A.C. Delay Igniter Mk. I:

The initiating mechanism used with the Rigid Limpet i a chemical type long delay device, consisting of a brass body containing a spring-loaded striker. The head of this striker is sunk in a celluloid disc, retaining the striker under spring compression.

Immediately above the celluloid disc are located cotton wadding and a glass am-poule of solvent accommodated in an enlarged recess in the body. The top of the body is threaded externally to receive a threaded cap. Screwed into the center of the cap is a threaded spindle which bears on a rubber sealing disc. To the top of the spindle is attached a wing to permit manual operation. A safety pin pierces the threaded spindle and the cap, preventing the spindle from being screwed down as long as the pin is in place.

The device is put in operation by removing the safety pin and screwing down the threaded spindle, crushing the ampoule and allowing the solvent to saturate the cotton wadding and work on the celluloid disc. Eventually the celluloid is sufficiently softened to release the striker, which is then forced by its spring into the detonator threaded to the lower end of the body.

Overall Length

Detonator Length

Max. Body Diameter

Delay Times at 20° C.

(Delay times will increase

at temperatures above 20;

decrease, below.)

Violet ampoule: 4½ days