of the dust test to calculate the filtration efficiency of the filter for various particle sizes.

3. The artificial dust used in the test is usually a specific polydisperse phase droplet.

4. The counting efficiency is not a single value, but a filtration curve along different particle sizes.

5. The efficiency of the counting method is now gradually replacing the colorimetric method.

6. Standards tested: European Eurovent 4/9-1993, American Ashrae 52.2P-1996.