Netter vibration pkl pneumatic impactors spring driven piston netter vibration pkl 7406 the pkl 7406 is a pneumatic impactor that uses a spring driven piston to directly impact on the surface on which the impactor is mounted the piston creates an impact similar to that of a hammer and can produce a sequence of 10 consecutive impacts at a rate of 15 impacts per minute and 180 impacts per hour this impactor is suitable for applications such as knocking stubborn residues and cleaning pipes