Quality inspection of calcium carbide for PCV production by the calcium carbide method and settlement methods
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In the production of PVC via the calcium carbide method, the determination of the quality of calcium carbide has always been a point of dispute between suppliers and demanders. Currently, in addition to traditional manual sampling in its natural state, sampling using belts after the material has been crushed is also employed; however, there are differences in the degree of acceptance for these two methods, which directly affects subsequent calculations of material consumption and settlement procedures. What methods do your colleagues use for acceptance, and what are the regulations regarding settlement? Please share.
Natural sampling faces two problems: firstly, sampling relies largely on manual experience; secondly, only the surface calcium carbide is sampled. As for belt sampling, there are two issues related to it – determining the appropriate sampling time and the frequency of sampling. If regions in the west such as Shanxi, Inner Mongolia, Qinghai, and Xinjiang supply calcium carbide from their own factories, this is not a major issue. If calcium carbide is purchased from an external factory in the southeast, it is best to negotiate with the calcium carbide manufacturer regarding the sampling methods. This national standard specifies the amount of gas generation corresponding to different particle sizes of calcium carbide.
It is better to stick to the method of belt sampling. For long-term suppliers, falsifying tests is not only unethical but also pointless. The settlement is based on gas volume, and the final settlement price aligns with the price fluctuations in the market.