Tests for Class 1 (Explosives)

Test Series 1: Is the substance a potential candidate for Class 1 (explosives)?

Gap Test (Zero Gap)

The sample is loaded into the specified steel tubes and placed facing a steel witness plate. A pentolite booster is used to provide a known shock source. The damage to the tube and witness plate is the criteria for a “go” or a “no-go” reaction.

Koenen Test

The Koenen test is used to measure the sensitiveness of solid and liquid substances to intense heat with varied confinement. The sample is placed into a specified sample tube. Flame is applied to engulf the sample tube at a known heating rate. The tube is heated for 5 minutes or until an earlier event occurs. The sample tube is examined to determine whether an explosion occurred.

Varying the orifice plate over the top of the sample tube changes the degree of confinement of the sample. The orifice sizes are changed until an explosion effect occurs, or the substance passes the test with the smallest orifice. Three trials are conducted with the size of orifice plate one size larger than the level where any explosion occurred. This level is considered the limiting diameter. The substance is considered to have explosive properties if the limiting diameter is 1.0-mm or more.

Internal Ignition (10-g bag)

The test determines if a material will explode or detonate when ignited under confinement. The sample is loaded into a pipe with 3000 pound pressure tested forged steel end caps. A 10-gram black powder bag igniter is inserted into the center of the pipe, the pipe is filled with test material and the ends capped. After the igniter is fired, if either the pipe or at least one of the end caps is fragmented into two or more distinct pieces then the test result is positive. The test is considered negative (the material passes) if the pipe is merely split open or the caps are sheared off in one piece. Three trials are performed unless a transition from deflagration to explosion occurs earlier.

Time Pressure Test

The Time/Pressure test measures the rate of reaction of a substance under confinement, and whether that reaction might lead to a deflagration. The test apparatus consists of an instrumented pressure vessel with a rupture disk. An electric match is connected to the electrodes on the firing plug. Black powder (50 mg) is usually added to assure initiation of the substance under test. For samples easily initiated with an electric match, the black powder was omitted. A 5-gram test sample is then placed in the pressure vessel. The pressure vessel is secured and the match is initiated. The pressure is recorded during the reaction. A time/pressure profile is obtained. Numerous explosives show a pressure rise from 100 to 300 psi in less than 600 ms (milliseconds). A substance is definitely considered an explosive if the time interval for the pressure to rise from 100 to 300 psi is less than 30 ms in any one of three trials. The rupture disk provides relief to the pressure vessel above 300 psi.

Test Series 2: Can the substance be excluded from Class 1?

Gap Test (50-mm Gap)

This test is used to measure the sensitivity of a substance, under confinement in a steel tube, to detonative shock. In this test, the sample is contained in a carbon steel tube with the bottom closed by two layers of polythene sheet pulled tightly. The booster charge consists of 160 g of RDX/wax (95/5) or PETN/TNT (50/50). The tube is placed in a vertical position and the PMMA spacer is placed in direct contact with the sheet to seal the bottom of the tube. After positioning the booster charge in contact with the PMMA spacer, the detonator is fixed in place against the bottom of the booster charge and initiated. Two tests are performed unless detonation of the substance is observed.
Reference: Transport of Dangerous Goods – Tests and Criteria

Koenen Test

See explanation above

Internal Ignition (20-g bag)

This test is similar to the internal ignition test described earlier except that a 20-gram bag igniter is used instead of the 20-gram bag. As stated previously, either the pipe or at least one of the end caps must be fragmented into at least two distinct pieces for a positive result. Three trials are performed unless a transition from deflagration to explosion occurs earlier. The test determines if a material will explode or detonate when ignited under confinement.

Time Pressure Test

See explanation above

Test Series 3: Is the material a forbidden substance?

Impact Sensitivity

This test is used to determine whether a material is too sensitive for transport by conducting a screen test. The test is presented as a means used to obtain initial impact data for a manufacturing classification.

ABL Friction Sensitivity

In the ABL Friction Test, the sample is placed on the anvil, and a known force is applied hydraulically through a stationary wheel. A pendulum or motor drive is used to propel the sliding anvil at any of several standard velocities perpendicular to the force vector. Sample initiation is detected by visual means (spark or flame).
Reference: The Transport of Dangerous Goods: Tests and Criteria, second edition, United Nations Test Method 3 (b) (iii) page 108.

Thermal Stability Test

This test is used to determine the reaction of samples when subjected to elevated temperatures for a determined period. The test uses an oven to verify handling, transportation, and storage requirements. The 50 g sample is placed in a constant temperature (explosion-proof) oven at 75 °C for a period of forty-eight hours. The temperature is continuously monitored and recorded. At the completion of the test, the sample is examined for discoloration, weight loss, and dimensional change for evidence of decomposition. This test is part of a series of tests used for establishing hazard classification.

Small-scale Burn Test

This test is used to determine if unconfined samples, once ignited continue burning or transit to an explosion or detonation. A bed of sawdust, containing small samples of test material, is ignited and monitored. The test is a “go” (positive) if explosion or detonation occurs.

Test Series 4: Is the article a forbidden article?

Thermal Stability Test

See explanation above

Twelve Meter Drop Test

This test determines whether a test unit can withstand a free-fall impact without producing any significant fire or explosion hazard. The test unit is dropped from a height of 12m and examined to determine if any ignition or initiation occurred. Three drops are made on the packaged substance or article unless a fire or explosion occur earlier. However, each test unit is dropped only once.
Reference: The Transport of Dangerous Goods: Tests and Criteria, second edition, United Nations Test Method 3 (b) (I) page 101.

Test Series 5: Is the substance a candidate for 1.5?

#8 Cap Test

The No. 8 cap test is used to determine susceptibility of explosives to detonation from the energy delivered by a No. 8 electric blasting cap. The test consists of a sample approximately 60 in3 in size placed in a cardboard tube (liquid samples are placed in a polypropylene bottle). The tube is placed on top of a steel witness plate with a No. 8 cap inserted at the top of the cardboard tube. Sample detonation is determined by examining the witness plate the criteria for detonation is that the witness plate is torn or penetrated.

Deflagration to Detonation Transition (DDT) Test

This test is used to determine the tendency of a substance to undergo transition from deflagration to detonation. In this test, the sample substance to be tested is contained in a carbon steel pipe, capped at one end with a “3000 pound” forged steel pipe cap, and at the other with a 13 cm square, 8 mm thick mild steel witness plate which is welded to the pipe. A 5.0 g black powder igniter, with a nickel-chromium resistance wire loop attached, is placed at the center of the vessel with the resistance wire loop attached to two insulated copper lead wires. These lead wires are fed through small holes in the wall of the pipe and sealed with an epoxy resin. The tube is placed in a vertical position and the igniter is fired by a 15 amperes current from a 20-volt transformer. Three trials are performed unless a deflagration to detonation transition occurs earlier. The test result is considered positive if a hole is punched through the witness plate.
Reference: Transport of Dangerous Goods – Tests and Criteria

External Bonfire Test

This test is used to determine whether a substance, packaged as for transport, can explode if involved in a fire. A stack of packages is placed on a non-combustible surface (steel grate) above a lattice of dried wood soaked with diesel fuel or equivalent source. A wire basket or clamps may be used to hold the articles in place. Sufficient fuel is used to provide a 30-minute fire. The fire is ignited and the material is observed for: a) Evidence of detonation, deflagration or explosion of the total contents; b) Potentially hazardous fragmentation; and c) Thermal effects (i.e. size of the fireball, etc.).

Test Series 6: Is the substance or article a Class 1.1, 1.2, 1.3 or 1.4?

Single Package Test

This test determines if there is a mass explosion hazard of the contents of a single package. The package is placed on a steel witness plate on the ground, and confined using containers that are similar in shape and size to the test package and completely filled with earth or sand. The substance or article is initiated and the following observations are made: evidence of thermal effects, projection effects, detonation, deflagration or explosion of the total package contents. This test is performed three times unless a decisive result occurs earlier (e.g. explosion of the total contents, damage to witness plate beneath the package, etc.).
Reference: Transport of Dangerous Goods – Tests and Criteria

Stack Test

A stack of packages of an explosive product or a stack of non-packaged articles is placed on a non-combustible surface (steel grate) above a lattice of dried wood wetted with diesel fuel. Sufficient wood is used to provide a 30 minute fire. Three aluminum screens are placed 4 meters from the edge of the stack. The fire is ignited and the material is observed for a) Evidence of detonation, deflagration or explosion of the total contents; b) Potentially hazardous projections

External Fire Test

This test is performed on packages of an explosive substance or explosive articles, or unpackaged explosive articles, to determine whether there is a mass explosion or a hazard from dangerous projections, radiant heat and/or violent burning or any other dangerous effect when involved in a fire. A stack of substances or articles is placed on a non-combustible surface (steel grate) above a lattice of dried wood soaked with diesel fuel or equivalent source. A wire basket or clamps may be used to hold the articles in place. Sufficient fuel is used to provide a 30-minute fire. The fire is ignited and the material is observed for: a) Evidence of detonation, deflagration or explosion of the total contents; b) Potentially hazardous fragmentation; and c) Thermal effects (i.e. size of the fireball, etc.).

Safety Management Services
SAFETY MANAGEMENT SERVICES, INC.
1847 West 9000 South, Suite 205
West Jordan, Utah 84088
Phone: 801-567-0456

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Testing Resource

Kirt Sasser
Kirt Sasser, PE
Director of Engineering and Testing
SMS is one of five laboratories authorized by the DOT to witness classification tests for explosives (Class I). We also frequently run in-process tests. Testing is performed at our test site facility at the Tooele Army Depot where we have a thermal lab, sensitivity test lab, and large scale test area. Please contact us for further information at 801-567-0456 or by sending a request.
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