I’ve installed the filter stage in my ELPI™, now I cannot reach 100 mbar, what is the problem?
When filter stage is used the flow is pulled through the filter material. The flow is still controlled by adjusting 100 mbar below impactor stage # 1, which in the case of the filter stage means 100 mbar above the filter. This means that if the filter material is too thick, it will obstruct the flow too much and the pump is not powerful enough to reach 100 mbar above the filter. First check that your pump is efficient enough to pull the flow through the filter material you’re using. Suitable filter/pump combinations can be found in the ELPI™ user manual section 8.6 and in the technical note ‘Substrates and filters for Dekati impactors’. Check that there is only one filter on the filter stage. The filters are very thin so it is quite easy to accidentally place two filters on the filter stage instead of one. If there are two filters on the filter stage, they may together obstruct the flow too much.
