No. An industrial shock absorber cannot be used as a via ferrata set, because:
- Via ferrata sets are intended to absorb falls that exceed a person's height. EN 355 (industrial absorbers) mentions a drop test that involves a 100kg mass being dropped from 1.75m such that the final resultant force cannot exceed 6kN. The EN 958 (via ferrata sets) drop test involved a 80kg mass being dropped from a height of 5m, such that the maximum elongation and resultant force cannot exceed 12m and 6kN, respectively.
- Static force tests are different for the two categories: industrial absorbers must withstand 3 min subjected to a constant 15kN force. Ferrata sets must withstand a very different test: a force strong enough to generate an elongation of 1 to 1,5 cm per min is applied to the absorber and the resultant force measured at the tip. It cannot exceed 1.2kN.
- EN 958 doesn't mention any tests related to harsh environments (this is a constant amongst climbing equipment norms - it looks like no one gives a damn about environmental test). EN 355 mentions a salt water test, to be performed during one or two days, where rusting/functionality are inspected.
These are the main differences between those norms. There are many small differences but I don't think they are worth mentioning. The main point is: an industrial shock absorber is not supposed to work for a fall that is not industrial, and in industry no one climbs a ladder without the constant presence of anchor points. They come as frequently as human height. Ferrata sets, in their turn, are meant to catch someone that slipped from a significant height.
P.S.: notice that even though industrial sets cannot be used for via ferrata, it looks like via ferrata sets can be used for industrial mild environments (with the right carabiners, that is, the ones that follow NFPA 1983, not EN 12275).