An energy transfer device (10) is provided that is capable of transferring the energy output from one pyrotechnic device (52) to another device (78) for initiating firing thereof. Device (10) comprises a device housing (12) in which a deformable device insert (14) is received. Device insert (14) comprises a central passageway (34) for transmitting the output from a pyrotechnic device (52), including energy, gasses, and/or solids, to another pyrotechnic device (78). The passageway (34) conducts the pyrotechnic device output to a precise location on the second pyrotechnic device (78) where firing is most effectively initiated. The energy transfer device (10) may be employed as a part of a tool (44) used in well completion operations.

In the context of downhole tools, bulkhead igniter assemblies having snap-on insulators are disclosed. In some embodiments the bulkhead igniter assemblies have a bulkhead with a first end formed with at least one ridge or groove, a pressure block, a setting tool, and a snap-on insulator. The snap-on insulator has an annular body having a tubular channel through a center portion. Ridges or groves on the snap-on insulator mate with ridges or grooves on the bulkhead igniter to hold the snap-on insulator in place on the bulkhead igniter by interaction of the ridge or groove of the snap-on insulator with the ridge or groove on the first end of the bulkhead igniter. Other embodiments are disclosed.