Exhaust Fan and Blower System Evaluation


  • To define the operating rating of an existing exhaust fan or blower system
  • To identify causes for deficient fan performance, excessive dynamic
    vibration, or high noise levels
  • To evaluate the suitability of the fan type, construction and arrangement to the application


  • Measure gas stream volume, density, temperature, suction and discharge pressures, obtain motor brake horsepower
  • Evaluate fan inlet and outlet conditions for velocity pressure profile,
    look for flow disturbances that can cause deficient fan performance
  • Define system curve conditions and superimpose onto fan characteristic curve in order to evaluate possible fan - system interactions that could lead to deficient fan performance
  • Evaluate gas conditioning, scrubbing or filtration equipment operation in terms of their impact on fan performance, especially in light of pressure drop variances or automatic volume flow adjustments
  • Examine any flow control schemes that may be present for stable fan operation throughout the control range required
  • Confirm the suitability of the fan design employed for the duty, including wheel geometry, materials of construction, volume control system, arrangement etc.


  • Provide a written report summarizing the existing fan performance
    and comparing it to the design intent
  • Provide a copy of the manufacturers fan curve at the actual measured rating with the operating point indicated on the curve
  • Give specific recommendations on how best to correct deficient performance through duct or fan modifications, system operating philosophy revisions, or a combination of these