Thermo Units & Properties Flashcards
A pressure gauge on a condenser reads 27 inches of mercury (Hg) vacuum. What is the absolute pressure corresponding to this vacuum? (Assume an atmospheric pressure of 15 psia.) A. 14.0 psia B. 13.5 psia C. 1.5 psia D. 1.0 psia
C. 1.5 psia 27”Hg x 0.491psi = 13.257psiv P(abs) = P(atm) – P(vac) 1”Hg
An atmospheric pressure of 15 psia approximately equals… A. 30.0 psig. B. 29.4 psig. C. 14.7 psig. D. 0.0 psig.
D. 0.0 psig P(abs) = P(atm) + P(gauge)
Assuming a standard atmospheric pressure of 15 psia, 5 inches of mercury (Hg) vacuum is equivalent to… A. 2.5 psia. B. 5.0 psia. C. 10.0 psia. D. 12.5 psia
D. 12.5 psia 5”Hg x 0.491psi = 2.455psiv P(abs) = P(atm) – P(vac) 1”Hg
If a main steam line pressure gauge reads 900 psig, what is the absolute pressure? A. 870 psia B. 885 psia C. 915 psia D. 930 psia
C. 915 psia P(abs) = P(atm) + P(gauge)
Which one of the following is equivalent to 5 psia? A. 20 psig B. 10 psig C. 10 inches of mercury (Hg) vacuum D. 20 inches of mercury (Hg) vacuum
D. 20 inches of mercury (Hg) vacuum P(abs) = P(atm) – P(vac)
Which one of the following is approximately equivalent to 2 psig? A. 11 psia B. 13 psia C. 15 psia D. 17 psia
D. 17 psia P(abs) = P(atm) + P(gauge)
Which one of the following is the approximate condenser vacuum when condenser pressure is 16 inches Hg absolute? A. 4 inches Hg vacuum B. 8 inches Hg vacuum C. 12 inches Hg vacuum D. 14 inches Hg vacuum
D. 14 inches Hg vacuum 16”Hg abs x (0.491psi) = 7.856 psia ( 1”Hg ) P(abs) = P(atm) – P(vac) 7.144 psiv x ( 1” Hg ) = 14.59” Hg vac 7.865 psia = 15 – psiv (0.491 psi) psiv = 15 – 7.856 psia psiv = 7.144 psiv
Which one of the following is sequenced from lowest pressure to highest pressure? A. 8 psia, 20 inches Hg absolute, 2 psig B. 8 psia, 2 psig, 20 inches Hg absolute C. 20 inches Hg absolute, 2 psig, 8 psia D. 20 inches Hg absolute, 8 psia, 2 psig
A. 8 psia, 20 inches Hg absolute, 2 psig P(abs) = P(atm) + P(gauge) y”Hg(abs) x 0.491psi/1”Hg(abs) = ypsia
Which one of the following is arranged from the highest pressure to the lowest pressure? A. 2 psig, 20 inches Hg absolute, 8 psia B. 2 psig, 8 psia, 20 inches Hg absolute C. 8 psia, 20 inches Hg absolute, 2 psig D. 8 psia, 2 psig, 20 inches Hg absolute
A. 2 psig, 20 inches Hg absolute, 8 psia P(abs) = P(atm) + P(gauge) y”Hg(abs) x 0.491psi/1”Hg(abs) = ypsia
A water storage tank is enclosed to prevent vapors from escaping to the environment. The tank is also pressurized with nitrogen to prevent air inleakage. A differential pressure detector with a dry reference leg is used to measure the tank level. To achieve the greatest accuracy of measurement, the low pressure side of the detector should sense which one of the following? A. The pressure at the bottom of the tank B. The pressure of the atmosphere surrounding the tank C. The pressure of a column of water external to the tank D. The pressure of the gas space at the top of the tank
D. The pressure of the gas space at the top of the tank - This would allow for a differential pressure and compensation for the vapor pressure.
Which one of the following is arranged from the lowest pressure to the highest pressure? A. 8 psia, 20 inches Hg absolute, 2 psig B. 8 psia, 2 psig, 20 inches Hg absolute C. 20 inches Hg absolute, 2 psig, 8 psia D. 20 inches Hg absolute, 8 psia, 2 psig
D. 20 inches Hg absolute, 8 psia, 2 psig
Which one of the following is arranged from the highest pressure to the lowest pressure? A. 2 psig, 20 inches Hg absolute, 8 psia B. 2 psig, 8 psia, 20 inches Hg absolute C. 8 psia, 20 inches Hg absolute, 2 psig D. 8 psia, 2 psig, 20 inches Hg absolute
A. 2 psig, 20 inches Hg absolute, 8 psia
Which one of the following is arranged from the lowest pressure to the highest pressure? A. 2 psig, 12 inches Hg absolute, 8 psia B. 2 psig, 18 inches Hg absolute, 8 psia C. 12 psia, 20 inches Hg absolute, 2 psig D. 12 psia, 30 inches Hg absolute, 2 psig
D. 12 psia, 30 inches Hg absolute, 2 psig
Which one of the following is the approximate condenser vacuum when condenser pressure is 16 inches Hg absolute? A. 4 inches Hg vacuum B. 8 inches Hg vacuum C. 12 inches Hg vacuum D. 14 inches Hg vacuum
D. 14 inches Hg vacuum
Which one of the following is arranged from the highest pressure to the lowest pressure? A. 2 psig, 12 inches Hg absolute, 8 psia B. 2 psig, 18 inches Hg absolute, 8 psia C. 12 psia, 20 inches Hg absolute, 2 psig D. 12 psia, 30 inches Hg absolute, 2 psig
B. 2 psig, 18 inches Hg absolute, 8 psia