Influence of Measurement Methodologies for the Volumetric Air Flow Rate of Mobile Positive Pressure Fans on Drive Unit Performance

Abstract

Since there are no legally defined testing requirements for mobile positive pressure fans, they may be tested based on methods that do not correspond to their actual operating conditions. Adequate assessment of the technical and operating conditions for this type of equipment is particularly important for equipment used in rescue operations. Such units should be characterized by efficient and reliable operation. This article investigates the influence of measurement methods of the volumetric airflow rate on the performance of a power unit. The article shows that the applied measurement method, whether it is PN-EN ISO 5801 (test conditions in a pipe duct—Method A) or other methods, i.e., ANSI/AMCA 240-15 and testing of the characteristics of the velocity profile (tests in open flow—Method B), can cause differences in the power demand of fans of from 3.2% to 4.5%. The differences in the requirements of propulsion power translate into fuel consumption and emissions of harmful exhaust gases generated by the combustion drive units (4 kW). It was also observed that fans with conventional impellers (W1) show a lower power demand when applying Method B (open flow) tests, while fans with turbo impellers (W2) show a lower power demand when Method A (duct) tests are applied. Comparative analysis of the parameters of the drive unit in the test group of fans without taking into account the measurement method can cause errors of up to about 7.7%, 6.4%, and 2.4% for the power, torque, and speed, respectively.