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Selection strategy of dust particle counter

日期:2021-09-29 00:36
浏览次数:165
摘要:As an instrument for the number and size of particles in the air, the dust particle counter can provide a basis for the assessment of air cleanliness and can also be used to monitor the filtering effect of the filter. The sampling gas is drawn by a sampling pump, and the sampling gas is irradiated with a laser. The flash frequency reflected by the particles represents the number of particles, and the reflected light intensity represents the size of the particles. Since the components in the lase
As an instrument for the number and size of particles in the air, the dust particle counter can provide a basis for the assessment of air cleanliness and can also be used to monitor the filtering effect of the filter. The sampling gas is drawn by a sampling pump, and the sampling gas is irradiated with a laser. The flash frequency reflected by the particles represents the number of particles, and the reflected light intensity represents the size of the particles. Since the components in the laser room are not protected, the laser particle counter should be used in a clean environment to prevent damage to the sensor.

Application range of dust particle counter


The light source is a key component of the dust particle counter, which has a great impact on the performance of the instrument. The light source requires high stability, long life and no interference. The light source of the laser dust particle counter has two kinds of ordinary light source and laser light source. The ordinary light source is an iodine tungsten lamp, which is large in size, high in heating, and short in life. It needs to be preheated after it is turned on.
Then, how to choose? In the selection process, in addition to understanding its classification, we also need to consider many factors: such as its flow rate, sensitivity, particle size range and number of counting channels, the durability of the laser or laser diode, the life of the light source, and maintaining calibration Ability and so on. Before selecting a model, understand that the standard accessories include isokinetic energy probe, tripod, cleaning filter, printing paper, AC cord and manual.

Dust particle counter details


The following is a classification description for the "dust particle counter":
1. According to the test principle: light scattering method test (white light, laser), microscope method test, weighing method test, DMA method test (particle size analyzer), inertial method test, diffusion method test, condensed nucleus method test (CNC) Wait.
2. According to flow: small flow 0.1cfm (2.83L/min) large flow 1cfm (28.3L/min)
3. According to shape and size: handheld, desktop
4. According to the test channel: single channel (measure only one particle diameter); dual channel (test two particle diameters); multi-channel (test multiple particle diameters)
The following is for "how to select the dust particle counter, the specific issues and factors that should be considered:
1. What type of data is expected to be collected? Record this information as simple pass/fail? Or record the information in a spreadsheet or database?
2. What type of environment will the particle counter be used in? Will it be used in an ISO3 clean room for routine particle counting, or will it be used to verify the flow of key processes?
3. Will this particle counter be used to certify clean rooms and from one location to another after testing?
4. Does the operator place the dust particle counter around, place it on the workbench of the key process, or install it on a movable cart?
5. Will it be used for continuous and dynamic clean room particle monitoring? Is the particle counter intended to be connected to an environmental monitoring system?
6. Sensitivity: detectable particles of the smallest size.
7. Counting efficiency: the ratio of the measured particle concentration to the true particle concentration. Use a more sensitive instrument to measure the true particle concentration, and the counting efficiency is 100% under the smallest particle size of the instrument under test. A properly designed instrument should have a counting efficiency of 50%.
8. Zero count level or false count rate: The number of erroneously reported particles using filtered air at the optimal flow rate for a given amount of time. The correct report is the number of particles every 5 minutes. (The expected zero count rate should be less than 1 time every 5 minutes)
9. Flow rate: This is the amount of air passing through the particle counter. This is usually expressed in cubic feet per minute. Common flow rates are 1.0cfm and 0.1cfm. The larger the flow rate, the larger the pump for pumping air and the larger the particle counter.
10. Channel: This is the number of "boxes" into which the particles are placed according to the calculated corresponding size of each particle. The channels are expressed in microns. For example, you might have a 4-channel particle counter. This means that particles can be counted and classified in 4 different channels. Examples of channels are: 0.1μm, 0.2μm, 0.3μm, 0.5μm, 1.0μm, 5.0μm...