Hydraulics and Pneumatics: Questions and Problems

Components of Pneumatic Systems

Question 1 

Which of the following is a component of a pneumatic system?

a.A compressor

b.An electric motor

c.An actuator

d.A valve

e.All of the above

Question 2

Which of the following is the purpose of a regenerative circuit?

A.To slow down the extending speed of a double-acting cylinder

B.To regulate the bulk modulus of the working fluid

C.To speed up the retracting velocity of a double-acting cylinder

D.To speed up the extending velocity of a single-acting cylinder

E.None of the above

Question 3

Which of the following is true about components of a pneumatic system such as valves, pipes, and compressors?

A.Undersized components such as pipes and valves does not influence pressure losses

B.Oversized components such as pipes and valves result in excessive initial installation costs

C.Air pressure loses in pipes does not influence the compressor required output pressure nor the input power.

D.Air leaks in pipe does not influence the flow rate required from the compressor

E.None of the above

Question 4

Conductors and fittings should not be made out of copper for what of the following reason: 

A.Copper is expensive

B.Copper is a poor conductor of heat 

C.Copper is a good conductor of electricity

D.Copper has lower modulus of elasticity

E.None of the above

Question 5

Which of the following statements is NOT true about s hydraulic distribution system?

A.The flow velocity on the discharge side of a pump is always greater than that on the suction side

B.Zinc, magnesium and molybdenum cannot be used conductors or fittings

C.Hydraulic pipes are classified by nominal size and schedule number

D.A thin wall cylinder has a ratio of the inside diameter to the thickness greater than 10

E.None of the above

Question 6

Which of the following is NOT one of the four criteria by which the size of a hydraulic reservoir is determined?

A.It must make allowance for dirt and chips to settle and air to escape

B.Its inner surface must be covered with a layer of stainless still to avoid corrosion

C.It must maintain oil level high enough to prevent a whirlpool effect at the pump inlet

D.It must have a surface area large enough to dissipate heat

E.All of the above

Question 7

Which of the following is the main advantage of the piston type accumulator over other gas type accumulators?

A.Its ability to handle very high or low temperature system fluids

B.Its small weight-to-volume ratio

C.A positive sealing between the gas and oil chambers

D.Its exclusive use of nitrogen

E.None of the above

Question 8

Which of the following is susceptible of making a pump noisy?

A.Air entering pump inlet.

B.Misalignment of pump and drive unit.

C.Excessive oil viscosity.

D.Dirty inlet strainer.

E.All of the above

Question 9

In hydraulic systems, why should hydraulic fluids operating temperatures be kept under 140oF?

A.To avoid deteriorating the viscosity

B.The avoid deteriorating the lubricity

C.To avoid water evaporation

D.Fluids can work above 140oF without adverse consequences 

E.None of the above 

Question 10 

Which of the following is NOT a basic type of filtering method used in hydraulic systems?

A.Mechanical

B.Photosynthesis 

C.Absorbent

D.Adsorbent

E.None of the above

Problem 1 

Two liters of SAE 30 oil weighs 17.4 N. Calculate the oil’s

a.Specific weight

b.Density

c.Specific gravity

Problem 2

A hydraulic cylinder has a 150 mm diameter. How much oil pressure P (kPa) is required to produce 5,000 N force at its piston?

Problem 3

An unloading valve is used to unload a 20-gpm pump. If the pump discharge pressure during unloading equals 30 psi, how much hydraulic horsepower is being wasted? 

Problem 4 

A pneumatic vacuum lift system has a total volume of 5 ft3 inside the cup and associated pipeline leading to the vacuum pump. The vacuum pump produces a flow rate of 4 scfm when turned on. The desired suction pressure is 5 psia and atmospheric pressure is 30 in Hg abs. Determine the time required to achieve the desired suction pressure.

Problem 5 

A pipe handles a flow rate of 15 gpm. Find the minimum inside diameter that will provide an average fluid velocity not the exceed 20 ft/s. 

Problem 6 

A steel tubing has a 1-in outside diameter and a 0.902-in inside diameter. It is made of AISI 1020 cold-drawn steel having a tensile strength of 75,000 psi. What would be the safe working pressure for this tube assuming a factor of safety of 8?