Pset_DamperPHistory Damper performance history attributes. IfcDamper IfcDamper AirFlowRate Air flow rate. Air Flow Rate Leakage Air leakage rate. Leakage PressureDrop Pressure drop. Pressure Drop BladePositionAngle Blade position angle; angle between the blade and flow direction ( 0 - 90). Blade Position Angle DamperPosition Control damper position, ranging from 0 to 1; damper position (0=closed=90deg position angle, 1=open=0deg position angle). Damper Position PressureLossCoefficient Pressure loss coefficient. Pressure Loss Coefficient