Module 8 Oxy Fuel Equipment

Question 1

Which gas is produced using the air liquefaction process?
A) acetylene
B) oxygen
C) propane
D) hydrogen

Answer 1

B) oxygen

Question 2

Explain why oxygen is dangerous

Answer 2

It is combustible and may react violently with some materials

Question 3

For efficient heating and cutting operations oxygen must have a minimum purity of
A) 80%
B) 93%
C) 98.6%
D) 99.5%

Answer 3

D) 99.5%

Question 4

Oil or grease in contact with pure oxygen can:

Answer 4

React violently and cause an explosion

Question 5

Explain how acetylene gas is produced

Answer 5

By mixing calcium carbide and water in an acetylene generator

Question 6

Define acetylene generator

Answer 6

A machine used to produce acetylene gas by bringing specific amounts of granulated, calcium, carbide, and water together under strictly controlled conditions. the vapours acetylene gas is collected from the generator as it is produced, and it is placed into specifically design cylinders for storage and use

Question 7

Fill in the blanks with the correct numbers associated with acetylene.
A) the critical pressure is_______kPa(_______psi)
B) the maximum safe working pressure is ________kPa(_______psi)
C) the explosive limit in error is from_______% to ________%
D) the explosive limit in pure oxygen is from ________% to ________%

Answer 7

A) 193kPa or 28psi
B) 103kPa or 15psi
C) 2.5% to 80%
D) 3% to 93%

Question 8

List for fuel gases used for heating and cutting

Answer 8

Acetylene, propane, natural gas, propylene

Question 9

List two methods used for storing oxygen

Answer 9

1. As a liquid in a cryogenic container like a thermos bottle
2. Stored as a gas in high-pressure cylinders

Question 10

And the safety device used on oxygen cylinders and what is its bursting pressure?

Answer 10

It is a metal ruptured disc that has a bursting pressure of about 22,000 kPa or 3200 psi

Question 11

Compare the pressures and contents of a full-size oxygen cylinder with a half size cylinder

Answer 11

The pressure is the same for both cylinders, but the volume of the gas in the half side cylinder is half that of the full-size cylinder

Question 12

Explained why fuel gas cylinders have left-hand threads and non-fuel gas cylinders have right hand threads

Answer 12

It’s a safety feature that insures the equipment is not interchanged or hooked up incorrectly

Question 13

Explain why an acetylene cylinder is filled with a porous material

Answer 13

The poorest material prevents a large volume of free acetylene gas from accumulating under high-pressure to keep the acetylene stable

Question 14

State the location and purpose of fusible metal plugs

Answer 14

Fusible plugs are located on the top and bottom of acetylene cylinders in case of fire. They melt at approximately 100°C or 212°F, providing a controlled release of gas, which helps to prevent an explosion of the cylinder

Question 15

State two safety precautions used to prevent acetone loss

Answer 15

1. Keep acetylene cylinders in vertical positions during storage and use.
2. Do not exceed the draw limit.

Question 16

What should be done before the cylinder valve protective caps are removed?
A) cylinder should be pressure tested
B) cylinder should be secured
C) cylinder valve should be cracked
D) equipment should be lubricated and ready for installation

Answer 16

B) cylinder should be secured

Question 17

In order to protect the regulator gauges from being damaged
A) only use regulators with a preset stage
B) release the adjusting screw before you open the cylinder valve
C) engage the adjusting, screw to allow unrestricted gas flow
D) use only gauges equipped with heavy duty bourdon tubes

Answer 17

B) release the adjusting screw before you open the cylinder valve

Question 18

Which type of regulator fitting requires a fibre washer

Answer 18

A flat faced fitting found on some acetylene regulator/cylinder valves

Question 19

Why are cylinder valves cracked before the regulators are attached?

Answer 19

To remove dust or dirt from the cylinder valve

Question 20

How should you check for leaks on oxy fuel equipment?
A) and open flame
B) a spark lighter
C) spray with anti-spatter solution
D) apply a suitable leak detection fluid

Answer 20

D) apply a suitable leak detection fluid

Question 21

When shutting down an oxy fuel outfit you should
A) close the cylinder valves and bleed the system
B) close the valves and bleed the system
C) back off the regulator screws and bleed the system
D) roll up the hoses and remove the welding tip

Answer 21

A) close the cylinder valves and bleed the system

Question 22

Regarding shutting down an oxy fuel outfit answer, true, or false to the following
A) hoses are rolled up_______
B) torch valves are closed ________
C) regulator, adjusting screws are disengaged_______
D) cylinder valves are closed_________
E) shut down, is done at the end of each work shift _______

Answer 22

All statements are true

Question 23

Why are regulators used for oxy fuel heating, and cutting operations?

Answer 23

To maintain a constant working and delivery pressure

Question 24

What precaution should be taken when regulators are to be stored for extended periods of time?

Answer 24

Turn in the working pressure, adjusting, screw enough to release the spring pressure on the diaphragm to move the valve off the valve seat

Question 25

List two types of regulators and briefly explain the operation of each type

Answer 25

1. Single stage regulators reduce source pressure to working pressure in one step.
2. Two stage regulators reduce source pressure to working pressure in two steps.

Question 26

What does creep mean as it relates to welding equipment regulators

Answer 26

Creep is a condition where the high-pressure valve is not seated so gas leaks into the low pressure side and causes an uncontrolled pressure rise in the low pressure chamber

Question 27

How would you safely repair an acetylene hose?

Answer 27

Cut out the damaged area and splice using CGA approved fittings of yellow brass, iron or steel

Question 28

What colour is the oxygen hose?

Answer 28

Green

Question 29

Which hose fittings have a left-handed thread?

Answer 29

The fuel gas fittings have a left-handed thread

Question 30

List two tools that may be used to properly clean a dirty tip

Answer 30

1. Tip cleaners.
2. Tip drills.

Question 31

On page 47 of module eight oxy fuel equipment there is a diagram label the diagram

Question 32

On page 48 of module eight oxy fuel equipment label the diagram on question 32

Question 33

What is the difference between a backfire and a flashback?

Answer 33

A backfire occurs in the mixer and tip. A flashback occurs beyond the mixer into the hose and regulator on the low pressure side.

Question 34

List four causes of backfires

Answer 34

1. Two little gasp.
2. Obstruction of gas flow.
3. Loose or faulty connections between the tip and mixer.
4. A hot tip.

Question 35

List four causes of flashbacks

Answer 35

1. Grossly unequal pressures.
2. Mildly unequal pressures plus an obstruction of the tip.
3. Failing to purge the lines.
4. Faulty manipulation of valves.

Question 36

Describe a burn back

Answer 36

A burnback is combustion that takes place steadily in the tip and mixer of the torch

Question 37

Why do you purge each line individually on an oxy fuel outfit before lighting the torch?

Answer 37

To prevent flashbacks, you purge the lines of any air or explosive mixture that may be present

Question 38

When changing heating tips to a different size why is there a need to rebalance gas pressures?
A) to ensure the tip is free of dirt
B) because the orifice size is different
C) to prevent a burn back
D) to ensure the proper gases are in their respective hoses

Answer 38

B) because the orifice size is different

Question 39

Why should the acetylene torch valve always be set so the flame is above the smoke range

Answer 39

It ensures that adequate gas flow is maintained and reduces the possibility of backfires and burn backs

Question 40

Define speed of flame propagation

Answer 40

The speed that the flame travels in premixed gases