Skip to main content

Useful Equations


Coil Face Area (sq. feet) = Fin Height (inches) x Fin Length (inches) / 144
SCFM (ft3/min) = ACFM (ft3/min) x Density of Air (lb/ft3) / 0.075
Face Velocity (ft/min) = SCFM (ft3/min) / Face Area (sq. feet)

Air Capacity

Total Capacity (Btu/hr) = 4.5 x SCFM x Change in Enthalpy (Btu/lb)
Sensible Capacity (Btu/hr) = 1.08 x SCFM x Change in Drv Bulb Air Temperatures (°F)
Refrigeration Capacity (Tons) = Total Capacity (Btu/hr) ÷ 12,000

Water / Fluid Capacity

Total Capacity (Btu/hr) = 500 x GPM x Change in Water Temperatures (°F)
Fluid (non-water) Capacity (Btu/hr) = 500 x GPM x Specific Gravity (lb/ft3) x Specific
Heat (Btu/lb-°F) x Change in Fluid Temperatures (°F)


Condensate (lbs/hr) = Capacity of Coil (Btu/hr) ÷ Latent heat of vaporization @ steam pressure (Btu/lb)

Need a quote for a coil or heat exchanger design or service?
We have what you need.