Fluid Conductors

Question 0

What is the most important characteristic of “fluid Conductors”?

Answer 0

Efficiency is the most important characteristic of fluid conductors.

Question 1

What does the term “fluid conductors” mean in relation to a hydraulic system?

Answer 1

The tubing or piping and fittings used to connect the various hydraulic system units.

Question 2

For maximum efficiency, “fluid conductors” should have what two characteristics?

Answer 2

In order to assure maximum efficiency, the fluid conductors should be clean, leak-proof, and have streamlined flow.

Question 3

Name four factors that may cause turbulent flow in “fluid conductors”.

Answer 3

These include the velocity of the hydraulic system, friction, internal obstructions, and sharp turns in the fluid line.

Question 4

Name three negative results of turbulent flow.

Answer 4

Excessive Pressure Drop
Increased Power Consumption
Increased Oil Temperature

Question 5

What is the preferred “fluid conductor” material?

Answer 5

The most preferred material for lubricant conductors is SAE 1010 stainless steel tubing.

Question 6

Where are flexible lines necessary?

Answer 6

It is needed where units must be free to move relative to each other.

Question 7

What is flexible hose normally made of?

Answer 7

Stainless steel wire over reinforced synthetic rubber tube and covered by synthetic rubber.

Question 8

Name the three grades of flexible hose.

Answer 8

The three flexible hose grades are : low pressure, medium pressure, and high pressure.

Question 9

Name five precautions to follow when using flexible hose.

Answer 9

1. Do not twist or place the hose in axial torsion.
2. Bend the hose in one plane only.
3. Use the proper fittings and adapters to relieve excessive strain.
4. Provide sufficient slack to compensate for changes in length and working conditions.
5. Avoid any sharp and/or excessive bends.
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Question 10

Name four types of fittings used in industrial hydraulic systems.

Answer 10

1. Flared tube fitting
2. Flareless tube fitting
3. Socket welded fitting
4. Screwed fitting

Question 11

How much straight length of tube must be allowed from the end of the tube to the start of the bend when installing hydraulic tubing?

Answer 11

twice the length of the fitting nut

Question 12

Name four possible problems that can be avoided by the use of tube bending equipment.

Answer 12

kinks, flattened bends, wrinkles, and breakage

Question 13

Why is it important to use as few fittings as possible?

Answer 13

I saves money, reduces installation time, reduces hydraulic shock load, while minimizing the possible leak sites.

Question 14

What can be done to reduce the possibility of tubing fatigue?

Answer 14

Tubing fatigue can be reduced:

1. Support long tubing runs with brackets or clips
2. Bolt down all parts installed on tube lines, (i.e. heavy fittings, valves, etc.)

Question 15

Name five methods of cleaning pipes, tubes and fittings prior to assembly of a hydraulic system.

Answer 15

1. Use boiler tube wire brush
2. Use commercial pipe cleaning apparatus
3. Ream inside edges of tubing & pipe after cutting to remove burrs
4. Sandblast short pieces of pipe and fittings
5. Pickle long pieces of pipe, or pipe with complex bends

Question 16

When filling a hydraulic system with hydraulic fluid, what mesh screen is recommended?

Answer 16

120 mesh screen (120 squares per inch)

Question 17

How can air in hydraulic lines be eliminated?

Answer 17

Cycle the system while it is not under load. Bleed air until no bubbles are apparent. Keep system properly vented. Gradually bring the system up to temperature to slowly release dissolved air. Check for sources of air ingression. Eliminate contaminants that may affect air release.

Question 18

What type of chemical is used in pickling?

Answer 18

An inhibited acid solution

Question 19

What must be done to stop the pickling process?

Answer 19

Rinse the parts in cold running water and neutralize the pickling acid

Question 20

When the pickling process is completed, what is the next step?

Answer 20

Protect the pickled parts from rust.

Question 21

Why does the burst pressure of a Schedule 40 pipe decrease as the ID increases?

Answer 21

OD (outside diameter) stays constant

Wall thickness decreases

Question 22

What are three primary advantages of tubing over piping?

Answer 22

Less connections and leaks Lower pressure loss
High Pressure Lower cost
Neater Installations
Can bend tubing
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Question 23

What three ways are there for conveying hydraulic fluid?

List three types of fluid conductors.

Answer 23

1. piping
2. tubing
3. hose
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Question 24

A properly designed piping system will have feed lines operating at _______ to _______ FPS, return lines at ______ to ______ FPS, and suction lines to the pump at ______ to ______ FPS.

Answer 24

feed lines 5 to 7 FPS return lines 1to 3 FPS pump lines 3 to 5 FPS

Question 25

Piping selection is based on ___________, which is measured in FPS.

Answer 25

Flow velocity

Question 26

Piping must be large enough to prevent ________ in the pump suction lines.

Answer 26

Cavitation

Question 27

Would you increase or decrease the velocity of a hydraulic fluid to reduce turbulent flow?

Answer 27

In order to decrease turbulence, decrease the velocity of the fluid.

Question 28

How can the number of fittings be reduced?

Answer 28

By utilizing bends in tubing where practical.

Question 29

When measuring pipe, regardless of schedule number, what dimension of the pipe is consistent?

Answer 29

The OD (outer diameter)

Question 30

What are three advantages of hoses over rigid pipe?

Answer 30

Easy to install Not prone to Vibration Stress Utilized when machinery in motion

Question 31

Does 200-mesh screen have larger or smaller openings than 100 mesh?

Answer 31

200 is smaller – Twice as many openings. (NOTE: 100 mesh = Approx. 150 microns)

Question 32

Name four types of reclassifier nozzles for an air mist system.

Answer 32

Mist – Enclosed high speed application Spray – Larger Droplets for rolling elements Condensing – Droplets for sliding/plain bearings Pressure Jet – very high speed

Question 33

Customer complaints of excessive hydraulic hose breakage. What five things do you need to ask?

Answer 33

What is pressure rating for the hose? What is the system pressure during work? How much movement and is result total flex? Any other equipment in the area and/or what is the working environment? What is the pressure rating of the entire system? How are the hoses connected to the various parts. What are the angles of connection?

Question 34

A rubber return line keeps breaking. What are the possible causes?

Answer 34

``` heat Plugged relief valve misdirected directional valve incompatibility of the rubber to the fluid substandard material incorrectly sized ```

Question 35

What does NPT stand for in relation to fluid conductors?

Answer 35

National pipe thread

Question 36

__________ pressure rates the useful limit of hosing.

Answer 36

Burst

Question 37

When pressure increases, the length of hosing __________.

Answer 37

Decreases