In contrast to those at the Metal Exchange, e.g. at LME, traded metals that conform to standardized qualities, PPM Pure Metals GmbH products are of much higher quality and lower volume. For example, a quality common to the LME corresponds to 99.65%, whereas the quality range of PPM starts at 4N and ends at 8N. In addition, the products must meet a wide variety of individual customer specifications.
What exactly does 4N to 8N mean? In the case described, the “N” stands for “nine” and facilitates the definition of the required quality. Instead of talking about 99.9999% purity, it’s easier to specify 6N purity. Especially since this procedure also protects against expensive misunderstandings – each additional “nine” is in fact associated with increased process costs. In a different and more complicated way, the impurities in the products can also be stated in the ppm or ppb range (ppm = parts per million; ppb = parts per billion).