Definitions

  • Electrical
    • E = Volts – Potential
    • I = Amps – Current
    • R = Ohms – Resistance
    • P = Watts – Measure of Power
    • RFLA = Rated Full Load Amps
    • CLFA = Corrected Full Load Amps
    • MOA = Motor Operating Amps
    • NLA = No Load Amps
    • Pf = Power Factor
    • Eff = Motor Efficiency
    • BHP = Brake Horsepower
  • Temperature
    • F = Fahrenheit
    • 32 = Freezing @ std conditions
    • 212 = Boiling @ std conditions
    • -459.6 = Absolute Zero
    • C = Celsius or Centigrade
    • 0 = Freezing @ std conditions
    • 100 = Boiling @ std conditions
    • -273.16 = Absolute Zero
    • K = Kelvin
    • 0 = -273.16 C
    • R = Rankine
    • 0 = -459.60 F
  • Energy (British Units)
    • BTU = British Thermal Unit
    • BTUH = British Thermal Units/Hour
    • MBH = 1,000 BTU’s
    • Ton = 12,000 BTU’s
    • THERM = 100 Cu.Ft. Gas = 100,000 BTU’s
    • MCF = 1,000 Cu.Ft. Gas = 1,000,000 BTU’s
    • 1 HP = 2,545 BTUH
    • 1 HP = 550 Ft Lb/Second
    • 1 HP = 746 Watts
    • 1 HP = .0761 Boiler HP
    • Boiler HP = 33,450 BTUH
    • 1 FT Hd = Ft.Lb./Lb Water
  • Air Movement
    • V = Velocity in FPM
    • FPM = Feet per Minute
    • SP = Static Pressure (Potential Energy)
    • VP = Velocity Pressure (Dynamic Energy)
    • TP = Total Pressure (Sum of SP & VP)
    • ME = Mechanical Efficiency
    • P = Pressure in Static
    • C = C Value (Loss Coefficient)
    • TS = Tip Speed (Peripheral Velocity in FPM)
  • Water Movement
    • V = Velocity in FPS
    • FPS = Ft per Second
    • TDH = Total Dynamic Head
    • Ft Hd = Feet of Head
    • H = Feet of Head
    • NPSH = Net Positive Suction Head
      • (Absolute Pressure including atmospheric)
    • CV = Control Valve GPM Flow @ 1 Ft Hd
    • WHP = Water Horse Power
    • Sp.Gr. = Specific Gravity
  • Water Properties
    • Cp = Specific Heat = BTU’s/Lb > (1) Degree F
  • Air Properties = 78% Nitrogen, 21% Oxygen, 1% Argon
    • Std Air = .075 Lb/Cu Ft @ 70 F
    • Std Air = 13.333 Cu Ft/Lb @ 70 F
    • RH = Relative Humidity (% of Saturation)
    • v = Specific Volume (Cu Ft/Lb of Air)
    • D = Density (Reciprocal of Specific Volume)
    • SH = Sensible Heat Factor (Same as SHR)
    • LH = Latent Heat (Change in State)
    • TH = Total Heat (SH + LH)
    • SHR = Sensible Heat Ratio
    • SHF = Sensible Heat Factor (Same as SHR)
    • h = Enthalpy (BTU’s/Lb of Air)
    • DB = Dry Bulb Temperature
    • WB = Wet Bulb Temperature
    • OA = Outside Air
    • RA = Return Air
    • MA = Mixed Air
    • Hr = Humidity Ratio = Grains of Water/Lb of Dry Air
    • gr = Grains of Water/Lb of Dry Air = Humidity Ratio
    • DP = Dew Point (Temperature at Which Air Condenses)
    • Cp = Specific Heat = BTU’s/Lb > (1) Degree F
    • RD = Relative Density
    • Saturation = When DP = DB = WB (100% RH)
    • PB = Barometric Pressure in In HG
  • Psychometric Chart
    • SHR Index = 78 DB/65 WB (50% RH) Room Condition
    • SHR Line = Line intersecting SHR Index & SHR value on the
    • SHR index scale
    • Coil Lines = From the mixed condition follow the coil line to the
    • SHR line to determine coil LAT (DB & WB)
    • Delta h = (Mixed Air h = Coil Leaving h)
  • Heat Transfer (Methods of)
    • Conduction = Heat Transfer by two bodies in contact
    • Convection = Heat Transfer by movement of fluid
    • Radiation = Heat Transfer by wave motion
  • Conduction
    • Q = Quantity = BTUH
    • A = Area
    • Delta T = Temperature Difference
    • U = U Value = 1/R
    • R = R Value = 1/U
    • U Total = Sum of U Values of Composite Material
  • Pressure
    • HG = Mercury Gauge
    • WG = Water Gauge
    • PSI = Lbs/Sq. In.

Conversion Factors

  • Efficiency
    • COP = Cooling Effect/Energy Input
    • Combustion Eff = (Input – Stack Loss)/Input
    • Energy Eff = Output/Input
  • Conduction
    • Q = U x A x Delta T
  • Pressure
    • 1 PSI = 2.31 Ft Head
    • 1 PSI = 27.7 In WG
    • 1 PSI = 2.04 In HG (Mercury)
    • 1 Ft Hd = .433 PSI
    • 1 Ft Hd = 12.0 In WG
    • 1 Ft Hd = .883 In HG
    • 1” WG = .036 PSI
    • 1” WG = .083 Ft Hd
    • 1” HG = 13.6 In WG
    • 1” HG = 1.13 Ft Hd
    • 1 Atmosphere = 29.92 In HG
    • 1 Atmosphere = 14.696 PSI
  • Water
    • Water = 8.33 Lbs/Gal
    • Cu.Ft. = 7.48 Gal
    • Lb = 7,000 Grains
    • BTUH = GPM x 500 x Delta T
    • Temp Mix = ((Gpm 1 x T 1)x(GPM 2 x T 2))/(GPM 1 + GPM 2)
    • TDH = (Pd – VPd)-((Pi(static)-VPi)
    • GPM = BTUH/500/Delta T
    • GPM = BTUH/(500 x Delta T)
    • Delta T = BTUH/500/GPM
    • 970 BTU’s/# = Heat of Vaporization of 212 F Water
    • 970 BTU’s/# = Heat Rejection of Evaporation
    • Cp = 1.00 BTU’s/Lb > (1) Degree F @ 68 F
    • Sp.Gr. = 1.00
    • Delta P = (GPM/CV)^2 – in PSI
    • GPM = CV x SQRT Delta P (in PSI)
  • Air
    • Std Air = 14.7 PSI (29.92” HG) @ .075 Lb/Cu Ft @ 70 F
    • D = 1/ Specific Volume = .075 #/Cu Ft (Std Air)
    • D = 1.322 x (PB/(Degree F + 460))
    • v = 1/Density = 13.333 Cu Ft/Lb (Std Air)
    • D @ Alt = -2%/1000’ Altitude (Correction Factor)
    • TH = SH + LH
    • TH = Delta h x 4.5 x CFM (Std Air)
    • LH = .67 x CFM x Hr
    • SHR = SH/TH
    • h = BTU’s/#/Hr
    • BTUH = CFM x Delta T x 1.085 (Std Air)
    • BTUH = (CFM x Delta T x 1.085)/.075 x D (Non-Std Air)
    • BTUH = 60 x Cp x D x CFM x Delta T
    • MA DB = T 1 + T 2
      • % OA x T DB = T 1
      • % RA x T DB = T 2
    • MA WB = (Same as MA DB)
    • MA DB = ((CFM 1 x DB 1)x(CFM 2 x DB 2))/(CFM 1 + CFM 2)
    • MA WB = (Same as MA DB)
    • MA DB = MA – RA = RA Delta T, MA – OA = OA Delta T
      • RA Delta T + OA Delta T = Total Delta T
      • % RA of Total + % OA of Total = Total Delta T
    • CFM = BTUH/1.085/Delta T
    • CFM = TH/4.5/Delta h
    • CFM = V x A
    • Delta T = BTUH/1.085/CFM
    • Cp = .24 BTU’s/Lb > (1) Degree F
  • Temperature
    • F = (1.8 C) + 32
    • C = (F-32)/1.8
    • K = C + 273
    • R = F + 460
  • Altitude

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  •  Electrical
    • 1 KW = 1000 W
    • 1 KW = 3,414 BTU’s
    • 1 W = 3.413 BTU’s
    • 1 HP = 745.7 W
    • 1.34 HP = 1 KW
    • 1 HP = 2,545 BTUH
    • P = I x E                                    Watts = Volts x Amps
    • I = E / R                                    Amps = Volts / Ohms
    • I = P / E                                    Amps = Watts / Volts
    • E = P / I                                    Volts = Watts / Amps
    • E = I x R                                    Volts = Amps x Ohms
    • R = E / I                                    Ohms = Volts / Amps
    • R = P / I^2                                    Ohms = Watts / Amps^2
    • PF 1 Phase = KW/(I x E)            Real Power/ Apparent Power
    • KVA = (I x E x 1.73)/1,000
    • PF 3 Phase = KW/KVA            Real Power/Apparent Power
    • CLFA = (I rated/I actual) x FLA rated
    • BHP = (E x I x ME x Pf x 1.73)/746            – 3 Phase
    • BHP = (E x I x ME x Pf)/746            – 1 Phase
    • BHP = HPr x ((MOA – (NLA x .5))/(CLFA – NLA x .5)))
  • (HPr = Rated Horsepower)

Fan Laws        

  • CFM 2/CFM 1 = RPM 2/RPM 1
  • SP 2/SP 1 = (RPM 2/RPM 1)^2 = (CFM 2/CFM 1)^2
  • BHP 2/BHP 1 = (RPM 2/RPM 1)^3 = (CFM 2/CFM 1)^3
  • D 2/D 1 = (RPM 2/RPM 1)^2
  • RPM 2 = RPM 1 x (CFM 2/CFM 1)
  • CFM 2 = CFM 1 x (RPM 2/RPM 1)
  • DIA 2 = DIA 1 x (RPM 2/RPM 1)                        DIA = Diameter
  • RPM 2 = RPM 1 x (DIA 2/DIA 1)
  • SP 2 = SP 1 x (RPM 2/RPM 1)^2
  • SP 2 = SP 1 x (CFM 2/CFM 1)^2
  • D 2 = D 1 x (RPM 2/RPM 1) ^2                        D = Density
  • BHP 2 = BHP 1 x (CFM 2/CFM 1)^3
  • BHP 2 = BHP 1 x (RPM 2/RPM 1)^3
  • CFM 2 = CFM 1 x SQRT (SP 2/SP 1)
  • RPM 2 = RPM 1 x SQRT (D 2/ D 1)

Corrections for Density (Altitude) from Catalog Data

  • CFM 2 = CFM 2 (Quantity is Constant)
  • BHP 2 = BHP 1/Relative Density
  • SP 2 = SP 1/Relative Density

Fan Application Formulas

  • TP = SP + VP
  • VP = (V/4005)^2
  • VP = (CFM/(A x 4,005))^2
  • V = 4,005 x SQRT(VP)
  • V = 1,096 x SQRT(VP/D)
  • BHP = (CFM x SP)/(6,356 x Fan Eff) Swags             (AF=75% BI=70% FC=65%)
  • BHP = (CFM x TP)/(6356 x Eff T)
  • BHP = (CFM x SP)/(6356 x Eff S)
  • I = (HP x 746)/(E x Eff x Pf x 1.73)            -3 Phase
  • I = (HP x 746)/(E x Eff x Pf)                        -1 Phase
  • TP Loss = C x VP
  • V = Vm x (D/.075)                        Vm = Velocity Measured, D = Density (Non-std)
  • TS = ((DIA x 3.1416)/12)*RPM

Sheave Calculations

  • DIA n = DIA o x (RPM n/RPM o)                        n = New, o = Old
  • DIA m = (RPM f x DIA f)/RPM m                        f = Fan, m = motor
  • DIA f = (RPM m x DIA ms)/RPM f

Equivalent Round Size of Rectangular Duct

  • De = 1.30(((ab)^.652)/((a + b)^.250))
    • De = Diameter Equivalent
    • a = One side of duct
    • b = Adj side of duct

Velocities/ Velocity Pressures

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Pump Laws

  • GPM 2/GPM 1 = RPM 2/RPM 1 = (DIA 2/DIA 1)
  • P 2/P1 = (RPM 2/RPM 1)^2 = (DIA 2/DIA 1)^2 = (GPM 2/GPM 1)^2
  • BHP 2/BHP 1 = (RPM 2/RPM 1)^3 = (DIA 2/DIA 1)^3 = (GPM 2/GPM 1)^3
  • RPM 2 = RPM 1 x (GPM 2/GPM 1)
  • GPM 2 = GPM 1 x (RPM 2/RPM 1)
  • GPM 2 = GPM 1 x (DIA 2/DIA 1)
  • DIA 2 = DIA 1 x (RPM 2/RPM 1)
  • DIA 2 = DIA 1 x (GPM 2/GPM 1)
  • RPM 2 = RPM 1 x (DIA 2/DIA 1)
  • P 2 = P 1 x (GPM 2/GPM 1)^2
  • P 2 = P 1 x (RPM 2/RPM 1)^2
  • P 2 = P 1 x (DIA 2/DIA 1)^2
  • BHP 2 = BHP 1 x (GPM 2/GPM 1)^3
  • BHP 2 = BHP 1 x (RPM 2/RPM 1)^3
  • GPM 2 = GPM 1 x SQRT (P 2/P 1)

Pump Application Formulas

  • BHP = (GPM x THD)/(3,960 x Eff)
  • WHP = (GPM x H x 1.00)/3960
  • Eff = (WHP x 100)/BHP in %
  • BHP = WHP/Eff

Fan Types

  • FC =             Forward Curve, typical Eff 50%, can easily overload
  • Hump at left of curve is region of instability
  • BI =             Backward Incline, typical Eff 60%, non-overloading
  • AF =             Airfoil Blade, typical Eff 70%, non=overloading
  • Similar performance to BI but more Eff and quiter
  • Exceeding 75% Eff on BI or AF will usually put fan in surge

Pump Curves

  • Series = GPM remains constant and Ft Hd is additive
  • With (1)pump operational Ft Hd drops & GPM remains constant
  • Parallel = Ft Hd remains constant and GPM is additive
  • With (1)pump operational Ft Hd & GPM drop but GPM can
  • exceed single pump selection BHP
  • No-Flow = Dead head of pump, Disch PSIG – Suction PSIG = PSIG on                                                             curve
  • Full-Flow =Disch PSIG – Suction PSIG = PSIG on curve

Piping System

  • Series = All water sees all load
  • Direct = Pressure drop across load varies
  • Reverse = Pressure drop across load is equal (S & R)

TAB Instruments

  • Airflow Instruments
    • U-Tube Manometer: Measure pressure above 1.00” WG
    • Inclined Manometer: Measure pressure above .02” WG
    • Micro-Manometer: Measure very low pressures (V or S)
    • Pitot Tube: Used with manometer
    • Magnehelic: Measure Static Pressure
    • Rotating Vane: Measure velocity
    • Thermal Anemometer: Measure low velocity
    • Flow Hood: Measure CFM directly
  • Hydronic Instruments
    • U-Tube Manometer: Measure pressure drops
    • Gauge, Calibrated: Measure static pressure
    • Gauge Differential: Measure differential pressure
    • Flow Devices: Measure flow by pressure differential
    • Venturi Tube: Fixed tube area
    • Orifice Plate: Fixed plate opening area
    • Annubar: Flow sensing tube
    • Balance Valve (Cal): Comb venturi & balance valve
  • Rotation Instruments
    • Revolution Counter: Contact measurement of revolutions
    • Chronometric Tach: Contact measurement with clock
    • Optical Tach: Non-Contact measurement reflective
    • Stroboscope: Non-Contact measurement sequence
  • Temperature Instruments
    • Glass Tube: Measuring air or water
    • Dial: Measuring air or water
    • Thermocouple: Measuring surface temperature
    • Electronic: Measuring air or water
    • Psychrometers: Measuring wet bulb/dry bulb
    • Thermo-Hygrometer: Measuring wet bulb/dry bulb & RH

Proportional (Ratio) Balancing

  1. Select the branch or terminal farthest from the supply fan
  2. Measure airflow of each outlet (Q)
  3. Calculate the percentage of design (X%) for each outlet
    1. Qm/Qd = X%
  4. Organize data as follows

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5. Outlet 6 is not adjusted

6. Adjust outlet 4 to approx 155 CFM and recheck 6 which should be at 155 CFM

7. Adjust outlet 3 to approx 160 CFM and 6 & 4 should follow

8. Continue until complete and recheck all

Pitot Traverse

Minimum Retangular Duct Traverse

 

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Minimum Round Duct Traverse

  • 6 – 10 point traverse in each horizontal & vertical axis
  • 6 points for 3” – 9” Dia
  • 8 points for 10” – 12” Dia
  • 10 points for 14” – 36” Dia
  • Calculate velocity from each VP reading, average to obtain average velocity forboth rectangular and round traverse.

Sound Pressure Chart

Greenheck eCAPs online Fan Application Suite: http://www.greenheck.com/content/view/software_ecaps?ref=software

Greenheck Psychrometric Chart: http://www.greenheck.com/content/view/software_psychrometric?ref=software Argentina