particle counter

Abstract

The invention discloses a particle counter, which comprises an airtight detection chamber, a gas path and an optical path; the gas path includes a coaxially arranged sampling gas pipe and a receiving pipe fixedly connected with the airtight detection chamber; The light source of the light beam is provided with an incident lens group affixed to the airtight detection chamber and a curved mirror with an opening fixed to the airtight detection chamber in the forward direction of the light beam emitted by the light source. The focal point is located at the intersection of the optical path and the gas path, and the curved mirror is provided with a side light collection and detection device; the outer surface of the sample gas pipe is provided with a coaxial sheath flow tube, and the sheath flow tube and the An annular space for clean sheath flow gas to pass is formed between the sample gas tubes, the gas outlet end of the annular space is flush with the gas outlet end of the sample tube, and a nozzle is connected to the gas outlet end of the sheath flow tube. The invention can effectively prevent the diffusion of the sample gas flow, thereby improving the detection accuracy.

Description

technical field [0001] The invention relates to air cleanliness testing equipment, in particular to a particle counter. Background technique [0002] Many industries, such as medicine, electronics, precision machinery, color tube manufacturing, microorganisms, etc., have high requirements for the cleanliness of the air in the workshop. The cleanliness level of the clean workshop is often determined by the maximum number of particles allowed in the air per unit volume. That is, the particle count concentration is measured. The old US Federal Standard 209E "Cleanliness Levels of Airborne Particles in Clean Rooms and Clean Areas" has been replaced by the new International Standard IS014644-1 "Clean Rooms and Related Controlled Environments, Part 1: Air Cleanliness" on November 29, 2001. Degree classes" and IS014644-2 "Cleanrooms and related controlled environments, Part II: Technical conditions for testing and monitoring for certification of conformity to IS014644-1". In orde...

AI Technical Summary

Problems solved by technology

This method of sampling is simple in structure and easy to implement, but it has obvious defects

It is mainly manifested in two aspects: one is that the particles are easy to accumulate, and the direct-injection sampling structure cannot solve this problem; Dust particles with different particle sizes may get the same scattered light intensity signal when they pass through different positions of the detection spot, which affects the accuracy of detection

In addition, the counters mentioned in the above-mentioned patents have a single detection optical path, and all of them use the side scattered light of the detection particles, but do not detect the relatively strong forward scattered light of the particles.

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