Particle counter

Abstract

The invention discloses a particle counter which comprises a hermetic detection chamber, a gas path and a light path, wherein the gas path comprises a sample injection gas pipe and a receiving gas pipe which are coaxially arranged and fixedly connected with the hermetic detection chamber; the light path comprises a light source which emits divergent beams; an incident lens set and a curved mirrorwith an opening are sequentially arranged along the forward direction of the beams emitted by the light source, and both the incident lens set and the curved mirror are fixedly connected with the hermetic detection chamber; the focal point of the curved mirror is positioned at the intersection of the light path and the gas path, and the curved mirror is provided with a lateral light collection anddetection device; the sample injection gas pipe is externally sleeved with a sheath flow pipe being coaxial with the sample injection gas pipe, and an annulus space which allows clean sheath flow gasto pass through is formed between the sheath flow pipe and the sample injection gas pipe; the gas outlet end of the annulus space is parallel and level to the gas outlet end of the sample injection pipe; and the gas outlet end of the sheath flow pipe is connected with a nozzle. The invention can effectively prevent the diffusion of sample gas flows, thereby improving the accuracy of detection.

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 The old US Federal Standard 209E "Cleanliness of Airborne Particles in Clean Rooms and Clean Areas" has been replaced by the new international standard ISO14644-1 "Clean Rooms and Related Controlled Environments, Part 1: Air Cleanliness" on November 29, 2001 Degree classes" and ISO14644-2 "Cleanrooms and related controlled environments, Part 2: Specifications for testing and monitoring for certification of conformity to ISO14644-1". In order to be in line...

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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