First, the count scan method:
The dust source of the counting scanning method is liquid or solid aerosol. For example: DEHS, DOP, polystyrene ball, atmospheric dust and so on.
The local transmittance of the filter being tested can be tested to determine if the filter has local leak defects by measuring whether it exceeds the allowable limits.
Efficient and ultra-efficient filters can also be qualitatively scanned for leak detection using optical particle counters. When atmospheric dust concentration is large enough, atmospheric dust can be selected as a test aerosol for qualitative scan leak testing.
Leakage test should be carried out in the filter rated air flow, sampling port and filter face should be maintained 1cm ~ 5cm distance. When the leak sampling rate is greater than 2.83L / min, the scanning speed should not exceed 8cm / s; When the sampling rate is less than or equal to 2.83L / min, the scanning speed should not exceed 2cm / s, the whole filter Surface scanning.
Second, smoke ray visual method
Smoke through the test, can be used to visually observe the high efficiency filter with or without leakage. The filter is horizontally placed on the tuyere, sealed around, aerosol generated by the aerosol, so that the aerosol particle mass average diameter of 0.3μm ~ 1.0μm.
With the light perpendicular to the filter out of the wind, the filter around and observe the background should be dark, pay attention to filter out the interference around the filter airflow.
Observe the wind surface, if there is smoke plume shows a leak, do not see smoke that no leakage.
Third, the photometer scanning method
Also known as DOP leak detection
Artificial aerosol DOP has been nearly 40 years of history, for some time, due to suspected carcinogenic effects on humans, are often DOS (Dioctylsebaeate Sebacate Sebacate) also known as DEHS [di (2-ethylexyl) sebacate] and PAO (polyaphaolefin polyolefin), etc., but the experimental method is still called “DOP method”, high efficiency filter leak detection PAO generator is usually used in the upstream filter dust, the use of photometers to detect upstream and downstream aerosol concentration To determine whether there is leakage filter. The purpose of dust is due to high dust particles upstream dust concentration is low, only the particle counter in the case of dust is not detected, more difficult to find a leak, need to add dust to be obvious, easy to find leaks.
