1) A six point pilot traverse of a 5" duct gave the following velocity pressures: 0.39, 0.40, 0.41, 0.42, 0.40, 0.38. What is the average air flow in cubic feet/min (cfm)? What is the Reynold's number?
2) A hood connected by a 14" diameter duct has a hood static pressure reading of -4"wg. V = 5000 fpm.
a. Calculate the coefficient of entry. Ce.
b. Calculate the hood entry loss, he.
c. Calculate the hood entry loss factor, Fd.
3) During the design of a ventilation system, a hood is calculated to have a hood static pressure (SPh) of -1.2"wg with an air flow (Q) of 1000 cfm. When the system is built and operated. SPh is measured and found to be -2.0"wg. If the hood coefficient of entry was chosen correctly during the design (design Ce = actual Ce), what is the actual flow through the system?
4) Static pressure is measured in a duct to be -3.1"wg. Total pressure is -2.4"wg. What is the velocity in the duct?
5) The hood static pressure is -3.0"wg and the average velocity in the 10" diameter duct downstream of the hood is 3500 fpm. What is the coefficient of entry, Ce, for this hood?
6) How many kilograms of ammonia are in a 3000 ft' tank when the gauge pressure is 950 psi and the ammonia temperature is 31oC?
7) A pressure vessel contained carbon monoxide compressed to 17 atmospheres at 43°F. The tank ruptures at what is believed to be an internal CO temperature of 300°F. People die from the blast effects and chemical asphyxiation. Accident reconstruction attempts to determine the probable internal pressure of the CO when the tank blew apart. What would you tell them?
8) What is the expected capture velocity 8" in front of a 2.5" x 3' flanged slot hood with a slot velocity of 2000 fpm?
9) An exhaust duct static pressure is 1.34"wg. The total system pressure is -0.63"wg. What are the standard air velocity pressure and the duct velocity?
10) What is the density of dry air at I 20°F?
11) A compressed gas cylinder contains hydrogen at 25°C and at a gauge pressure of 2000 prig. The cylinder's volume is 45 I (liters). What is the mass of hydrogen in this cylinder?
12) An exhaust system operates at 19,400 cfm. A hood is added to the system which requires a total system capacity of 23,700 cfm. By how much should fan speed be increased to handle the extra exhaust volume?
13) A ventilation system was designed to exhaust 17,500 cfm at a static pressure of 3.46"wg at the fan inlet. A static pressure reading at the fan inlet is 2.66"wg two years after the system was installed. What is the present exhaust volume?