AHP - Air Horse Power and BHP - Brake Horse Power.
Air Horse Power - AHP
Assuming 100% efficiency AHP is the power required to move a given air volume against a given pressure. AHP can be expressed as
PAHP = q dpinWG SG / 6356 (1)
PAHP = Air Horse Power (hp)
q = air flow (cfm)
SG = Specific Gravity Air (= 1.0)
dpinWG = total pressure (in. W.G)
Brake Horse Power - BHP
- Brake horsepower is the actual power delivered to or by a shaft.
The actual power - brake horse power - a fan requires, because no fan is 100% efficient, can be expressed as
PBHP = q dpinWG / μ 6356 (2)
PBHP = Brake Horse Power (hp)
μ = fan efficiency