Blowers are rated at standard air: .075 lbs./cubic ft.; 70F at sea level; therefore, pressures corrected to standard conditions must be used when selecting Blowers from rating tables Listed below are the factors to convert to standard conditions or curves. Caution: size motor for highest density (lowest temperature and lowest factor) condition at which it is expected to operate.

The following table was derived by using the head formula.

*Variations in pressure with changes in altitude are directly proportional to the relative density of the air.

HP1 = HP2 x factor where HP1 = horsepower at standard conditions
HP2 = horsepower at operating conditions

P1 = P2 x factor where P1 = pressure at standard conditions
P2 = pressure at operating conditions