ISRP 2000 abstract
| Presenter/author | Title | Abstract |
| Richardson,
Grant Stewart
Scientific leader, DERA Porton Down, Salisbury, UK |
The Effect of Testing Respirator Components with Real Breather Patterns as Opposed to Constant or Sinusoidal Flow | Current standards
outlining the test methods for both military and industrial respirators
require specific components such as canisters and outlet valves to be
tested under constant or sinusoidal breathing regimes. Given, (i) the
performance of such components is dependent on the test flow conditions,
and (ii) the occurrence of high peak flows that are observed during
actual breathing cycles, potential exists for component performance to
differ markedly when investigated under real breathing patterns compared
to other less demanding flow regimes. The advancement of breathing
machine technology at DERA Porton Down permits the accurate recording of
actual breather flows, which in turn may be reproduced using a digital
breathing machine. Consequently, canisters and outlet valve assemblies
can be rigorously tested using a series of “real” breathing patterns
representing low, medium and high work rates. In addition, other
activities such as talking can be mimicked and incorporated into the
test regime.
This paper reports on the performance of canisters as regards (i) aerosol penetration and vapour breakthrough time, and (ii) the dynamic leakage of the outlet valve using various test flow regimes. For each work rating, the minute volume is maintained as a constant so that a true comparison may be made. Methods for deriving actual flow patterns from internal respirator pressures are also discussed. Adopting this approach permits breathing patterns to be easily recorded using a single, miniature pressure transducer as opposed to a complex and cumbersome flow arrangement. |