Oxy-Fuel Gas Cylinders and Equipment Section 5-6

Question 1

What is the main job of a gas pressure regulator?

a. To make the gas pressure higher
b. To control the torch’s temperature
c. To slow down the gas flow
d. To lower the strong cylinder pressure to the right pressure for the torch

Answer 1

d. To lower the strong cylinder pressure to the right pressure for the torch

A gas pressure regulator is like a control valve for gas. Its main job is to take the high pressure from a gas cylinder and reduce it to a safe and usable pressure for whatever one’s using the gas for, like a torch or a burner. It makes sure that the pressure of the gas coming out is just right for the equipment being used.

Question 2

Oxygen has _______ pressure setting compared to acetylene.

a. The same
b. A higher
c. A lower
d. About the same

Answer 2

b. A higher

Oxygen has a higher pressure setting compared to acetylene.

Question 3

A recommended operating pressure for the cutting torch falls within the range of:

a. 140 kPa (20 psi) for oxygen and 100 kPa (15 psi) for acetylene
b. 240 kPa (35 psi) for oxygen and 200 kPa (30 psi) for acetylene
c. 275 kPa (40 psi) for oxygen and 69 kPa (10 psi) for acetylene
d. 400 kPa (60 psi) for oxygen and 138 kPa (20 psi) for acetylene

Answer 3

c. 275 kPa (40 psi) for oxygen and 69 kPa (10 psi) for acetylene

The oxygen CYLINDER pressure is typically in the range of 15 MPa (2,200 psi)

Question 4

Which device is installed at the cylinder valves for oxygen, acetylene, or other gases to decrease the cylinder pressure to a suitable working pressure at the torch tip?

a. Flow meters
b. Safety valves
c. Pressure regulators
d. Hose connectors

Answer 4

c. Pressure regulators

A pressure regulator is a device that controls the pressure of a gas coming from a high-pressure source, like a cylinder, and lowers it to a safe and consistent level for use. It’s like a valve that adjusts the flow of gas to ensure it’s just right for whatever you’re using it for, like welding or cooking.

Question 5

Which of the following is typically used to identify pressure regulators?

a. The colour of the casing
b. The manufacturer’s logo
c. The type of gas for which they are used
d. The size of the pressure gauge

Answer 5

c. The type of gas for which they are used

For example, an oxygen pressure regulator body will have “oxygen” printed on it and will usually be green in colour.

An acetylene pressure regulator body will have “acetylene” printed on it and will usually be red in colour.

Although exact identification and other features vary with different manufacturers,

Question 6

Which components make up a pressure regulator?

a. A nozzle, rigid diaphragm, and gears.
b. A cylinder, piston, and levers.
c. A seat, flexible diaphragm, and springs.
d. A valve, gearbox, and bearings.

Answer 6

c. A seat, flexible diaphragm, and springs.

The “seat” is like a tight seal or a stopper where the gas flow is controlled. It’s a fixed part against which the flexible diaphragm presses to regulate the gas pressure.

A “diaphragm” is like a thin, stretchy membrane that moves to control the flow of gas. It acts like a barrier between high-pressure and low-pressure areas, flexing to adjust the gas flow and keep it at the right level.

The “springs” are like little coils that help control the pressure. They push against the diaphragm to keep the pressure steady and just right for what you’re using the gas for.

Question 7

What is the range of pressure typically displayed on oxygen cylinder pressure regulator gauges?

a. 0-20,000 kPa (0-2,900 psi)
b. 0-30,000 kPa (0-4,350 psi)
c. 0-25,000 kPa (0-3,625 psi)
d. 0-27,500 kPa (0-4,000 psi)

Answer 7

d. 0-27,500 kPa (0-4000 psi)

This gauge tells you how much gas is left in the cylinder before you start using it.

Question 8

Which of the following best describes the range of a working pressure gauge for oxygen?

a. 0-100 kPa (0-15 psi)
b. 0-300 kPa (0-45 psi)
c. 0-200 kPa (0-30 psi)
d. 0-400 kPa (0-60 psi)

Answer 8

c. 0-200 kPa (0-30 psi)

This gauge shows you the pressure of the gas coming out of the cylinder and going into your equipment.

Question 9

What is the typical pressure range shown on acetylene cylinder pressure regulator gauges?

a. 0-5 MPa (0-725 psi)
b. 0-3.5 MPa (0-500 psi)
c. 0-2.7 MPa (0-400 psi)
d. 0-1.5 MPa (0-225 psi)

Answer 9

c. 0-2.7 MPa (0-400 psi)

AKA 0-2700 kPa (0-400 psi)

This gauge tells you how much gas is left in the cylinder before you start using it.

Question 10

Which of the following best describes the range of a working pressure gauge for acetylene?

a. 0-100 kPa (0-15 psi)
b. 0-150 kPa (0-22 psi)
c. 0-200 kPa (0-30 psi)
d. 0-250 kPa (0-36 psi)

Answer 10

c. 0-200 kPa (0-30 psi)

Although acetylene working pressure must be kept below 103 kPa (15 psi)

This gauge shows you the pressure of the gas coming out of the cylinder and going into your equipment.

Question 11

Which of the following statements accurately describes the recommended working pressure for acetylene?

a. The acetylene working pressure should exceed 100 kPa (14.5 psi).
b. The acetylene working pressure should be precisely 130 kPa (19 psi).
c. The acetylene working pressure must be kept below 103 kPa (15 psi).
d. The acetylene working pressure is irrelevant for safe usage.

Answer 11

c. The acetylene working pressure must be kept below 103 kPa (15 psi).

This is to prevent the unstable acetylene gas from exploding.

Question 12

Which feature distinguishes the hex nut on an acetylene pressure regulator from that on an oxygen pressure regulator?

a. The acetylene hex nut is larger in size.
b. The acetylene hex nut is smooth.
c. The acetylene hex nut is grooved.
d. The acetylene hex nut is painted red.

Answer 12

c. The acetylene hex nut is grooved.

Question 13

Which feature distinguishes the hex nut on an oxygen pressure regulator from that on an acetylene pressure regulator?

a. The oxygen hex nut is larger in size.
b. The oxygen hex nut is grooved.
c. The oxygen hex nut is painted blue.
d. The oxygen hex nut is smooth.

Answer 13

d. The oxygen hex nut is smooth.

Question 14

Which statement accurately describes the threading of connections for gas pressure regulators?

a. Both oxygen and fuel gas pressure regulators have right-hand threads.
b. Both oxygen and fuel gas pressure regulators have left-hand threads.
c. The connections of oxygen pressure regulators have right-hand threads, while fuel gas pressure regulators have left-hand threads.
d. The connections of oxygen pressure regulators have left-hand threads, while fuel gas pressure regulators have right-hand threads.

Answer 14

c. The connections of oxygen pressure regulators have right-hand threads, while fuel gas pressure regulators have left-hand threads.

This makes it impossible to connect a pressure regulator or hoses to the wrong cylinder.

Question 15

Which classification system is used to categorize gas cylinder pressure regulators based on the number of pressure regulation steps?

a. Primary and Secondary regulators
b. Low and High-pressure regulators
c. Single-stage and Two-stage regulators
d. Initial and Final regulators

Answer 15

c. Single-stage and Two-stage regulators

Gas cylinder pressure regulators are categorized based on how many steps they use to control the pressure of the gas.

Question 16

Which type of regulator typically provides a more stable and smooth working pressure for high pressure cylinders?

a. Single-stage regulator
b. Two-stage regulator
c. Both types provide equally stable working pressure
d. None of the above

Answer 16

b. Two-stage regulator

a two-stage regulator provides a more stable and smooth working pressure because it reduces the pressure in two steps instead of just one. This means it can handle variations in pressure from the cylinder better, giving you a steadier flow of gas for your work.

Question 17

Which of the following statements accurately describes the characteristics of a single-stage pressure regulator?

a. It provides finer control over pressure compared to two-stage regulators.
b. It is typically used with individual cylinders.
c. It is more expensive and complex in construction than a two-stage regulator.
d. Working pressure tends to drift downward as the cylinder pressure diminishes, requiring periodic adjustments.

Answer 17

d. Working pressure tends to drift downward as the cylinder pressure diminishes, requiring periodic adjustments.

Question 18

What distinguishes a single-stage pressure regulator from a two-stage regulator?

a. Single-stage regulators are more commonly used in industrial applications.
b. Two-stage regulators are typically used with individual cylinders.
c. Single-stage regulators provide more precise control over pressure.
d. Two-stage regulators maintain a more constant working pressure as cylinder pressure decreases.

Answer 18

d. Two-stage regulators maintain a more constant working pressure as cylinder pressure decreases.

Question 19

Which type of system is a single-stage pressure regulator typically used with?

a. Bulk system or manifold system
b. Individual cylinder
c. High-pressure system
d. Low-pressure system

Answer 19

a. Bulk system or manifold system

Question 20

What are the characteristics of a single-stage pressure regulator?

a. It provides finer control over pressure compared to two-stage regulators.
b. It is typically used with individual cylinders.
c. It is less expensive and simpler in construction than two-stage regulators.
d. It maintains constant working pressure regardless of cylinder pressure.

Answer 20

c. It is less expensive and simpler in construction than two-stage regulators.

Question 21

How does the control over pressure of a single-stage regulator compare to that of a two-stage regulator?
a. It provides more precise control.
b. It provides less precise control.
c. It provides equal control.
d. It provides no control over pressure.

Answer 21

b. It provides less precise control

Question 22

Which type of regulator provides more precise regulation over a wide range of varying inlet pressures?

a. Single-stage pressure regulator
b. Double-stage pressure regulator
c. Three-stage pressure regulator
d. Variable-stage pressure regulator

Answer 22

b. Double-stage pressure regulator

Question 23

Which type of pressure regulator is utilized when the cylinder pressure is reduced to working pressure in two steps?

a. Single-stage pressure regulator
b. Multi-stage pressure regulator
c. Dual-action pressure regulator
d. Two-stage pressure regulator

Answer 23

d. Two-stage pressure regulator

Question 24

What is the primary function of the first stage in a two-stage pressure regulator?

a. To maintain the cylinder pressure at its maximum level
b. To reduce the gas pressure to a safe level for immediate use
c. To decrease the gas pressure to intermediate levels
d. To regulate the gas flow to the desired rate

Answer 24

c. To decrease the gas pressure to intermediate levels

Question 25

What pressure range does the first stage of a two-stage pressure regulator typically drop the cylinder pressure to?

a. Less than 100 kPa (15 psi)
b. Between 500 and 800 kPa (75 and 115 psi)
c. Between 1,200 and 2,800 kPa (180 and 400 psi)
d. More than 5,000 kPa (725 psi)

Answer 25

c. Between 1,200 and 2,800 kPa (180 and 400 psi)

Question 26

Which function does the second stage perform in a two-stage pressure regulator?

a. It increases the intermediate pressure.
b. It maintains the intermediate pressure constant.
c. It reduces the intermediate pressure to the desired working pressure.
d. It switches between different working pressures.

Answer 26

c. It reduces the intermediate pressure to the desired working pressure.

Question 27

Why are two-stage cylinder pressure regulators preferred over single-stage regulators?

a. They are cheaper.
b. They have a simpler design.
c. They deliver a more constant pressure with finer control.
d. They require less maintenance.

Answer 27

c. They deliver a more constant pressure with finer control.

Question 28

What happens to the gas flow rate in single-stage cylinder pressure regulators as the cylinder pressure drops?

a. It increases.
b. It decreases.
c. It remains constant.
d. It fluctuates unpredictably.

Answer 28

d. It fluctuates unpredictably.

Question 29

Why are two-stage cylinder pressure regulators recommended for precise cutting jobs?

a. They are cheaper than single-stage regulators.
b. They require frequent readjustment.
c. They offer more stable gas flow.
d. They are easier to install.

Answer 29

c. They offer more stable gas flow.

Question 30

In which types of cutting operations are two-stage pressure regulators commonly used?

a. Only in manual cutting operations.
b. Only in automatic cutting operations.
c. Only in machine cutting operations.
d. In both automatic and machine cutting operations

Answer 30

d. In both automatic and machine cutting operations

Question 31

Why are two-stage pressure regulators more common in automatic and machine cutting applications?

a. They are less precise compared to single-stage regulators.
b. They are easier to operate manually.
c. They can handle higher gas pressures.
d. They provide finer control, which is crucial for automated processes.

Answer 31

d. They provide finer control, which is crucial for automated processes.

Question 32

Which type of pressure regulator is recommended for accurate cutting and welding operations?

a. Single-stage pressure regulators
b. Two-stage pressure regulators
c. Variable pressure regulators
d. Fixed pressure regulators

Answer 32

b. Two-stage pressure regulators

Question 33

What precaution should be taken with the pressure-adjusting screw in cylinder pressure regulators?

a. Tighten it firmly before opening the cylinder valve.
b. Keep it at the maximum setting to ensure proper gas flow.
c. Back it out until it moves freely before opening the cylinder valve.
d. Leave it untouched, as it does not affect the gas flow.

Answer 33

c. Back it out until it moves freely before opening the cylinder valve.

Question 34

Why is it important to back out the pressure-adjusting screw in cylinder pressure regulators?

a. To increase the gas flow rate.
b. To prevent damage to the regulator mechanism.
c. To decrease the gas pressure in the cylinder.
d. To make it easier to open the cylinder valve.

Answer 34

b. To prevent damage to the regulator mechanism.

Question 35

What risk is associated with allowing a sudden surge of cylinder gas into the pressure regulator?

a. Decreased gas pressure at the torch tip.
b. Damage to the cylinder valve.
c. Potential damage to the regulator mechanism.
d. Improved performance of the pressure regulator.

Answer 35

c. Potential damage to the regulator mechanism.

Question 36

What is the potential consequence of a damaged pressure regulator due to a sudden surge of cylinder gas?

a. Reduced gas consumption.
b. Increased safety during operation.
c. Risk of personal injury.
d. Enhanced gas flow control.

Answer 36

c. Risk of personal injury.

Question 37

What should you check for after attaching hoses and a torch to cylinder pressure regulators?

a. The colour of the hoses
b. The length of the hoses
c. An increase or “creep” in the working-pressure gauge
d. The temperature of the regulator

Answer 37

c. An increase or “creep” in the working-pressure gauge

Question 38

What is the possible cause of an increase or “creep” in the working-pressure gauge after attaching hoses and a torch to cylinder pressure regulators?

a. Faulty torch valves
b. Loose hose connections
c. Faulty seat valve in the regulator
d. Insufficient gas pressure

Answer 38

c. Faulty seat valve in the regulator

Question 39

What action should be taken if there is an increase or “creep” in the working-pressure gauge after attaching hoses and a torch to cylinder pressure regulators?

a. Continue using the equipment as usual
b. Tighten the hose connections
c. Adjust the torch valves
d. Repair the faulty seat valve in the regulator before further use

Answer 39

d. Repair the faulty seat valve in the regulator before further use

Question 40

What is the recommended precaution when connecting a pressure regulator to a gas cylinder?

a. Use pliers or a pipe wrench to tighten connections.
b. Always check for the correct pressure regulator before connecting.
c. Force connections if they don’t fit properly.
d. Connect the regulator without using a cylinder wrench.

Answer 40

b. Always check for the correct pressure regulator before connecting.

Question 41

Why is it important to verify the correct pressure regulator before connecting it to a gas cylinder?

a. To save time during the connection process.
b. To ensure proper functionality and safety.
c. To increase gas pressure.
d. To avoid using a cylinder wrench.

Answer 41

b. To ensure proper functionality and safety.

Question 42

What tool should be used to tighten connections when attaching a pressure regulator to a gas cylinder?

a. Pliers
b. Pipe wrench
c. Cylinder wrench
d. Screwdriver

Answer 42

c. Cylinder wrench

Question 43

What should you avoid using on the connections of cylinder pressure regulators?

a. Grease
b. Oil-based pipe compound
c. Teflon tape
d. All of the above

Answer 43

d. All of the above

Question 44

Who should repair pressure regulators according to safety guidelines?

a. Any experienced individual
b. Any individual with basic mechanical skills
c. A trained technician
d. The user themselves

Answer 44

c. A trained technician

Question 45

What should you never attempt to do with a faulty pressure regulator?

a. Label it as faulty
b. Place it in an area where it will not be used
c. Repair it
d. Order a replacement

Answer 45

c. Repair it

Question 46

What precaution should be taken when handling cylinder pressure regulators?

a. Drop them gently to ensure they are securely in place.
b. Misuse them to test their durability.
c. Handle them with care and never drop or misuse them.
d. Handle them loosely to avoid crushing them.

Answer 46

c. Handle them with care and never drop or misuse them.

Question 47

Why is it important to handle cylinder pressure regulators with care?

a. To test their durability.
b. To ensure they are securely in place.
c. They have precise internal mechanisms.
d. None of the above.

Answer 47

c. They have precise internal mechanisms.

Question 48

What action should be taken when transporting or removing pressure regulators from service?

a. Turn the working pre-adjusting screw as much as possible.
b. Leave the pressure regulators as they are.
c. Turn the working pre-adjusting screw just enough to take the pressure off the inlet seat valves.
d. Completely disassemble the pressure regulators for transportation.

Answer 48

c. Turn the working pre-adjusting screw just enough to take the pressure off the inlet seat valves.

Question 49

What is the purpose of turning the working pre-adjusting screw when transporting or removing pressure regulators from service?

a. To increase pressure on the inlet seat valves.
b. To ensure the pressure regulators are tightly secured.
c. To prevent sticking and corrosion of the seat.
d. None of the above.

Answer 49

c. To prevent sticking and corrosion of the seat.

Question 50

Which statement accurately describes the threading of Compressed Gas Association (CGA) fittings on cylinder pressure regulators?

a. CGA fittings always have right-hand threads.
b. CGA fittings always have left-hand threads.
c. CGA fittings can have either right-hand or left-hand threads.
d. CGA fittings have reverse threads compared to standard fittings.

Answer 50

c. CGA fittings can have either right-hand or left-hand threads.

Question 51

What precaution should be taken when replacing fittings on a cylinder pressure regulator?

a. Use any available fitting for replacement.
b. Tighten the fitting as much as possible.
c. Always use an exact replacement fitting.
d. Only use fittings with left-hand threads.

Answer 51

c. Always use an exact replacement fitting.

Question 52

What is the consequence of replacing a CGA 580 fitting with a CGA 680 fitting on a regulator?

a. It will not affect the regulator’s performance.
b. It will decrease the pressure in the regulator.
c. It will over-pressurize the regulator.
d. It will cause the regulator to leak gas.

Answer 52

c. It will over-pressurize the regulator.

This can cause serious injury and damage.

Question 53

What is a crucial requirement for hoses used in cylinder pressure regulators?

a. Rigidity for stability
b. Stiffness for less risk of mobility
c. Flexibility for mobility and manipulation

Answer 53

c. Flexibility for mobility and manipulation

Question 54

Why must hoses used in cylinder pressure regulators be able to withstand high line pressures?

a. To minimize gas leakage
b. To increase gas flow rate
c. To reduce equipment weight
d. To enhance portability

Answer 54

a. To minimize gas leakage

Question 55

What utility and safety requirements must hoses for cylinder pressure regulators meet?

a. They must be resistant to extreme temperatures
b. They must be able to conduct electricity
c. They must be flexible and durable
d. They must be transparent for visual inspection

Answer 55

c. They must be flexible and durable

Question 56

What is the structure of the hoses used in cylinder pressure regulators for fuel gases and oxygen?

a. Single-layer rubber with fabric reinforcement
b. Two or three rubber layers, each separated by a layer of strong fabric
c. Three rubber layers without any fabric reinforcement
d. A single rubber layer without any fabric reinforcement

Answer 56

b. Two or three rubber layers, each separated by a layer of strong fabric

Question 57

What colour is typically used for the oxygen hose in cylinder pressure regulators?

a. Red or Yellow
b. Green or Black
c. Black or Blue
d. Blue or Red

Answer 57

b. Green or Black

Question 58

Which color is commonly assigned to the fuel gas (acetylene) hose in cylinder pressure regulators?
a. Yellow
b. Black
c. Green
d. Red

Answer 58

d. Red

Question 59

Why are hoses for cylinder pressure regulators reinforced with two layers?

a. To increase flexibility
b. To decrease durability
c. To avoid kinking and wear
d. To simplify maintenance

Answer 59

c. To avoid kinking and wear

Question 60

What is the purpose of the outside layer of rubber in most oxy-fuel gas hoses?

a. To reduce flexibility
b. To increase tangling
c. To prevent tangling
d. To decrease durability

Answer 60

c. To prevent tangling

Question 61

What factor determines the sizing of oxy-fuel hoses in cylinder pressure regulators?

a. The length of the hose
b. The outside diameter of the hose
c. The inside diameter of the inner tube
d. The material of the hose

Answer 61

c. The inside diameter of the inner tube

Question 62

Which of the following is the most common size for oxy-fuel hoses used in light-duty cutting and welding?

a. 4.0 mm
b. 5mm
c. 6.4 mm
d. 8mm

Answer 62

b. 5mm (3/16 in)

Question 63

Why is a large-diameter hose recommended for cutting thick material?

a. To decrease gas flow
b. To increase gas pressure
c. To deliver the required oxygen and fuel-gas
d. To improve maneuverability

Answer 63

c. To deliver the required oxygen and fuel-gas

Question 64

What is the recommended solution for overcoming greater pressure drops in long lengths of hose connected to cylinder pressure regulators?

a. Increasing the gas flow rate
b. Using a higher regulator pressure
c. Decreasing the diameter of the hose
d. Using a longer hose

Answer 64

b. Using a higher regulator pressure

Question 65

Why is a larger diameter hose recommended for delivering gas from cylinder pressure regulators to the torch?

a. To reduce the gas flow rate
b. To increase pressure drops
c. To decrease the volume of gas delivered
d. To overcome greater pressure drops and deliver more volume

Answer 65

d. To overcome greater pressure drops and deliver more volume

Question 66

What should be checked regarding hose size when using cylinder pressure regulators?

a. Shops supervisors’ recommended torch size
b. The gas flow rate through the hose
c. The manufacturer’s oxy-fuel gas hose size
d. The pressure rating of the hose material

Answer 66

c. The manufacturer’s oxy-fuel gas hose size

Question 67

Why are shorter hose lengths recommended for safety reasons when using cylinder pressure regulators?

a. To reduce the risk of gas leaks
b. To increase the pressure drop
c. To decrease gas flow rate
d. To improve the efficiency of the torch operation

Answer 67

a. To reduce the risk of gas leaks

Question 68

Which grade of oxy-fuel gas hose is suitable for use with liquid fuel gases?

a. Grade T
b. Grade R
c. Grade G
d. Grade L

Answer 68

a. Grade T

Question 69

Which grade of oxy-fuel gas hose is specifically designed for use with acetylene?

a. Grade T
b. Grade R
c. Grade A
d. Grade G

Answer 69

b. Grade R

Question 70

+True or False. Grade R oxy-fuel gas hoses are suitable for acetylene.

a. True
b. False

Answer 70

a. True

Question 71

Which grade of oxy-fuel gas hose is versatile and can be used with all fuel gases, including acetylene?

a. Grade T
b. Grade R
c. Grade F
d. Grade G

Answer 71

a. Grade T

Question 72

What precautions should be taken to prevent fires or explosions related to oxy-fuel gas hoses?

a. Ensuring hoses are coiled and supported
b. Cleaning hoses with oil and grease
c. Storing hoses in dry direct sunlight
d. Securing puncture holes with grade A tape

Answer 72

a. Ensuring hoses are coiled and supported

Question 73

What should be done with damaged oxy-fuel gas hoses?

a. Keep using them if the damage is minor.
b. Replace or repair them.
c. Wrap them with tape for temporary fixes.
d. Ignore the damage if it’s on the exterior.

Answer 73

b. Replace or repair them.

Question 74

Why should oxy-fuel gas hoses be purged before use and after every cylinder change?
a. To increase the flexibility of the hoses.
b. To decrease the risk of kinking.
c. To prevent dirt or debris from clogging the torch passages.
d. To remove excess smell from gas.

Answer 74

c. To prevent dirt or debris from clogging the torch passages.

Question 75

What type of air should be used when blowing out hoses?

a. Air with oil content.
b. Oil-less compressed air.
c. Air mixed with gasoline.
d. Air from a regular compressor.

Answer 75

b. Oil-less compressed air.

Question 76

What should never be used for repairs on oxy-fuel gas hoses?

a. Tape.
b. Welding tacks.
c. Glue.
d. All of the above

Answer 76

d. All of the above

Question 77

Which material is used to make fittings and connectors for oxy-fuel hoses, regulators, and torch bodies?

a. Steel
b. Aluminum
c. Brass alloys
d. Copper

Answer 77

c. Brass alloys

Question 78

True or False. Brass alloys are preferred for making fittings and connectors because they do not corrode or create dangerous by-products when exposed to oxy-fuel gases and do not generate sparks if they contact other metals or materials.

a. True
b. False

Answer 78

a. True

Question 79

What is the purpose of using yellow brass fittings for oxy-fuel gas hoses?

a. To increase flexibility
b. To reduce weight
c. To avoid generating sparks
d. To enhance gas flow

Answer 79

c. To avoid generating sparks

Question 80

How can you identify the threading on acetylene hose fittings?

a. By the colour of the hose
b. By the presence of a groove cut into the fitting
c. By the material used for the fitting
d. By the size of the fitting

Answer 80

b. By the presence of a groove cut into the fitting

Question 81

Why are acetylene fittings distinctly different from oxygen fittings?

a. To prevent gas leaks
b. To enhance compatibility
c. To facilitate interchangeability
d. To prevent accidental interchange

Answer 81

d. To prevent accidental interchange

Question 82

Which materials are recommended for use in acetylene gas systems?

a. Copper or red brass
b. Aluminium or plastic
c. Yellow brass, iron, or steel
d. Titanium or ceramic

Answer 82

c. Yellow brass, iron, or steel

Question 83

Why are copper or red brass fittings not recommended for acetylene hose fittings?

a. They are too expensive.
b. They are prone to corrosion.
c. They can react with acetylene to form a dangerous residue.
d. They do not provide a secure connection.

Answer 83

c. They can react with acetylene to form a dangerous residue (Acetylide).

Question 84

What precaution should be taken before using fittings on oxy-fuel gas hoses?

a. They should be cleaned with water.
b. They should be lubricated with oil.
c. They should be firmly secured.
d. They should be heated to a certain temperature.

Answer 84

c. They should be firmly secured.

Question 85

What is a backfire in oxy-acetylene equipment?

a. A momentary recession of the flame into the torch tip or mixer.
b. A steady flame burning from the torch tip.
c. A complete extinguishment of the flame without any sound.
d. A continuous flame that does not recede or make any noise.

Answer 85

a. A momentary recession of the flame into the torch tip or mixer,

followed by a loud popping sound.

Question 86

What sound may indicate that the flame has reignited after a backfire?

a. A loud popping sound.
b. A squealing sound.
c. A hissing sound.
d. A crackling sound.

Answer 86

b. A squealing sound.

Question 87

What action should be taken if a backfire occurs in oxy-acetylene equipment?

a. Immediately relight the torch.
b. Close the oxygen and fuel gas valves immediately to check the equipment.
c. Ignore it and continue working.
d. Increase the gas flow to prevent further backfires.

Answer 87

b. Close the oxygen and fuel gas valves immediately to check the equipment.

Question 88

When is a backfire most commonly likely to occur in oxy-acetylene equipment?

a. When working with cold metal.
b. When adjusting the gas flow.
c. When the torch tip touches hot metal.
d. When the equipment is not properly cleaned.

Answer 88

c. When the torch tip touches hot metal.

Question 89

What should be done if backfires continue to occur despite cleaning and purging the equipment?

a. Increase the gas flow.
b. Replace the torch tip.
c. Remove the torch from service for cleaning and possible repair.
d. Ignore it and continue working.

Answer 89

c. Remove the torch from service for cleaning and possible repair.

Question 90

What is a flashback in oxy-fuel torch lines?

a. An unexpected increase in gas pressure
b. A sudden ignition of the gas mixture within the torch or hoses
c. A decrease in flame temperature
d. A decrease in gas flow rate

Answer 90

b. A sudden ignition of the gas mixture within the torch or hoses

Question 91

What can cause a flashback when using oxy-fuel torch lines?

a. Insufficient gas pressure
b. Excessive gas flow rate
c. Presence of contaminants in the gas lines
d. All of the above

Answer 91

d. All of the above

Question 92

What are the potential aftereffects of a flashback?
a. Damage to the torch tip
b. Damage to the hoses
c. Both a and b
d. None of the above

Answer 92

c. Both a and b

Question 93

At what temperature does the burning speed of the gas mixture increase dramatically during a flashback?

a. 150°C
b. 190°C
c. 220°C
d. 250°C

Answer 93

c. 220°C

Question 94

At approximately what temperature can spontaneous ignition and burning of the gas mixture within the tip occur?

a. 220°C
b. 250°C
c. 280°C
d. 315°C

Answer 94

d. 315°C

Question 95

What temperature must the torch tip be kept below to prevent spontaneous ignition of the gas mixture within the tip?

a. 150°C
b. 190°C
c. 220°C
d. 250°C

Answer 95

b. 190°C

Question 96

What is the primary function of flashback arrestors in oxy-fuel torch lines?

a. To increase the flow rate of gas
b. To regulate the temperature of the flame
c. To extinguish flames
d. To create a spark in the torch line

Answer 96

c. To extinguish flames

Question 97

In addition to extinguishing flames, what other function do flashback arrestors serve?

a. They increase the pressure of the gas
b. They regulate the oxygen-to-fuel ratio
c. They prevent the backflow of gas
d. They cool down the torch line

Answer 97

c. They prevent the backflow of gas

Question 98

What happens if certain temperatures and/or pressures are exceeded in a flashback arrestor?

a. The gas flow is increased
b. The flashback arrestor shuts off the gas flow
c. The flashback arrestor ignites
d. The flashback arrestor expands

Answer 98

b. The flashback arrestor shuts off the gas flow

Question 99

How are flashback arrestors typically marked to indicate the direction of gas flow?

a. With a circle
b. With a square
c. With an arrow
d. With a triangle

Answer 99

c. With an arrow

Question 100

Where can flashback arrestors be installed in oxy-fuel torch lines?

a. Only at the torch
b. Only at the regulators
c. Both at the torch and regulators
d. None of the above

Answer 100

c. Both at the torch and regulators

Question 101

What is the primary function of a torch-mounted flashback arrestor?

a. To protect the regulator
b. To prevent flashback from entering the hose
c. To stop the flow of gas
d. To extinguish flames on the torch tip

Answer 101

b. To prevent flashback from entering the hose

Question 102

What is the purpose of a regulator-mounted flashback arrestor?
a. To protect the torch
b. To prevent flashback from going further back to the acetylene bottle
c. To stop the flow of oxygen
d. To extinguish flames on the regulator

Answer 102

b. To prevent flashback from going further back to the acetylene bottle

Question 103

Why won’t a reverse-flow check valve stop a flashback?

a. Because it is not designed for gas flow direction
b. Because it is ineffective in high-pressure systems
c. Because it does not extinguish flames
d. Because it cannot prevent gas from flowing backwards

Answer 103

d. Because it cannot prevent gas from flowing backwards

Question 104

What is the primary function of a reverse flow valve in oxy-fuel torch lines?
a. To increase the flow rate of gases
b. To regulate the temperature of the torch flame
c. To prevent the backflow of gases into the hoses
d. To adjust the pressure of the gases

Answer 104

c. To prevent the backflow of gases into the hoses

Question 105

How does a reverse flow valve function in oxy-fuel torch lines?
a. By allowing the gases to flow in one direction only
b. By mixing oxygen and fuel gases to create a combustible mixture
c. By controlling the speed of the gas flow
d. By shutting off the gas supply in case of an emergency

Answer 105

a. By allowing the gases to flow in one direction only

Question 106

What is he typical life expectancy of a reverse flow check valve?

a. 4 months
b. 8 months
c. 16 months
d. 18 months

Answer 106

18. months

Question 107

Cylinder pressure regulators have how many gauges?

a. 1
b. 2
c. 3
d. 4

Answer 107

c. 2

Question 108

What position should the pressure regulator adjusting knob be set at prior to opening the cylinder valve?

a. Backed out all the way.
b. Threaded in all the way.
c. Threaded in 1-1.5 turns.
d. Threaded halfway.

Answer 108

a. Backed out all the way.

Question 109

What should you shut down first in the event of a flashback?

a. Acetylene cylinder valve.
b. Acetylene valve (torch).
c. Oxygen cylinder valve.
d. Oxygen valve (torch).

Answer 109

d. Oxygen valve (torch).

Question 110

What should you shut down first in the event of a backfire?

a. Acetylene cylinder valve.
b. Acetylene valve (torch).
c. Oxygen cylinder valve.
d. Oxygen valve (torch).

Answer 110

b. Acetylene valve (torch).