Xylem BMAID R4 - Manual (Page 45)

PAGE 45
Residential Water Systems
CentriPro
baSIC formulaS aND SymbolS
Water Horsepower = GPM x 8.33 x Head = GPM x Head
33000 3960
Temperature conversion
DEG. C = (DEG. F – 32) x .555
DEG. F = (DEG. C x 1.8) + 32 Area of a Circle
A = area; C = circumference.
A = π r
2 ; π = 3.14
C = 2πr
r
CIRCLE
d
Where:
GPM = Gallons per Minute
8.33 = Pounds of water per gallon
33000 = Ft. Lbs. per minute in one horsepower
Head = Difference in energy head in feet (field head).
Laboratory BHP = Head x GPM x Sp. Gr.
3960 x Eff.
Field BHP = Laboratory BHP + Shaft Loss
Total BHP = Field BHP + Thrust Bearing Loss
Where:
GPM = Gallons per Minute
Head = Lab. Head (including column loss)
Eff. = Lab. Eff. of Pump Bowls
Shaft Loss = HP loss due to mechanical friction of lineshaft bearings
Thrust Bearing Loss = HP Loss in driver thrust bearings
(See (1) below under Misc.)
Input Horsepower = Total BPH
Motor Eff.
Motor Eff. from Motor mfg. (as a decimal)
Field Efficiency = Water Horsepower
Total BHP
Water HP as determined above
Total BHP as determined above
Overall Plant Efficiency = Water Horsepower
Input Horsepower
(See (2) below under Misc.)
Water HP as determined above
Input HP as determined above
Input Horsepower = BHP = 4.826 x K x M x R = 1.732 x E x I x PF
Mot. Eff. T 746
BHP = Brake Horsepower as determined above
Mot. Eff. = Rated Motor Efficiency
K
= Power Company Meter Constant
M = Power Company Meter Multiplier, or Ratio of Current and Potential
Transformers connected with meter
R = Revolutions of meter disk
T = Time in Sec. for R
E = Voltage per Leg applied to motor
I = Amperes per Leg applied to motor
PF = Power factor of motor
1.732 = Factor for 3-phase motors. This reduces to 1 for single phase motors
Electrical
Miscellaneous
Kilowatt input to Motor = .746 x I.H.P. = 1.732 x E x I x PF
1000
KW-Hrs. Per 1000 Gallons of = HD in ft. x 0.00315
Cold Water Pumped Per Hour
Pump Eff. x Mot. Eff.
(1) Thrust Bearing Loss = .0075 HP per 100 RPM per 1000 lbs. thrust.*
(2) Overall Plant Efficiency sometimes referred to as “Wire to Water” Efficiency
*Thrust (in lbs.) = (thrust constant (k) laboratory head) + (setting in feet x shaft wt. per ft.)
Note: Obtain thrust constant from curve sheets
Discharge Head (in feet of fluid pumped) = Discharge Pressure (psi) x 2.31
Sp. Gr. of Fluid Pumped
D = diameter
r = radius
tErmS aND uSablE formulaS