Large Scale Tests

Custom Tests and Test Design

SMS is experienced in assisting our customers identify, design, perform and analyze custom test to meet specific needs and concerns. If a standard test exists to answer the issues, they will normally be suggested. However, for some instances, specialized custom testing is necessary to resolve critical issues.

Experimental Machining

The test is used to simulate conditions for propellant machining operations.

In-process Simulations

Where the process is known, appropriate process simulations may be used. However, a change in the process may necessitate re-testing of some or all of the explosives used in the process. Appropriate process simulations may consist of modifications to the standard critical diameter, critical height, internal ignition, or Koenen tests, as well as other in-process classification tests to represent worst-case confinement, configuration, and/or loading in the process.

Large Scale Critical Diameter

Larger scale version of the standard critical diameter test.

Large Scale Critical Height

Larger scale version of the standard critical height test.

Separation Ring Coupon

This test is typically used for rocket propulsion system evaluation. It is used to verify the conditions of motor separation and to measure the explosive reaction for completeness and for unwanted damage.

Skid Tests

Varieties of skid tests have been performed. These tests consist of a customer-supplied skid with a sub-scale or partial process simulation mounted to the skid. The skid is operated remotely and a variety of normal and/or failure scenarios are introduced and tested to verify the operability and safety of the operations involved.

TNT Equivalency

The purpose of a TNT Equivalency Test is to establish the explosive response/output of a hazardous material by comparing it to the known explosive TNT. The Standard TNT Equivalency Test is performed on a relatively large scale with 1 or 2 reference tests using Comp C-4 to assure reliability. Side-on over-pressure sensors (long metal probes mounted on individual stands and pointed at the test sample) are strategically placed at 7 locations about the sample. Two video cameras are used to observe the event. Major fragments from the test vessel are labeled and their throw distances measured.

The standard test vessel pipe assembly consists of a schedule 40 steel pipe with a Length to diameter ratio of 1.0. A 1/8″ steel witness plate is welded on one end of the pipe, with the open end facing up. Photographs are taken of the test configuration before and after each event.

The standard test consists of three material trials. Each trial uses approximately 50 pounds of sample. Two of the 50-lb trials are ignited with a Comp C-4 booster (shock initiation) and the third trial is ignited with either Comp C-4 or a bag igniter (flame initiation). This test is based on a worst-case scenario. Analysis of the data to determine TNT equivalency is included with the test results.

The standard TNT equivalency test can be modified in several ways depending on customer needs. A high-speed camera may also be used to record the event. The booster and sample size may be adjusted. Other modifications can be made to this type of test to make it process-specific. Customer provided hoppers, totes, or containers may be used to provide confinement to the sample in a manufacturing configuration instead of the standard configuration. Process-specific modifications may not represent a worst-case material response.

SMS also performs a TNT Equivalency Screening Test. This test consists of three trials using one pound samples in stainless steel pots on a witness plate. In these tests, a 45-gram booster of Comp C-4 is typically used. This test employs 3 probes to capture the overpressure data. Only one video camera records the event and still photos are not taken. This test provides an inexpensive evaluation of the TNT equivalency for materials with a critical diameter less than approximately 1″. The TNT Equivalency Screening Test is typically used with UN Class 1.1 materials.