STANAG 4490 electrostatic discharge sensitivity testing of explosives

What it is

STANAG 4490 is the NATO Standardization Agreement on explosives electrostatic discharge sensitivity testing. It is the first edition, promulgated 19 February 2001. Most STANAGs are short covers pointing a nation at a separate Allied Publication that carries the technical requirements. STANAG 4490 lists "Related documents: None"; its own annexes carry some of that content directly, though not for both of the tests it covers.

Two tests, treated differently

The agreement's own aim is "to standardise the test procedure to provide information on the electrostatic discharge sensitivity of explosive materials," and participating nations "agree to distinguish spark tests and large scale electrostatic discharge test, for determining the electrostatic discharge sensitivity of explosive materials." The two are not handled the same way.

The small scale "spark" test, covered in Annex A, is not standardised by this STANAG at all: "there is no standardised equiment for this test. Each participating nation will use its national test described in AOP-7," a separate publication this STANAG names but does not contain. What is common is only the reporting: ratifying nations agree that data for this test "will have to be provided by using the data exchange formats described in Annex A, as well as reference data," because it is needed for a material's qualification.

The large scale test, covered in Annex B, is different. Here, participating nations "agree to accept one test as standard procedure and to use the data exchange formats as provided in Annex B," so unlike the spark test, one method is common to every ratifying nation. Its data, too, "is required for qualification of explosive materials at ambient temperature and, if relevant, in temperature conditions corresponding to use in operation."

Why a shared large scale method exists

The agreement's own background explains the reasoning. Existing spark tests use small samples and simulate the discharge a charged person can produce, and nations' own historical data from them has been satisfactory for that purpose, "so there is no need to standardize the equipment." But such tests do not explain certain accidents that trace back to static charge building up on poorly conducting surfaces, such as plastics, in contact with explosive material, which "can lead to arcing and catastrophic accidental ignition." That is the gap the large scale test in Annex B was written to close, as a common, standardised procedure rather than a further national variation.

What the large scale method covers

Annex B's own scope is that the method "may be used for the characterization of electrostatic discharge sensitivity of energetic materials such as non conductive high explosives, rocket motor and gun propellants," and that "It is not applicable to primary explosives and pyrotechnics." This page does not describe the apparatus, the sample preparation, the test procedure, or the values that separate one outcome from another. That detail is exactly what a competent test laboratory needs from the STANAG's own Annex B, not from a summary of it.

How it binds

A STANAG binds a nation, not a company. This one "has been ratified by nations as reflected in page iii," and is "implemented when a nation has issued the necessary orders/instructions putting the contents of this agreement into effect." Ratification and implementation are separate steps, and a nation cannot depart from the agreement quietly: "No departure may be made from the agreement without consultation with the tasking authority." National staffs are the ones addressed directly: they "are requested to examine page iii of the STANAG and, if they have not already done so, advise the Defence Support Division through their national delegation as appropriate of their intention regarding its ratification and implementation." None of this reaches a supplier directly. A company meets STANAG 4490 only where a contract, a tender, or a national requirement calls for electrostatic discharge sensitivity data produced under it.

What it does not cover

STANAG 4490 describes no certification or audit scheme of its own, and no company or product is certified under it. Both annexes tie their data to a material's "qualification," but the agreement does not say who reviews that data or grants qualification, and a qualification decision made about a material is not a certificate an organisation can hold. The only other document the agreement names is AOP-7, for the small scale test's own national procedure.

Standards it references

• AOP-07Background