UN GAP TEST apparatus is designed and used to measure the ability of a substance, under confinement in a steel tube, to propagate a detonation by subjecting it to the detonation from a booster charge.
The explosive to be tested is subjected to the action of the shock wave of a known pressure. Such wave is generated by means of a booster and shock wave pressure attenuator.

Whether or not the shock wave caused the complete detonation of the explosive can be concluded on the basis of the mechanical effects produced after the detonation of the explosive hole e.g. cutting in a steel plate.

The UN GAP TEST is a sensitivity test at which sample is exposed to the shock wave is weakened by passing through a barrier of known properties (usually PMMA is used). The function of this barrier is not only to weaken the shock wave from the donor charge, but also to isolate the acceptor charge from the detonation products (hot gases, burning particles).



A shock wave, which can be generated in various ways in an explosive, frequently serves as a tool for the initiation of explosives. The Gap test enables the determination of the minimum shock wave pressure that can cause complete detonation of the tested explosive.



  • UN GAP TEST apparatus is designed to comply with requirements of the following standards of testing:
  • UN Recommendation on the Transport of Dangerous Goods, Manual of Tests and Criteria, United Nations, New York,1995, Test 1 (a) and 2(a).

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