Equations & Definitions

Formulas and Definitions

VP	=	(FPM/4005)2
(Q) CFM	=	Cubic Feet per Minute
TP	=	Total Pressure
SP	=	Static Pressure
VP	=	Velocity Pressure
(V) FPM	=	Feet per Minute
P	=	Differential Pressure
PS	=	Static Differential Pressure
PT	=	Total Differential Pressure
(A) Area Factor	=	Dimension in Square Feet
VP	=	TP - SP
TP	=	SP + VP
SP	=	TP - VP
CFM	=	FPM x Area Factor
PT	=	TP1 - TP2
PS	=	SP1 - SP2
P	=	(CFM / K)2
FPM	=	CFM / Area Factor

Water Coils

MBH	=	1000's of BTU's per Hour
BTU	=	British Thermal Unit
GPM	=	Gallons per Minute
T	=	Temperature Differential
T	=	927 x MBH / CFM
H2OT	=	2.04 x MBH / GPM

Electric Coils

KW	=	Kilowatts
T	=	Temperature Differential
KW	=	CFM x T / 3160
T	=	KW x 3160 / CFM

Power

W	=	Watts
A	=	Amps
HP	=	Horsepower
V	=	Volts
E1	=	Efficiency
PF	=	Power Factor

Power D-C Circuits

W	=	V x A
A	=	W / V
HP	=	V x A x E / 746
V	=	746 x HP / W

Power A-C Circuits (Single Phase)

PF	=	W / V x A
A	=	746 x HP / V x E x PF
E	=	746 X HP / V x A x PF
KW	=	V x A x PF / 1000
HP	=	V x A x E x PF / 746

Power A-C Circuits (3 Phase)

PF	=	W / V x A x 1.732
A	=	746 x HP / 1.732 x V x E x PF
E	=	746 x HP / V x A x PF x 1.732
KW	=	V x A x PF x 1.732 / 1000
HP	=	V x A x 1.732 x E x PF / 746