Optical emission spectrometers When analyzing certain types of metals (such as cast iron, stainless steel, low alloy steel, Hastelloy, Monel, etc.), most of the elements in C, P, S, As, and N need to be tested. The best spectral lines of these elements are in the vacuum ultraviolet range, and the oxygen, nitrogen, water vapor, etc. in the air will strongly absorb the ultraviolet region spectrum, so that the ultraviolet spectral intensity that the spectrometer can measure is sharply weakened, which affects the measured The accuracy and stability of the elements. Therefore, it is necessary to remove the air in the light chamber to achieve a relatively stable ultraviolet region element detection result.
At present, there are two main ways to measure the elements in the vacuum ultraviolet band: 1. The light chamber vacuuming method; 2. The light chamber is filled with argon gas. Purely from the perspective of ultraviolet light transmission, both methods can achieve the measurement of C, P, S, As, N and other elements, but these two technologies essentially represent the technical route of different spectrometer manufacturers, from the following two The technology itself is explained in detail for everyone.
The first type is vacuuming. In this way, the vacuum pump is used to extract the air in the light chamber to form a vacuum inside the light chamber, so that the measurement of C, P, S, As, and N can be realized. The vacuum system is composed of a light chamber, a vacuum pump, a solenoid valve, an optical device, and an electrical component. The light chamber of such a spectrometer is generally large, and has high requirements on the design and manufacturing process of the instrument, and most of the market. Vacuum pumping products are difficult to achieve this level of technology due to technical accumulation and cost control. At present, most vacuum spectrometers on the market have the following problems: The light chamber is deformed due to insufficient compressive strength of the light chamber, and further The data stability is not good; the low-cost procurement of the solenoid valve has a high failure rate, which will cause the oil and gas to be sucked into the light chamber. The lighter one will generate tens of thousands or even hundreds of thousands of maintenance costs, and the serious result will result in the optical system being scrapped; Vacuum pumps that are purchased at low cost have high failure rates and require frequent maintenance, resulting in large equipment maintenance costs and labor costs for the company.
The second type is argon-filled. In this way, an inert gas (generally argon gas) is charged into the light chamber to discharge the air in the light chamber, thereby achieving an optimal analysis state of elements such as C, P, S, As, and N in the ultraviolet region. The argon-filled optical system consists of a light chamber, a pneumatic system, an optical device, and an electrical component. There is no mechanical pump, there is no air tightness requirement like vacuum condition, and the pressure difference between the light chamber and the outside is basically negligible, so the compressive strength requirement for the light chamber is not so high. Therefore, the instrument can be made small, which greatly facilitates the installation and movement of the instrument; at the same time, it avoids the failure rate caused by the vacuum system and greatly reduces the maintenance cost of the user; in addition, the detector used in the general argon-filled spectrometer is CCD or CID not only enables full-element (full-spectrum) detection but is also very easy to extend.
