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| BRITISH EXPLOSIVE ORDNANCE |
| Part 2 - Chapter 4 |
| Detonators |
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Sensitive Detonators |
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The sensitive-type detonators are employed with pistols having needle strikers in bombs in which sensitive-type initiation of the explosive train is desired. Sensitive-type detonators differ from the anvil type in that no percussion cap and anvil are provided, and they are made to a standard length of approximately 3.5 inches. Hence, they are in-terchangeable in service bombs, and are selected according to the delay incorporated in them. They may be identified as a class by the stem, which is painted green for a length of one inch from the closed end, and by a green label secured to the detonator plug with shellac and varnished over. |
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Sensitive detonators consist of a stem, and a head into which is screwed a detonator plug. The lower portion of the stem contains a quantity of detonating composition, usu-ally A.S.A. mixture and C.E. In delay detonators, the upper portion of the stem accom-modates a sleeve, which contains a quantity of delay composition, the sleeve being retaining in position by the detonator plug. The initiating detonator consists of a small metal cup having a flash hole through its base. This hole is covered by a thin disc, above which is a small charge of cap composition covered by a metal disc, a paper disc secured with shellac, and a metal washer, which are held in position by lugs turned inwards from the rim of the cup into the washer. Detonators which have the delay composition located directly above the A.S.A. mixture, are termed "inverse loaded". Detonators No. 50 Mk II, No. 51 Mk II, No. 55 Mk II, No. 56 Mk II, and No. 57 Mk II are inverse loaded. This fea-ture allows greater safety in handling. |
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On impact of the fuzed bomb with the target, the pistol striker pierces the initiating detonator and fires the cap composition, which in instantaneous detonators fire the de-tonating composition in the stem, or, in delay detonators, ignites the delay composition in the sleeve, which in turn fires the detonating composition in the stem. |
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The delay of sensitive-type detonators is indicated by a single 3/8-in., or two 3/16-in. colored bands around the head. The color code is as follows: |
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Detonator |
Color | Delay |
| No. 39 Mk I | Yellow | 1 sec. (Obsolescent) |
| No. 39 Mk II | Yellow | 1 sec. |
| No. 46 Mk I | Green | 2 sec. |
| No. 48 Mk I | Red | 0.04 sec. |
| No. 50 Mks I and II | Brown | 0.14 sec. |
| No. 51 Mks I and II | Black | 0.025 sec. |
| No. 52 Mks I, II, III, and IV | White | None |
| No. 53 Mk I | Aluminum | 0.5 sec. |
| No. 54 Mk I | Grey | 3 sec. |
| No. 55 Mks I and II | Blue | 11 sec. |
| No. 56 Mks I and II | White and Red | 0.05 sec. |
| No. 57 Mks I and II | Blue and Yellow | 25 - 30 sec. |
| No. 59 Mk I | White and Black | 0.01 sec. |
| No. 60 Mk I | White and Brown | 0.07 sec. |
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Figure 180 - Examples of the Sensitive-Type Detonators |
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