Identification and Evaluation of Technical and Operational Parameters of Mobile Positive Pressure Ventilation Fans Used during Rescue Operations

Abstract

Aim: The aim of the article is to indicate the essential technical and operational parameters of mobile fans and to present the proposed testing method- ologies (as well as dedicated infrastructure) allowing to confirm the indicated features. Project and methods: In many places around the world, scientists conduct tests related to the use of mechanical tactical ventilation with the use of mobile positive pressure ventilation fans. These devices are used by fire protection units, among others, for the removal of thermal decomposition products resulting from fires, posing a threat to people staying in construction facilities during events and hindering rescue operations. Achieving the expected effects through the use of mechanical tactical ventilation depends on many factors, among others, on the appropriate technical parameters and the ability to use the fan. Describing the essential features that should be characterized by the devices in question, attention in particular should be paid to: mobility, durability, reliability and effectiveness. To confirm these features, mobile fans should be tested using properly validated test methodologies. This publication presents a draft of the test program that allows to confirm the effectiveness of mobile fans, i.e. aerodynamic efficiency (flow rate), stream shape (area of the effective speed distribution), operating time, noise, weight and dimensions. Conclusions: Mobile fans used by fire protection units are an important tool supporting the effectiveness of rescue operations. However, in order for them to be used in an optimal way, it is necessary to comprehensively examine the technical parameters, and then – adequately to these parameters – to develop appropriate procedures for their use. In the context of the aforementioned testing, despite the large scientific achievements in this field, there are still areas that require improvement, with particular emphasis on standardized testing methodologies and the measurement infrastructure dedicated to them. For this reason, the authors indicated important technical and functional features that determine the effectiveness of mobile fans and recom - mended selected methods on the basis of which these features can be verified. The intention of the project is to provide rescuers with greater comfort when choosing and using the devices in question. The basis for this comfort is to be aware of the availability of equipment with confirmed functional characteristics and the possibility of referring to the developed guidelines for the proper use of fans in accordance with their parameters. Key words: mobile positive pressure ventilation fans, tests of mobile fans, functional properties of fans Article type: review article

Experimental studies of the influence of mobile fan positioning parameters on the ability to transport the air stream into the door opening

“…Rejecting the results for the two most unfavourable distances and tilt angles of the impeller axis (i.e., extreme maximum and minimum positions) in the analysis, the greatest reduction of the flow rate ranges from 5 to 19% depending on the fan type. The differences in the volume of air flow are related to the change in the flow direction (the collision with an obstacle in the form of a door opening frame) and the quality of the generated air stream 7 . According to Cimolino et al 17 changing the angle of the blown air can increase the flow rate by up to 30%.…”

“…cars or garbage containers), ventilation of hard-to-reach places (where people stay)—with the use of electric fans 6 . Referring to devices (including positive pressure ventilators) used in rescue operations, it is indicated that they should be characterized by high operational reliability, efficiency, and functionality and should have little impact on the user 6 , 7 . In many countries, devices used in rescue operations are subject to special testing procedures 8 .…”

“…The values of the volumetric flow test results will vary depending on the test conditions. As shown by the analyses conducted by Kaczmarzyk et al in 2022, the open-air flow measurement method better reflects the actual conditions of the device use, and the driving power demand, depending on the test method, may vary from 3.2 to 4.5% 7 , 8 . Additionally, Fritsche et al in 2018 indicated that the manufacturers’ declared volumetric airflow rate values for mobile fans may differ from actual ones due to the lack of a standardized methodology for testing this type of equipment 11 .…”

“…In the same year, the authors, using a Fire Dynamics Simulator (FDS 5.0), conducted research on the impact of the rescue capabilities of fans depending on the structural layout of a building, wind conditions and the arrangement of the fans, demonstrating that the effectiveness of PPV decreases with increasing wind speed 14 . Mobile positive pressure fans are characterized not only by air flow but also by the shape of the air stream (the surface of the effective distribution of the stream), which can significantly affect the ability to force air into a building 7 . Additionally, it can be noted that many fans of a commercial design can adjust the inclination of the impeller axis in relation to the ground.…”

Problems of operation of positive pressure ventilators on the basis of surveys of Polish officers of the State Fire Service

“…Taking into account the important role of rescue ventilators in the implementation of rescue operations, CNBOP-PIB (Scientific and Research Centre for Fire Protection—National Research Institute) in Józefów, Poland, has begun to implement the construction of a research infrastructure allowing the evaluation of the most important features determining the effectiveness of this type of equipment. Among the most important characteristics that can determine the effectiveness of rescue operations are: the size of the generated jet; the area of jet dispersion as a function of distance; noise; the length of operating time, as well as the weight and dimensions of the device 42 . The developed range of the apparatus is a flow tunnel made in accordance with the requirements of ANSI/AMCA 240-22 and PN-EN ISO 5801 43 , 44 .…”