# A+ Answers

**PF 286099**

6. A double-acting cylinder with a 3.0-inch bore operates at 75 psig. It has a stroke of 12

inches and completes 10 complete extend-and-retract strokes per minute. What is the

required airflow to this cylinder? You can ignore the rod diameter for the retract stroke.

9. A volume of 7.5 ft of air is compressed to 2.2 ft. The compression ratio is

**A. **4.1. **C. **3.4.

**B. **2.2. **D. **0.29.

11. A pneumatic pipe that’s 60 feet long should have a slope with a drop of about _______

inches from one end to the other.

**A. **1.2 **C. **7.5

**B. **6.0**D. **18.0

12. If allowable motor duty cycle is 80%, what size compressor in SCFM is required to supply

a pneumatic system that consumes 60 CFM at 75 psig?

**A. **516**C. **814

**B. **542**D. **458

13. Approximately what motor Hp will be required for a two-stage compressor for a 250 SCFM

pneumatic system that operates at 100 psig?

**A. **44.75 **C. **25.0

**B. **41.0 **D. **100

16. What is the force required from an actuator to move a 28-pound bracket across a metal

table if the coefficient of sliding friction is 0.28?

**A. **5.6 lb**C. **28 lb

**B. **7.8 lb**D. **100 lb

**B. **7.8 lb**D. **100 lb

17. A pneumatic cylinder must lift a 14-pound weight a distance of 6 inches. The inertial load

is calculated to be 10.5 pounds. What approximate minimum force should be specified for

the cylinder in this application?

**A. **11 lb **C. **25 lb

**B. **15 lb **D. **50 lb

18. What would be the minimum bore size for a cylinder if it needed to develop 550 pounds of

force and operate from a pressure of 110 psig?

**A. **2.52 in **C. **2.98 in

**B. **2.75 in **D. **3.15 in

19. What torque is produced by a 2.5 Hp air motor that operates at 1800 rpm with 80 psig air

pressure?

**A. **9.0 lb-in**C. **87.5 lb-in

**B. **32 .0 lb-in **D. **720 lb-in

**PF 286098**

1. Two hundred cubic feet of air at 14.7 psia is compressed to 90

psig. What volume of receiver is required?

**A.**28.1 ft

**B.**32.7 ft

**C. **39.0 ft

**D. **41.3 ft

2. A pressure of 87 psig is measured on the inlet side of a pneumatic line filter, and a pressure of 83 psig is measured on the outlet side of the filter.

Which of the following is correct?

**A.**This is an example of static pressure, and no gas is flowing.

**B.**This is an example of a pressure drop, and gas is flowing through the filter.

**C.**The pressure should increase across the filter which therefore must need to be cleaned or replaced.

**D. **The filter isn’t working correctly; no pressure drop should be present at any time.

5. Which of the following statements is true?

**A.**Atmospheric pressure is about 29.4 psig.

**B.**101 kPa is about 10.1 psi.

**C.**30 psia is the same as 15.3 psig.

**D. **2.1 MPa is the same pressure as 21 kPa.

6. A closed receiver of compressed air has a volume of 10 cubic feet and a pressure of 90

psig. A valve is open that then connects an additional 5 cubic feet of volume due to the

piping and tubing from the system. What will the new gauge pressure be?

**A.**45 psig **C. **69 psig

**B.**55 psig **D. **180 psig

11. Two thousand cubic feet of gas that’s compressed from a free pressure of 14.7 psia to a

working pressure of 90 psig

**A.**will have a much greater volume.

**B.**won’t have much energy stored in its volume.

**C.**requires special compressors to reach the desired pressure.

**D. **will likely have its temperature raised significantly as it’s compressed.

12. In a closed pneumatic system (maintaining a constant volume), you know from the general

gas law that if you decrease the

**A.**volume, the temperature will remain the same.

**B.**temperature of the gas, the pressure will increase.

**C.**pressure, the temperature will increase.

**D. **pressure, the temperature will decrease.

15. A cylinder has a 3.0-inch bore and a 0.75-inch diameter rod extending from both sides of

the piston. If the cylinder is pressurized by 100 psig air so that the rod is extended, what

force is developed by the cylinder?

**A.**100 lbs.**C. **663 lbs.

**B.**300 lbs.**D. **707 lbs.

16. Air is flowing through an intake line to a compressor. If the inside diameter of the line is

2.5 inches and the air is moving at a velocity of 40 feet per second, what is the volumetric

flow in cubic feet per minute (CFM)?

**A.**0.114 CFM **C. **40 CFM

**B.**196.3 CFM **D. **81.8 CFM

17. A pipe must carry about 10 CFM of air at a maximum velocity of 25 feet per second. What

should the minimum pipe inside diameter be?

**A. **inches **C. **1.1 inches

**B.**1.0 inches **D. **1 Inches

18. Gas is put into a receiver at a temperature of 150°F and a pressure of 120 psia. After

being cooled to 60°F, what is the pressure of the gas in the receiver?

**A.**48 psia **C. **140.8 psia

**B.102.3 psia D. 300 psia**

**19. An air cylinder has a 4.0-inch bore and a 1.25-inch rod diameter. How much must the**

**pressurization on the retraction stroke be increased to maintain the same force for both**

**extending and retracting?**

**A.**10.8% **C. **22.4%

** **

**B.**12.5% **D. **68.8%