Time Pressure Apparatus

Time-Pressure Apparatus

Safety Management Services, Inc. (SMS) manufactures a Time/Pressure test apparatus for clients who require in-house testing to determine the effects of igniting a substance under confinement.

The Time/Pressure apparatus consists of an instrumented pressure vessel equipped with a replaceable rupture disc. A test sample (5 grams maximum) is placed in the pressure vessel and ignited by flame (UN Test 1(c)(i) or 2(c)(i)) or heated Nichrome (NiCr) resistance wire (UN Test O.2). Upon ignition, the combustion gases pressurize the instrumented test vessel until the rupture disk bursts (~400 psi (2760 kPa) gauge).

The test results are interpreted in terms of whether a gauge pressure of 300 psi (2070 kPa) gauge is reached, and, if so, the time taken for the pressure to rise from 100 psig (690 kPa) to 300 psig (2070 kPa) gauge. The sample has the ability to deflagrate rapidly and is an explosive regulated for transport if the pressure rise time is less than 30 msec.

The following time/pressure profiles are representative of instrumented UN Test 2(c)(i) results:

Sample A: Fail (2.4 msec rise)

Sample B: Pass (52.6 msec rise)

Sample C: Pass (34.3 msec rise)

The apparatus is supplied with the following (subject to availability):

  • A firing plug for Time/Pressure tests (low ignition posts) and Oxidizing Liquids tests (high ignition posts)
  • Static (slow rise time) and dynamic (fast rise time) 500-psig pressure sensors with associated amplifiers (0 – 5 Volt output)
  • USB-based data acquisition system (DAQ) with pre-configured netbook
  • Test supplies: lead washers, rupture discs, NiCr resistance wire
  • Connection cabling
  • Optional: DC regulated power supply and firing line