1, high efficiency filter count scanning method
European common, similar to the United States, followed by other countries. The current international mainstream high-efficiency filter test method. The main measuring instruments for high-flow laser particle counter or coagulation nuclear counter (cnc). A counter is used to scan the entire effluent surface of the high efficiency filter, and the counter gives the number and particle size of dust at each point. This method not only measures the average efficiency of the filter, but also compares the local efficiency of each point. Counting scans are the most stringent method of testing high efficiency filters, and replacing them with other traditional methods is a big trend.
2, high efficiency filter oil mist method
The dust source is an oil mist. The “quantity” is the turbidity of the oil mist air. Instrument for the turbidity meter. The turbidity difference of the gas sample was used to determine the filtration efficiency of the filter on the oil mist particles. Although the Chinese standard can be used oil mist method, but domestic manufacturers are more willing to use the same standard provisions of the other sodium flame method, only part of the production filter media manufacturers in the measurement of filter material is still using the oil mist method. Relevant standards: China gb6165-85, Germany din24184-1990.
3, high efficiency filter sodium flame method
The average diameter of salt mist particles is 0.4mm according to national standard, but the actual measurement result of domestic salt mist device is 0.5mm. Europe on the actual test salt mist particle diameter measurement results for the 0.65mm. With the popularity of scanning methods, Europe has no longer use sodium flame method. The relevant domestic departments are revising the original national standards. Relevant standards: British bs3928-1969, Europe eurovent 4/4, China gb6165-85.
4, high efficiency filter photometer scan
Dust source is generally more dispersed droplets, such as laskin nozzle dop smoke generated. The whole plane of the filter was scanned using a photometer. This scanning method can quickly and accurately find the filter leakage. Since the dust source is a polydisperse phase and the photometer is unable to determine the particle size of the dust, this scanning method gives “filtration efficiency” of little practical significance. Some manufacturers and users believe that, as long as the quality of filter paper and strict control of the filter efficiency has been determined, therefore, only to leak detection for the purpose of the scan can guarantee the quality of the filter. There are no standards for photometric scan leak detection, but this method is very effective for quality control of the production process, and the test equipment used is relatively simple, so some manufacturers currently use this method. Photometric scanning test bench is very easy to change into the scanning table, spend some money to buy a laser particle counter on it.
5, high efficiency filter dop method
Test dust source is 0.3mm monodisperse phase dop (plastic industry commonly used plasticizer) droplets. The “quantity” is the degree of opacity of the air containing dop. The instrument for measuring dust is a photometer. The turbidity difference of the gas sample was used to determine the filtration efficiency of the high efficiency filter on the dop particles. Related standards: the US military standard mil-std-282.
