Page 559 - Dust Explosions in the Process Industries

526 Dust Explosions in the Process Industries

7.1 4.2
LAB 0 RATORY TESTS

7.14.2.1
Hartmann Bomb

The Hartmann bomb, described by Dorsett et al. (1960), has been used throughout the
world to assess the maximum explosion pressure of dust clouds for nearly half a cen-
tury. This apparatus, which is illustrated in Figures 7.49 and 7.50, basically consists of
a closed vertical 1.2 liter stainless steel cylinder into which a known quantity of dust is
dispersed as a cloud by a blast of air and exposed to an ignition source.

I / - PRESSURE TRANSDUCER

60 crn3 COMPRESSED AIR
RESERVOIR
SHUT-OFF VALVE
PRESS. REDUCTION VALVE

Figure 7.49 A 1.2 liter Hartrnann bomb to determine pressure development in dust explosions at
constant volume. This version was developed with multinational cooperation and in all essentials
adopted as a standard by the American Society for Testing and Materials (I 988b).

The dispersion mushroom design adopted in a multinational joint effort through the
IEC and shown in Figure 7.46 differs slightly from that included in the standard speci-
fied by the American Society of Testing and Materials (1988b).
The ignition sources used include continuous trains of electric sparks, single syn-
chronized sparks, synchronized chemical ignitors, and glowing resistance wire coils.
Versions of the last two are shown in Figure 7.5 1. To determine maximum pressure, the