Equations Flashcards
Natural Gas Formula
1CH4+2o2+8N2=1Co2+2H20+8N2
Propane Gas formula
1C3H8+5o2+20N=3co2+4H2O+20N
lbs for CO2 Variables
117 NG and 135 Propane
LBS of C02 equation
(variable/1,000,000) x BTU input
% of C02
CO2/ total dry gases X100 (Don’t multiply by 100 if you do not want percent)
% of 02
02/ total dry gases X100 (Don’t multiply by 100 if you do not want percent)
What is the first equation for on the Gas formulae sheet
Q=CFM x 1.2 x deltaT
DFMUA for BTU
Steps for finding water produced
Divide BTU by CV (1000 or 2500)
Multiple by H20 produced (4 for propane 2 for NG)
divide by expansion ratio (1700)
Multiply by Us gal or Imperial Gas (7.48 US gal 6.24 Imperial Gal)
Absolute Zero
460 and 273
Atmospheric pressure
14.73 or 101.325
Second equation in Gas formulae sheet
Orifice flow (In gas code)
Q=flow
K factor
Area
delta P pressure drop across burners (Psi or “w.c)
SG- Specific gravity (.6 or 1.51)
(1psi is 27.08 inches water column)
How many Inches water column is 1 PSI
27.7
What is the variable change equation for orifice flow
Q2/Q1= K2/K1 X A2/A1 X square rootDeltaP2/DeltaP1 X squarerootSG1/SG2
Notice SG is flipped*
Expansion Of NG
600
Expansion of Propane
270
Expansion rate for steam to water
1700
How to transpose the orfice flow equation easily
Q divided by full equation = what your looking for
Third equation on list is for what
Clocking a meter
Q= Flow rate (Multiply but CV to get BTU)
t=rotation time in seconds
v-Dial size
PL- inlet pressure
PA- Sea level pressure
PS- Sea level pressure
TA 60 degrees
TS- Absolute
TA(bottom) Gas Temp
T- Absolute
Imperial gal
6.24
US Gal
7.48
Forth Equation on Gas formulae sheet
P1 X V1 / T1 = P2 X V2 / T 2 OR
P1 X T2 X V1 = P2 x T1 X V2
DFMUA Velocity equation
Velocity= T1 plus absolute / T2 plus absolute
muliplied by V2
Correction temp equation
60 plus absolute / wrong temp plus absolute
(460 or 273)
Correction pressure equation
wrong press + absolute / absolute
(14.73 or 101.325)
Fifth equation on gas formulae sheet
Velocity = 4005 X squareroot of deltaP
How many Oz in a pound
16
Sixth equation on the formula sheet
Theoretical Natural Draft
Ts- average stack temp plus absolute (460 or 273)
Ta- Ambient temp plus absolute
H Height of chimney
Excess air dry reading equation
0.895 X %A / 0.21 - %A
Excess air wet reading equation
1.105 x %B / 0.21 - %B
Seventh Equation on gas formulae sheet
Velocity= Volume / area
Latent heat of water to ice
144
Latent heat of water to steam
970.4
Calculating a state change from water to ice
144 X weight
Calculating a state change from water to steam
970.4 X weight
Eighth equation on gas formulae sheet
Area = Diameter squared X 0.7854
Or D= squareroot of area / 0.7854
Turn down ratio calculation
high fire / low fire
or max temp - min temp
divied by min rise
Calculation temperature change in water/ice/steam
specific heat X weight in lbs X DeltaT
Specific Gravity of NG
0.6
Specific gravity of Propane Vapour
1.51
Specific gravity of Propane Liquid
1.51
Calculation Net stack
Stack temp minus ambient temp
Flow increase on Diameter change
D2 ^2.623 divided by D1 ^2.623
Multiple by 100 for a percentage
Purge opening equation
square root D2/60
Cannot be less than 1/2”
Purge Time
Length of pipe/200 X2(safety factor)
Volume of pipe for purge calculation
Vol= (D/12)squared X .7854 X length
Second page #1 equation on Gas formula sheet
Flow equation/Pipe sizing
Q-Flow (multiple by CV for BTU)
D-Diameter
P1- (Service pressure plus absolute) Squared
P2- (Pressure at end of pipe plus absolute)Squared
L-Length
How many cubic feet are in a pressure cyclinder
226
Size of the cyclinder
1.5
Normal flue temp
350-500
Normal stack Velocity
.02-.16
Third equation on Page 2 gas formulae sheet
LBS CO2
Variables 117 NG 135 Propane
Converting square inches to square feet
Multiple by 144
Forth equation on 2nd Page
Air free CO PPM
Voltage triangle
E
I R
E-Volts
I-Amps
R-ohms
Watts Triangle
P
E I
P-watts
E-Voltage
I-Ohms
fifth equation on Page 2
PPm Nox
Sixth equation on Page 2
Fuel Loss
Ts- Fuel temp in C
Ta Supply air temp
Efficiency is 100 minus answer
How to convert Miliamps to Amps
Divide by 1000
Normal Hz of a motor
60 Hz
Seventh equation on page 2
Motor speed
Poles and RPMS
2-3600
4-1800
6-1200
8-900
Ninth equation on page 2
Slip
Ns- RPM
NR-Rotar speed on motor
Tenth Equation on Page 2
Torque
PhP- Horse power
n-RPM
Page 3 1st equation
Torque in metric
Pkw- Kilowatts
n-RPM
Page 3 second equation
Star circuit
phase volt divide by coil is amps
ephase X squareroot of3
Page 3 3rd equation
Wye circuit
Phase voltage / Coil amps is amps
Line voltage / squareroot of 3 is volts
Page 3 4th equation
Stunt resistance
How to get BHP to BTU
multiple by 33475
1 BHP is
34.5 LBS of 212 water or steam X LHV 970.4
How many btu of 1 foot of 215 steam
240
Hot many BTU is 1 foot of 170 water
150
How much is pipe loss in an EDR
33%
How to calculate gross EDR
Rad EDR multiply by piping
What is net EDR
Just the Rad without the piping
Equation for Wobbe
High heat Volume of gas divided by the squareroot of specific gravity
How many air changed for a purge
4
How much air has to be moving
60% of high fire
How to calculate vol of container for purge time
(Diameter/12”)squared X .7854 X length(Minus insinuation)
Water Vol- lbs of water capacity / 62.4
Take body vol and minus water vol
How to calculate Time for purge time
Fuel burners X 10ft X 1.2 (excess air)
Divided by 3600 to get to sec
Take vol of body(Multiply theby 4) and divide by fuel found in seconds
divide by 60 %
How to calculate available stack draft
theoretical draft X .80
Calculating volume of flue gases going up chimney
First take BTU / CV
Multiply that by your air needed and excess air then add gas back in
Put variables in the t2 x v2 = t1 x t2 to get your volume than change volume in per min (Divide by 60)
t2 x v2 = t1 x t2
T1-ambient temp plus absolute
T2-Stack temp plus absolute
V1-fuel + combustion air + excess air
Make stack size into area (Stack size/12) sqaured X 0.7854
Vel= volume/area = Answer
Equation to find deltaP using Velocity
DeltaP= (Velocity/4005) squared
Steps for calculating Full Load RPM change
Use RPM equation with new HZ
Use Slip equation with Old RPM
Take the new RPM multiple by slip rating (Decimal)
Take the new RPM and subtract the answer in step 3
Expansion tank sizing
Coefficient of vol multiply by
Volume of system Multiplied by
Change in liquid temp
Liquid gas into btu
Liquid divide by gal x 270 expansion x c.v
Mixed fuel new flow
Q2 = q1(org) squareroot sg1(org)/sg2 (mix)
Multiply by new c.v for btu
Calculating new sg and cv with propane mix air and fuel
Take new gas % and multiply by c.v= new cv valve
Take gas % and multiply by sg
Take air % and multiply by one. Add the last two steps together and is your new sg