Disclosed is a process for removing coarse solids and fine solids from a gas, which includes wetting the coarse solids and fine solids in a first chamber thereby separating the coarse solids and fine solids from the gas. For the purpose of securely holding drills of various shapes, it is provided that at least one holding part is elastically deformed to envelop the drill to be held. Each differential channel includes a pair of magnetic field sensing elements and has a respective sensing axis defined by those magnetic field sensing elements.