N020
Establishing
Air Flow Patterns inside Respiratory Protection
Devices
Sven van der Gijp,
Coen van Gulijk and Rutger Gaasbeek
TNO PML
Lange Kleiweg 137,
Tel: +31 15 284 3402 Fax: +31 15 284 3963
e-mail: gijp@pml.tno.nl
ABSTRACT
On various levels air flow
patterns inside respiratory protection devices determine the functionality of
the protective device. Aspects such as fogging of eye
glasses, heat stress, the efficiency of the filter and
the method to perform fit testing
depend on the air flow. In this paper a digital gas mask is described, which
was developed using 3D-scanning techniques and a CAD/CAM model.
The model can be
placed on a representative digital head of a person;
Both models combined, allow the calculation and
visualisation of air flow patterns inside the respirator. Air flow calculations were
performed using computational fluid dynamics. This method allows the localization and
analysis of dead spaces inside a respirator. In addition the outcome of the computerised
respirator was validated by measurements of the air flows.
For these measurements,
high speed video imaging of smoke inside respirator was used, as well as Laser
Doppler Anemometry. The measurements
show the circular flow patterns during the breathing cycle behind the eye
glasses.