Air Strainer Test Methods Weight Calculating Method
Test dust source is large size, high concentration standard dust. The main components of dust through the strainer, the specified region dust, and then mixed with the specified amount of the fine carbon black and short fibers. Most countries require using the Arizona desert "road dust" (Arizona Road Dust), Chinese standard stipulates using Loess Plateau village dust, the Japanese standard stipulates using "barrier East Asian clay."of from Japan. The measured "quantity" is the dust weight.
Strainers installed in the standard test wind tunnel, the upwind end with a continuous dust emission. From time to time, measuring dust weight through the strainer or strainer dust volume, and to get the strainering efficiency calculated according to dust weight of the strainer in this stage. The final weight efficiency is every test phases efficiency according to the weighted average quantity of dust.
Weight calculating method test terminal conditions is: the agreed final resistance value, or the efficiency significantly declines. Here the so-called "convention" refers to the agreement between the client and tester, or tester requirements themselves. Clearly, the agreed terminal test conditions are different, the efficiency value of weight is different.
when the test is terminal, strainers accommodate test dust are known as the " dust holding capacity."
Weight calcluating method is used to measure the low efficiency strainers, those strainers are generally used for central air-conditioning system in the pre-strainering.
Weight calculating method tests are destructive tests, can not be used in everyday products factory performance test.
Relevant standards: the United States ANSI / ASHRAE 52.1-1992, the Europe EN779-1993, China GB12218-89.
Dust-spot method
Test-bed and test dust are the same as the weight calculating method. Dust "quantity" is the sampling points high active strainer paper marsdenia volume.
sampling before and after the strainer, the sampling head with high-performance strainer paper, obviously, the pollution level of sampling point high active strainer paper before and after strainer will be different. During the test, each pass a period of dust emission tests, measuring the sampling points high active strainer paper marsdenia volume before and after strainer under the non dust emission. by comparing the difference between strainer paper marsdenia volume, using the specified method to calculate so-called "filtration efficiency." The final color efficiency is testing all process and each stage efficiency value in accordance with the weighted average amount of dust.
The terminal test conditions are similar to weight calculating conditions; the agreed final resistance value, or efficiency significantly declines.
Colorimetric method is used to measure the higher efficiency general ventilation strainers, most of strainers of air-conditioner system, belonging to such strainers. Colorimetric method was the testing method prevailing abroad, this method was gradually replaced by counting method.
The strict colorimetric method is destructive testing.
Relevant standards: the United States ANSI / ASHRAE 52.1-1992, the European EN 779-1993.
Atmospheric dust counting method
Dust source is natural dust in the atmosphere, dust "quantity" is larger or equal to a particular size of all particles numbers. Measuring dust instruments are ordinary optical or laser airborne particle counter. Efficiency value is the new strainer initial efficiency.
Atmospheric dust counting method is used to measure general ventilation strainers. Its efficiency value only represents the new strainer's performance.
China's efficiency rating is based on atmospheric dust counting method.
Standard: China GB12218-89.
Counting Particle Efficiency
Test bench is the same with the weight calculating method and colorimetric method, high concentrations test dust used in dust emission is also the same. Dust "quantity" is a small diameter segment particles number. Dust Measurement instruments are laser particle counter.
During the experiment, before and after each dust emission tests, you should take count measurement and calculate the filtration efficiency of various sizes of particles. When you reach the condition of stopping test, you should stop test. Typical efficiency values of the strainer are within the specified size, the instantaneous efficiency of the various stages in accordance with the weighted average amount of dust.
European standards require that when counting and measuring, using specific, multi-dispersed phase droplets, such as using the blow of the DEHS with Laskin nozzle spray, or use Latex ball that is the same standard particles of the demarcate counters. The U.S. requires counting measurements to use bleaching powder.
Counting efficiency is no longer a single value, but a different size of the strainer along the efficiency curve. European tests showed that when the test resistance is 450Pa, 0.4 m part counting efficiency value is close to the traditional colorimetric efficiency value. American Standard provisions point at different grades strainers measuring different size range of efficiency value, its test final resistance is still "two times of initial resistance or even higher."
The complete counting efficiency test is a destructive test, can not be used for product daily inspection.
Counting method efficiency is replacing colorimetric method efficiency.
Standard: European Eurovent 4/9-1993, the United States ASHRAE 52.2-1999, Europe PREN 779
