Thermo Units & Properties

Question 0

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

Answer 0

C. 1.5 psia 27”Hg x 0.491psi = 13.257psiv P(abs) = P(atm) – P(vac) 1”Hg

Question 1

An atmospheric pressure of 15 psia approximately equals… A. 30.0 psig. B. 29.4 psig. C. 14.7 psig. D. 0.0 psig.

Answer 1

D. 0.0 psig P(abs) = P(atm) + P(gauge)

Question 2

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

Answer 2

D. 12.5 psia 5”Hg x 0.491psi = 2.455psiv P(abs) = P(atm) – P(vac) 1”Hg

Question 3

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

Answer 3

C. 915 psia P(abs) = P(atm) + P(gauge)

Question 4

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

Answer 4

D. 20 inches of mercury (Hg) vacuum P(abs) = P(atm) – P(vac)

Question 5

Which one of the following is approximately equivalent to 2 psig? A. 11 psia B. 13 psia C. 15 psia D. 17 psia

Answer 5

D. 17 psia P(abs) = P(atm) + P(gauge)

Question 6

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

Answer 6

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

Question 7

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

Answer 7

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

Question 8

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

Answer 8

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

Question 9

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

Answer 9

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.

Question 10

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

Answer 10

D. 20 inches Hg absolute, 8 psia, 2 psig

Question 11

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

Answer 11

A. 2 psig, 20 inches Hg absolute, 8 psia

Question 12

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

Answer 12

D. 12 psia, 30 inches Hg absolute, 2 psig

Question 13

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

Answer 13

D. 14 inches Hg vacuum

Question 14

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

Answer 14

B. 2 psig, 18 inches Hg absolute, 8 psia