Influence of the Positive Pressure Ventilator Setting Distance in Front of the Doorway on the Effectiveness of Tactical Mechanical Ventilation in a Multistory Building
Abstract:Proper positioning of the positive pressure ventilator is an important aspect of conducting rescue operations. The purpose of this article was to determine the effect of the parameter of the distance of setting up a mobile fan (distance from 1 to 7 m) on the efficiency of implemented ventilation in a multistory building. The volumetric airflow rate was determined by measuring the flow velocity at 120 measurement points on the surface of the window opening (which served as the measurement plane) of a four-story… Show more
“…Positive pressure ventilators producing an air stream with a lower degree of turbulence (e.g. having flow rectifiers), do not lose their momentum intensively (deceleration reduction), are able to blow a stably directed stream over longer distances (even 5–7 m) 28 , 29 . Positive pressure ventilators characterized by greater flow turbulence, e.g.…”
Section: Resultsmentioning
confidence: 99%
“…conventional fan, (if set at distances above 1 m) may work with lower efficiency—the stream generated by the ventilator will begin to slow down as a result of adding additional air from the environment. Such a jet can also change the flow direction and asymmetrically flow onto the surface of the inlet opening 28 , 29 . where: Figure 10 Percentage reduction of air flow depending on positive pressure ventilator setting, where: ( a )—1, ( b )—2, ( c )—3, ( d )—4, L—distance of the fan from the door opening, α—angle of inclination of the impeller axis from the ground.…”
The article aims to determine the influence of fan positioning parameters, i.e., its distance from a door opening (1–7 m) and the angle of inclination of the impeller axis in relation to the ground (0°–18°) on the amount of air flow pumped through a door opening. The experiment was carried out using a mock-up simulating a door opening, on which a measurement plane was located, without the cubic capacity (building structure) behind the door opening. The volumetric air flow stream was determined based on measuring (at 50 measuring points) the velocity of the air stream blown onto the surface of the door opening mock-up. Four commercial positive pressure ventilators, commonly used in rescue operations, with a power of 0.6–6.3 kW were tested. The tests showed that the value of the air flow stream at the most favourable setting (distance in the range of 3–5 m and the angle of the impeller axis to the ground in the range of 5°–12.2°) is included in the range of 18,304 ± 2460 m3/h to about 45,189 ± 4619 m3/h. Such settings cause the air stream to be aimed at the central area of the door opening. Imprecise mobile fan arrangement may reduce the flow rate from 41 to 76% in relation to the most favourable results.
“…Positive pressure ventilators producing an air stream with a lower degree of turbulence (e.g. having flow rectifiers), do not lose their momentum intensively (deceleration reduction), are able to blow a stably directed stream over longer distances (even 5–7 m) 28 , 29 . Positive pressure ventilators characterized by greater flow turbulence, e.g.…”
Section: Resultsmentioning
confidence: 99%
“…conventional fan, (if set at distances above 1 m) may work with lower efficiency—the stream generated by the ventilator will begin to slow down as a result of adding additional air from the environment. Such a jet can also change the flow direction and asymmetrically flow onto the surface of the inlet opening 28 , 29 . where: Figure 10 Percentage reduction of air flow depending on positive pressure ventilator setting, where: ( a )—1, ( b )—2, ( c )—3, ( d )—4, L—distance of the fan from the door opening, α—angle of inclination of the impeller axis from the ground.…”
The article aims to determine the influence of fan positioning parameters, i.e., its distance from a door opening (1–7 m) and the angle of inclination of the impeller axis in relation to the ground (0°–18°) on the amount of air flow pumped through a door opening. The experiment was carried out using a mock-up simulating a door opening, on which a measurement plane was located, without the cubic capacity (building structure) behind the door opening. The volumetric air flow stream was determined based on measuring (at 50 measuring points) the velocity of the air stream blown onto the surface of the door opening mock-up. Four commercial positive pressure ventilators, commonly used in rescue operations, with a power of 0.6–6.3 kW were tested. The tests showed that the value of the air flow stream at the most favourable setting (distance in the range of 3–5 m and the angle of the impeller axis to the ground in the range of 5°–12.2°) is included in the range of 18,304 ± 2460 m3/h to about 45,189 ± 4619 m3/h. Such settings cause the air stream to be aimed at the central area of the door opening. Imprecise mobile fan arrangement may reduce the flow rate from 41 to 76% in relation to the most favourable results.
“…2023 studied identical ventilator units. During these tests, it was shown that the effectiveness of such a ventilator decreases as the positioning distance relative to the doorway increases 10 . The same conclusions were also proposed by Lougheed et.…”
Section: Volumetric Airflowmentioning
confidence: 99%
“…The obtained results, confirmed that in the context of flow resistance, in addition to secondary pressure losses associated with friction against the facility's interior walls, interaction of stair treads and changes in flow direction, the main sources of flow resistance in the facility are constrictions (openings in the ceiling) between floors. In addition, the authors showed that if the intention to be achieved during the rescue operations is to increase the value of the flow rate, it is more important to reduce the resistance to flow in the building or increase the value of the pressure than to increase the discharge area [10][11] . An interesting full-scale study of positive pressure ventilators was also conducted by Lambert et al in 2018. The tests concerned the evaluation of the flow rate of a set of ventilators, on the site of a facility that constitutes subway stations.…”
Section: Introductionmentioning
confidence: 99%
“…Achieved air flow rates for the tested configurations(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11), where AVGarithmetic mean of the flow rate (m 3 /h) and confidence interval (p=0.05).…”
The effectiveness of mechanical tactical ventilation during rescue and firefighting operations can be improved by multiplying the number of positive pressure ventilators. Such action can shorten the time of the operation, improve its execution, and reduce the energy consumed by the ventilators used during the operation. In order to determine the proper conditions for the two ventilators to work together, tests were conducted on their positioning relative to the doorway. These values were determined from the flow parameters (flow rate and static overpressure generated). A set of conventional rotor ventilators (each with an output of 4.4 kW) was tested. The article performs an analysis of the magnitude of flow parameters depending on the setting of the positive pressure ventilator. Proper positioning of the set of ventilators can increase the flow rate through the facility by up to 32% and the pressure by 50%. The analysis conducted in the article can be used as recommendations for rescue teams for the proper selection of the setting of the positive pressure ventilator during firefighting operations of internal fires.
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