Thermodynamic Units and Properties Flashcards
An atmospheric pressure of 15.0 psia is equivalent to…
0.0 psig.
A pressure gauge on a condenser reads 27.0 inches Hg vacuum. What is the absolute pressure
corresponding to this vacuum? (Assume a standard atmospheric pressure of 15.0 psia.)
1.5 psia
Assuming a standard atmospheric pressure of 15.0 psia, 5.0 inches Hg vacuum is equivalent to..
12.5 psia.
If a main steam line pressure gauge reads 900 psig, what is the absolute pressure?
915 psia
Which one of the following is equivalent to 5 psia?
20 inches of mercury (Hg) vacuum
Which one of the following is arranged from the lowest pressure to the highest pressure?
8 psia, 20 inches Hg absolute, 2 psig
Which one of the following is arranged from the highest pressure to the lowest pressure?
2 psig, 20 inches Hg absolute, 8 psia
Which one of the following is approximately equivalent to 2 psig?
17 psia
Which one of the following is arranged from the lowest pressure to the highest pressure?
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?
14 inches Hg vacuum
Which one of the following is arranged from the highest pressure to the lowest pressure?
2 psig, 18 inches Hg absolute, 8 psia
The tanks are identical and are being maintained at the same constant water level with 17 psia gas
pressure above the water. The tanks are surrounded by standard atmospheric pressure. The
temperature of the water in the tanks and reference legs is 70°F.
Which one of the level detectors is sensing the greatest D/P?
No. 2
A closed water storage tank is pressurized with nitrogen to prevent air inleakage. Tank pressure is
allowed to vary as water level changes. A differential pressure detector is used to measure the tank
level.
To achieve the most accurate level measurement, the low pressure side of the detector should sense
which one of the following?
The pressure of the gas space at the top of the tank.
The tanks are identical and are being maintained at 17 psia and 70 percent water level (calibration
conditions). They are located in a building that is currently at atmospheric pressure.
If the building ventilation system creates a vacuum in the building, which level detectors will provide
the lowest level indications?
1 and 4
The tanks are identical and are being maintained at 2 psig overpressure, the same constant water level,
and a temperature of 60°F. They are surrounded by atmospheric pressure.
If a leak in the top of each tank causes a complete loss of overpressure, which detector(s) will produce
a lower level indication?
No. 2 and 3
The tanks are identical and are being maintained at 2 psig overpressure, 60°F, and the same constant
water level. The tanks are located within a sealed containment structure that is being maintained at
standard atmospheric pressure. All level detectors have been calibrated and are producing the same
level indication.
If a ventilation malfunction causes the containment structure pressure to decrease to 13 psia, which
detectors will produce the lowest level indications?
1 and 4
The tanks are identical and are being maintained at 2 psig overpressure, 60°F, and the same constant
water level. The tanks are located within a sealed containment structure that is being maintained at
standard atmospheric pressure. All level detectors have been calibrated and are producing the same
level indication.
If a ventilation malfunction causes the containment structure pressure to decrease to 13 psia, which
detectors will produce the highest level indications?
2 and 3
The manometer is installed across an orifice in a ventilation duct to determine the direction of airflow.
With the manometer conditions as shown, the pressure at P1 is __________ than P2; and the direction
of airflow is __________.
greater; left to right
The tanks are identical with equal water levels and 20 psia gas pressure above the water. The tanks
are surrounded by standard atmospheric pressure. The temperature of the water in the tanks and
reference legs is 70°F.
If each detector experiences a ruptured diaphragm, which detector(s) will produce a reduced level
indication? (Assume that actual tank and reference leg water levels do not change.)
No. 2, 3, and 4
The manometer is installed across an orifice in a ventilation duct to determine the direction of airflow.
With the manometer conditions as shown, the pressure at P1 is __________ than P2; and the direction
of airflow is __________.
less; right to lef
A water storage tank is vented to atmosphere. The tank is located at sea level and contains 100,000
gallons of 80°F water. A pressure gauge at the bottom of the tank reads 5.6 psig. What is the
approximate water level in the tank?
13 feet
If the tank contains 30 feet of water at 60°F, what is the approximate D/P sensed by the detector?
13 psid
A water storage tank is vented to atmosphere. The tank is located at sea level and contains 100,000
gallons of water at 80°F. A pressure gauge at the bottom of the tank reads 7.3 psig. What is the
approximate water level in the tank?
17 feet
A water storage tank is vented to atmosphere. The tank is located at sea level and contains 100,000
gallons of water at 80°F. A pressure gauge at the bottom of the tank reads 9.0 psig. What is the
approximate water level in the tank?
21 feet
The tanks are identical and are being maintained at 2 psig overpressure, the same constant water level,
and a temperature of 60°F. The tanks are surrounded by atmospheric pressure. All level detectors
have been calibrated and are producing the same level indication.
If a leak in the top of each tank causes a complete loss of overpressure in both tanks, which detector(s)
will produce the highest level indication(s)?
No. 1 and 4
Refer to the drawing of an open water storage tank with a differential pressure (D/P) level indicator
that is vented to atmosphere (see figure below). Both the tank and the level indicator are surrounded
by standard atmospheric pressure. Tank water temperature is 70°F.
The D/P level indicator is sensing a differential pressure of 4.0 psi. What is the water level in the tank
above the instrument penetration?
9.2 feet
