A-6
AppendixAppendix
AppendixAppendix
Appendix Model 356WModel 356W
Model 356WModel 356W
Model 356WAA
AA
A
Teledyne Analytical Instruments
or by knowing the altitude
P(mm-Hg) = 760 - (2.50 per 100 ft. of altitude)*
The vapor pressure of water at ambient temperature can be obtained
from Table 1.
To determine the corrected flow (Fcorrected), substitute the ambient tem-
perature, pressure and vapor pressure of water in the following formula:
FT
294 K* *
760 mm Hg
P
PP
P
corrected ccmin water
=×
°
××
+
150
Where:T = ambient temperature (in °K)
P = ambient pressure (in mm Hg)
Pwater = vapor pressure of water at ambient temp. (in mm Hg)
By way of example, suppose that the target’s position on the flow tube
is in question and it has been determined that the ambient temperature is 77
°F and the altitude where the instrument is being used is 5000 ft. above sea
level.
*This approximation is within ±0.5% of the ICAO Standard Atmo-
sphere over the range 0-7500 ft. above sea level. Ref: “Fluid Mechanics for
Engineering Technology” by Irving Granet, Prentice Hall, pp 83–84.
** Reference ambient temperature : 294 °K (21 °C) was the ambient
temperature used in the Faradaic calculations.
()()Ambient Temp: K K
Ambient Pressure: P(mm Hg) = 760- 2.50 50 = 635 mm Hg
Vapor Pressure of Water (at 298 K): 23.9 mm Hg
Corrected Flow: F = 150 298
294
corr ccmin
°= − + = °
×
°
××× +
=
5
977 32 273 298
760
635
635 239
635 189
.