Laser dust counters, as precision detection equipment, play a key role in clean environment monitoring in industries such as microelectronics, pharmaceuticals, and biomedicine. It calculates the concentration of particles in the air in real time through the principle of laser scattering. Improper operation not only affects the accuracy of the data, but may also damage the equipment.The Laser Dust CounterThe operating precautions are as follows:
1、 Sampling operation specifications
•Sampling volume control: According to ISO standards, the sampling volume of each sampling point should be ≥ 1L (particles with a diameter of ≥ 0.5 μ m); High cleanliness level environments (such as sterile rooms) need to be increased to 510L to reduce statistical errors. Insufficient sampling can lead to missed detection of large particles, affecting the accuracy of cleanliness assessment.
•Sampling flow rate calibration: The built-in vacuum pump of the instrument needs to be calibrated regularly to ensure that the actual flow rate deviates from the set value by ≤± 5%. If the flow rate decreases, it may be due to a clogged filter element, which needs to be cleaned or replaced in a timely manner. High flow sampling (such as 28.3L/min) can more accurately reflect the cleanliness of the air, but attention should be paid to the maximum sampling concentration limit.
•Sampling interval: When measuring continuously, the interval between adjacent samples should be ≥ 30 seconds to avoid residual particles affecting the next detection, especially in low concentration environments.
•Avoid human pollution: Wear clean gloves during operation and prohibit fingers from covering the sampling port; During the sampling process, it is necessary to stay away from dust generating activities (such as walking or talking) to ensure a stable environment.
2、 Key points for safe operation
•Prohibition of measuring hazardous gases: Do not measure mixed gases that may react (such as hydrogen and oxygen), as these gases may cause explosions inside the counter. If you need to measure such gases, you must contact the manufacturer for professional guidance.
•Prohibition of sampling compressed air: It is prohibited to sample compressed air without high-pressure pressure reducing equipment (such as high-pressure diffusers). All particle counters are designed to operate at atmospheric pressure, and high-pressure gas sources may cause equipment damage.
•Prevent liquids from entering the sensor: Ensure that water, solution, or other liquids do not enter the sensor through the inlet tube to avoid damaging the optical components. In spray or wet environments, keep the inlet pipe at least 12 inches (about 30 cm) away.
•Keep sampling distance: If there are loose particles, dust sources or spray in the test area, keep enough distance to avoid particles and liquids polluting the sensor and pipeline.
3、 Daily maintenance and calibration
•Cleaning and maintenance: Regularly wipe the outer shell with a dry and dust-free cloth. The sampling port can be gently cleaned with a cotton swab dipped in anhydrous ethanol. It is forbidden to rinse directly with water. The internal optical system needs to avoid contamination to avoid affecting the detection accuracy.
•Filter replacement: The pre filter element (located at the front end of the sampling port) is used to intercept large particles (such as ≥ 5 μ m). When the instrument displays the "Prefilter Blocked" alarm, it needs to be replaced in a timely manner, usually every 1000 tests or every 3 months, depending on the frequency of use.
•Performance calibration: Use national standard particle standard materials (such as polystyrene latex balls, particle size 0.3 μ m, 0.5 μ m, 5 μ m) for calibration every year, adjust the instrument particle size channel threshold, and ensure that the detection error is ≤± 10%. Calibration can correct sensitivity changes caused by light source aging or lens contamination.
4、 Other key precautions
•Avoid gas pollution: When sampling, stay away from the gas emitted by the counter to prevent contaminated gas from affecting the detection results. For example, in a closed environment, it is necessary to ensure that the sampling airflow is isolated from the exhaust airflow.
•Peripheral connection specification: When connecting an external printer or external temperature and humidity sensor, the counter must be turned off first; Before performing printing operations, ensure that the printer has printing paper, otherwise it may damage the print head.
•Environmental adaptability: The instrument should be used in a clean environment to avoid dust or vibration affecting the performance of the laser sensor. The working position and the sampling tube inlet should be at the same pressure and temperature to prevent abnormalities in the pneumatic system or condensation in the optical system.
5、 Common problem handling
•Abnormal flow rate: If the flow rate is unstable, check if the filter element is clogged or if the vacuum pump is aging.
•Data bias: There may still be errors after calibration, and it may be necessary to check whether the optical system is contaminated or whether the light source is attenuated.
•Alarm handling: If encountering a "Prefilter Blocked" or similar prompt, immediately shut down and replace the filter element to avoid further damage to the equipment.
By following the above specifications, the reliability of detection data can be improved and the service life of equipment can be extended. Operators need to receive regular training, familiarize themselves with equipment characteristics and emergency response procedures, to ensure maximum efficiency in critical applications.