- Author
- Bryant, R. A.
- Title
- Predicting Inward Leakage for Negative Pressure Conditions in a Firefighter Respirator.
- Coporate
- National Institute of Standards and Technology, Gaithersburg, MD
- Report
- Poster Session 1,
- Book or Conf
- Interflam 2010. (Interflam '10). International Interflam Conference, 12th Proceedings. Poster Session 1: Fire and Emergency Response. July 5-7, 2010, Nottingham, UK, 1-9 p., 2010
- Keywords
- respirators | fire fighters | leakage | pressure | self contained breathing apparatus | face protection | experiments | equations | sampling
- Identifiers
- sequence of sampling by PORTACOUNT; volume flow rate; flow across resistive flow paths; respirator fit factor
- Abstract
- An analytical model of the flow across a resistive flow path such as an orifice or pipe was applied to predict the inward leakage in an SCBA facepiece during· a steady negative facepiece pressure. Starting with a range of negative pressure conditions assembled from the literature, the model was used to estimate leakage rates with respect to the size of the leak. The results ofthe model were also used to make quantitative estimates of the protection level of the respirator. Experiments were designed to induce a continuous below-ambient pressure inside the facepiece of a pressuredemand SCBA attached to a head form. Negative facepiece pressure measured in the presence of a leak correlated with measured fit factor. The results show that the analytical model generated reasonable estimates of leakage rates during conditions of negative pressure inside the facepiece. Thus the analytical model performed well for constant flow conditions, demonstrating the potential to predict a momentary compromise in respirator protection during momentary negative facepiece pressure conditions.