C-4 Oxy-Fuel

Question 1

Oxy Fuel gasses

Answer 1

process of gass cutting requires two gasses and a source of ignition.

Question 2

oxygen

Answer 2

20. 8% of atmosphere
    - supports combustion
    - no color or oder

Question 3

Hoses for oxyacetylene

Answer 3

made from rubber and cotton

must shut off oxygen to extinguish fire

Question 4

Oil or grease and oxygen

Answer 4

if either is brought into contact with pure oxygen under slight pressure explosion can occur

Question 5

Steel and oxygen

Answer 5

if brought to correct temp (red hot) and brought into contact with oxygen it can burn rapidly.

Question 6

Acetylene

Answer 6

• compound created from two atoms of carbon and two atoms of hydrogen.
• generates high heat when burned
• widest range of flammability
• flame can reach 3300°C
• should not be stored or used at pressures over 15psi
• never use copper or red brass for fittings and tubing
  use only yellow brass iron or steel

Question 7

unstable gas

Answer 7

Acetylene

Question 8

MAPP gass

Answer 8

• stable mixture of methylacetylene and propadiene
• shipped in low-pressure cylinders so must be used upright (liquid form)
• ## safer to use

Question 9

flame temp for MAPPgass

Answer 9

2900°C very stable and inexpensive

Question 10

Natural gas

Answer 10

• preferred in areas where it can be piped in eliminating handling of fuel cylinders
• not liquid form

Question 11

Flame temp of natural gas

Answer 11

2540°C slower cuts but very inexpensive

Question 12

Propane Gas

Answer 12

• supplied in liquid form low pressure cylinders.
• easy safe to handle
• flame temp is 2540°

Question 13

Gas cylinders

Answer 13

• forged from one piece of high grade steel

- slightest sign of damage cylinder is withdrawn

Question 14

Cylinder safety devices

Answer 14

• located in valve. consists of a pressure or rupture disk.

- this will burst and release cylinder oxygen into the air when excessive pressure buildup occurs.

Question 15

Acetylene cylinder

Answer 15

filled with porous material called agamassan, asbestos, charcoal or diatomaceous earth. this filler material is saturated with acetone which has the ability to absorb acetylene gas and is used in cylinders to make them safe at high pressures

Question 16

acetylene cylinder valves

Answer 16

turn pressure valve 1/4 turn then 1/2 turn. what handle is rotated counter clockwise (opening) pressure is released from the seal.

Question 17

acetylene Cylinder safety device

Answer 17

heat activated plugs in top and bottom of cylinder. heat causes them to melt which then releases the cylinder content to avoid unsafe pressure rise.

Question 18

Liquid Fuel Cylinders

Answer 18

propane and MAPP are liquids and stored in cylinders

• when shipped full there i still space above liquid for gas to occupy
• this gas escapes when valve is open
• reducing pressure on top of liquid.
• this allows the liquid to “boil off”

Question 19

Oxygen Regulator

Answer 19

• right hand thread connection
• 0 - 4000 psi
• working pressure gauge usually calibrated from 0 - 200 psi
• OXYGEN should be printed on body and on one or booth gauges

Question 20

Acetylene regulators

Answer 20

• left handed threads
• cylinder pressure gauge from 0 - 400 psi
• working pressure gauge from 0 - 30 psi
• working pressure gauge has red line from 15 - 30 psi
• acetylene should be printed on body and one or both gauges

Question 21

oxy fuel Fittings

Answer 21

all fittings and connectors used in the hookup of hose to the regulators and torch body are made of brass
- this prevents sparks it its banged up against another material
- * right handed for oxygen
- ** left handed for acetylene
-

Question 22

Backfire

Answer 22

when torch or flame burns back into the welding or cutting tip making a popping sound.

Question 23

Flashback

Answer 23

occurs when backfire goes beyond the tip, through the hose to the regulator.

Question 24

Reverse flow check valve (RFCV)

Answer 24

put in hoses compression spring holds the valve closed. when operator opens the regulator and torch valves, RFCV opens to permit normal gas flow then snaps shut if the flow is reversed.