**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

- 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**

**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**

- Select the branch or terminal farthest from the supply fan
- Measure airflow of each outlet (Q)
- Calculate the percentage of design (X%) for each outlet
- Qm/Qd = X%

- Organize data as follows

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

**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.

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

Quick Links: