THE RESISTANCE TO AIR-FLOW OF FARM BUILDING VENTILATION COMPONENTS

The static air pressure change (pressure drop) across a variety of ventilation components used in agricultural buildings was measured. Twenty-one ventilated wall claddings and ten roof ventilation arrangements were tested. The pressure drops across these items were measured at air approach speeds between 0·05 and 1·7 m/s. Despite the low Reynolds number of the air flow involved, pressure drops varied with the square of air velocity. This allows the pressure drop characteristics of the items measured to be described by a pressure loss coefficient, k. The values of k for the various items tested are given. The use of k, which simplifies the calculation of pressure losses in complex ventilation paths, is described. © 1994 Silsoe Research Institute.