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Tuesday, October 2, 2012

My Conversions Study Guide

 For IT class we have to learn a LOT of different conversions in a relatively short amount of time. I'm posting the study guide I created here, so that I do not loose it.
 I hope it can help you out as well .
 **
Psig to Psia = Psig + 14.7
Psia to PSig = Psia - 14.7
**
.491 = density of 1 cu" Hg
**
29.921 "Hg = perfect vacuum
**
pressure = Height * density
**
Density = Weight / volume
**
absolute pressure = gauge + atmospheric
gauge + ( Barometer "Hg * .491 )
**
absolute pressure = (Barometer "Hg - Vacuum gauge "Hg) * .491
**
1 PSIG =
2.307 ' WC
27.68 " WC
2.036 "Hg
**
1 ' WC =
12" WC
.433 psig
15.133 psia
.8826 "Hg
**
1 "Hg =
13.6" WC
1.133 ' WC
.4912 psig
15.1912 psia
**
1 atmosphere =
33.96 ' WC
14.7 psig
1 psia
760 mm Hg
29.912 "Hg
**
1 Cu ' =
1728 Cu "
(H2o) 62.4 lbs
7.48 gal
**
1 Gal =
231 Cu "
8.33 lbs
**
H20 specific gravity = 1.0
**
Specific gravity = weight cu ' / 62.4
**
Rankine - Kelvin - Fahrenheit - Celsius
R to F = R + 460[*] ( 459.67 ) [*] book states this
K to C = K + 273[*] ( 274.15 ) [*] book states this
F to R = F - 460
C to F = C - 273
R to C = R - 492  / 1.8 ( or R - 492 * .555 )
K to F = K - 273 * 1.8 + 32
R to K = R - 492 / 1.8 + 273
K to R = K - 273 * 1.8 + 492
F to C = F - 32 / 1.8 ( or F - 32 * .555 )
C to F = C * 1.8 + 32
**
BTU = amount of heat to raise 1 LB water 1F
calorie = amount of heat to raise 1 gr water 1C
**
1 BTU = 252 calories
1 calorie = .00397 BTU
1 kilo calorie = 3.97 BTU
**
1 ton refrigeration ( 1 ton ice melted over 24 hours ) = 288,000 BTU or 12,000 BTU hour
**
Convert 1 LB ice @ 32F to water, requires 144 BTU latent heat
**
time response measured in time constants - up to 5
**
x = 0
y = 0
~time constant 1 = pressure rise total * .632 + original pressure
x = pressure rise total * .632
Y = X + original pressure
~ time constant 2 = X * .632 + y
X = X * .632
Y = Y + X
~ time constant 3 = X * .632 + y
X = X * .632
Y = Y + X
~ time constant 4 = X * .632 + y
X = X * .632
Y = Y + X
~ time constant 5 = X * .632 + y
[ note: this is in programming terms so I can understand it - it's more confusing in the book ]
**
span = subtracting lowest range value from highest range value.
conversion of signals = find span of input and output - find the percentage of the (current input value - low value) compared to the

input span. Use that percentage on the output span. Add the low value from the output range
IE:
Input = Temperature range 100F - 500F
Output = Pressure range 3 psig - 15 psig
Current temperature = 300F
Input range = 400
Output range 12 psig
--
current temperature - low range = 200F
200 / 400 = .50 ... .50 * 12 psig = 6 psig .... 6 psig + 3 psig = 9 psig output signal
**

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