Safety Management Services, Inc. (SMS) manufactures a Time-Pressure Test apparatus for clients who require in-house testing to determine if a substance ignition at a pressure attainable in a commercial package will lead to a deflagration.

The primary part of the test apparatus consist of a cylindrical steel pressure vessel with two flats machined on opposite sides. This vessel is internally rebated at both ends and threaded at one end. A side-arm pressure take-off, with an attached diaphragm pressure transducer, is screwed into the pressure vessel face. The end opposite from the side arm is closed with a firing plug fitted with two electrodes. The other end of the pressure vessel contains an aluminum-bursting disk, which is held by a retaining plug with a 20 mm bore. A support stand is used to hold the entire apparatus at the proper attitude during testing.

A section from the two opposites sides is cut and the ends of the flat sides are cut to a 60° angle to the horizontal and welded to the support structure.

The ignition system for the apparatus consists of an electric fusehead and a piece of primed cambric. When preparing the ignition assembly for solids testing, the brass foil contacts of the electric fusehead are separated from its insulator and the exposed insulation portion is cut off. The brass contacts of the fusehead are then fixed onto the firing plug terminals so that the fusehead tip is 13 mm above the firing plug surface. The cambric is pierced through the center and secured with thread over the fusehead. For liquid testing, leads that have been threaded through silicone rubber tubing are fixed onto the fusehead contact foils. The tubing is pushed over the contact foils and the cambric is wrapped around the fusehead. A single piece of PVC sheathing is used to cover the cambric and silicone rubber tubing. As with the solid test apparatus, the leads are fixed onto the firing plug terminals so that the fusehead is 13 mm above the firing plug surface.

The test procedure involves supporting the apparatus firing plug end down with the pressure transducer assembled but without the aluminum-bursting disk in position. A 5.0 g sample is placed in the apparatus so that it is touching the ignition system and the lead washer and aluminum-bursting disk are placed in position. The retaining plug is screwed in tightly and the vessel is transferred to the firing support stand. An exploder dynamo connected to the external terminals of the firing plug is fired and the pressure transducer measures the resulting signal. This signal is then evaluated and recorded. The test is repeated two times.