Abstract: This invention relates to novel apparatus and methods for inserting and positioning a compressible material into a container and for using the container for detecting a specific environmental parameter or combination of parameters, or for determining the effectiveness of a sterilization procedure. Precise positioning of a plug of compressible material in a container has been discovered to provide flexibility necessary for production of indicator systems that vary in their response to sterilizing conditions to reflect the efficacy of sterilizers based on different modes of sterilization and reproduceability necessary for accurate monitoring of each mode. The invention also relates to test indicators containing controlled volumes of compressed, gas-permeable materials and to methods for using test indicators for determining the efficacy of different types of sterilization processes. The test indicator consists of a plurality of interactive enzymes in a container with at least one opening.

Abstract: A spark plug (20, 66) which includes a shell (22) having a ground electrode (24) formed integrally therewith into a predetermined final configuration, an annular insulator (34) with a bore (37) extending therethrough, and an electrode (48) positioned within the bore. The insulator is positioned within the opening of the shell by a press fit operation, and the electrode is also positioned within the bore of the insulator by a press fit method.

Abstract: A method for assembling a spark plug 20, 66 which includes providing a ground electrode 24 on a spark plug shell 22 having a predetermined final configuration and position and then mounting an insulator 34 in the shell. The distance from a step 38 in an insulator bore 37 to the ground electrode is measured. Based upon this measurement and a desired dimension for a spark gap 56, the dimension on a center electrode 48, 68, 74 between a shoulder 50, 76 and a tip 52, 80 is adjusted so that when the center electrode is disposed in the insulator bore with the shoulder seated on the bore step, the tip forms the desired spark gap with the ground electrode. The center electrode then is assembled into the insulator.