10 Jan A pipe handles a flow rate of 35 gpm. Find the minimum inside diameter that will provide an average fluid velocity not the exceed 20 ft/s.

MET230: Hydraulics and Pneumatics

Week 4 Review Assignment

Problem 1

A pipe handles a flow rate of 35 gpm. Find the minimum inside diameter that will provide an average fluid velocity not the exceed 20 ft/s.

Problem 2

A steel tubing has a 1.5-in outside diameter and a 1.210-in inside diameter. It is made of AISI 1020 annealed steel having a tensile strength of 57,000 psi. What would be the safe working pressure for this tube assuming a factor of safety of 8?

Problem 3

Select the proper-sized steel tube for a flowrate of 25 gpm and an operating pressure of 1,000 psi. The maximum recommended velocity is 20 ft/s and the factor of safety 8. The tube is made out of SAE 1010 with a tensile strength of 55,000 psi.

Figure 10-7. Common tube sizes

Problem 4

Oil at 24 gpm and 1200 psi enters the low-pressure inlet of a 4:1 Racine pressure intensifier. Find the discharge flow rate and pressure.

Problem 5

Oil at 155oF and 2250 psi is flowing through a pressure relief valve at 25 gpm. What is the downstream oil temperature?

Note

· 1 hp = 42.4 Btu/min.

Also, for oil under consideration,

· Specific heat = 0.42 Btu/lb/oF

· 1 gpm = 7.42 lb/min

Problem 6

A hydraulic pump operates at 150 bars and delivers oil at 0.0015 m3/s to a hydraulic actuator. Oil discharges through the pressure relieve valve (PRV) during 50% of cycle time. The pump has an overall efficiency of 87%, and 15% of power is lost due to frictional pressure losses in the hydraulic lines. What heat –exchanger rating is required to dissipate all the generated heat?

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MET230: Hydraulics and Pneumatics

Week 4 Study Guide 1

Question 1

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

A. A primary purpose of a fluid distribution system is to carry the fluid from the reservoir through operating components and back to the reservoir

B. The flow velocity generally recommended for the discharge side of a pump is 25 ft/s

C. The flow velocity generally recommended for the inlet side of a pump is 4 ft/s

D. Conductors and fittings should not be made out of copper

E. None of the above

Answer B. “The flow velocity generally recommended for the discharge side of a pump is 25 ft/s”

Justification: The recommended velocity is 20 ft/s.

Question 2

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

A. Zinc, magnesium and cadmium cannot be used conductors or fittings

B. Malleable iron cannot be used for hydraulic fitting

C. Hydraulic shock raises the system pressure up to 4 times of the steady state value

D. Conductors should always have greater strength than the required system working pressure

E. None of the above

Answer: B. “Malleable iron cannot be used for hydraulic fitting”

Justification: Malleable iron can be used for hydraulic fittings for low-pressure lines such as inlet, return and drain lines.

Question 3

Which of the following metals CANNOT be used with water-glycol hydraulic fluids?

A. Zinc

B. Magnesium

C. Cadmium

D. A, B, and C

E. None of the above

Answer D. “A, B, and C”

Question 4

Which of the following variables determine the wall thickness and factor of safety of a conductor for a particular operating pressure?

A. Tensile strength of conductor material

B. Conductor outside diameter

C. Operating pressure levels

D. A, B, and C

E. None of the above

Answer D. “A, B, and C”

Question 5

Which of the following is NOT one of the four primary types of hydraulic conductors?

A. Steel pipe

B. Steel tubing

C. Plastic tubing

D. Flexible hose

E. None of the above

Answer: E. “None of the above”

Question 6

Which of the following is 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. It must hold all the oil that might drain form the system

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

Answer: E. “All of the above”

Question 7

Which of the following is NOT one of the three common reservoir design?

A. U-shaped design

B. Flat top design

C. L-shaped design

D. Overhead stack design

E. None of the above

Answer: A. “U-shaped design”

Question 8

Which of the following accumulators creates a constant fluid pressure throughout the full volume output of the unit regardless of the rate and quantity of output?

A. Weight loaded accumulator

B. Spring loaded accumulator

C. Gas loaded accumulator

D. No accumulator create a constant pressure

E. None of the above

Answer: A. “Weight loaded accumulator”

Question 9

Which of the following is NOT a major separator-type gas-loaded accumulators?

A. Piston accumulator

B. Diaphragm accumulator

C. Bladder accumulator

D. Gravity loaded accumulator

E. None of the above

Answer: D. “Gravity loaded accumulator”

Question 10

Which of the following is the main advantage of the bladder 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

Answer: C. “A positive sealing between the gas and oil chambers”

Question 11

Which of the following materials is used for hydraulic seals?

A. Leather

B. Buna-N

C. Silicone

D. Neoprene

E. All of the above

Answer E. “All of the above”

Question 12

Which of the following is one of important factors to consider when selecting a heat exchanger?

A. Heat generation rate

B. Oil flow rate

C. Allowable oil temperature

D. A, B, and C

E. None of the above

Answer D. “A, B, and C”

Question 13

Which of the following is a flow-measuring device?

A. Rotameter

B. Durometer

C. Bourdon gage.

D. Schrader gage

E. None of the above

Answer: A. “Rotameter”

Question 14

Which of the following is a pressure-measuring device?

A. Rotameter

B. Turbine flow meter.

C. Durometer

D. Schrader gage

E. None of the above

Answer: D. “Schrader gage”

Problem 1

A pipe handles a flow rate of 25 gpm. Find the minimum inside diameter that will provide an average fluid velocity not the exceed 20 ft/s.

( Hint: 1 ft3/s = 449 gpm)

Solution

Known Data

Pipe flow rate Q = 25 gpm = 0.05568 ft3/s

Maximum average velocity v = 20 ft/s

Unknown (s)

Minimum inside diameter D?

Needed

Pipe flow area A?

Formula (s)