Excessive reduction in filter thickness is not recommended as this impairs the collection of smaller impurities in the filter pores. Greater thickness means that metal has to displace (travel) in pores a longer way and more often changes flow direction, which improves metal clearing. The filter thickness also directly effects its mechanical strength which is especially important for large filters.

Values in table are for information only since depend on the degree of impurity in liquid metal, its temperature, metallostatic pressure, the shape of the casting system etc. They should be verified in the actual foundry conditions. Under extreme conditions as much as 50% drop in flow capacity may be encountered.

As a rule, for foundries which have no experience with the use of filters, we recommend to begin with ppi 10 porosity filters. The thickness of the filter does not basically effect flow capacity, however, flow velocity will be greater for thinner filters.