Lesson 1 WS- 01- 4

1
Lesson 1 WS- 01- 4 1
Oxy Acetylen Cutting
2
Oxygen
Characteristics
It is the colorless, odorless, tasteless gas that
supports life and makes combustion possible. It
constitutes about one-fifth of the earths
atmosphere (20.99 percent by volume). It is a
transparent, pale blue liquid slightly heavier
than water at temperatures ranging below
approximately -300 F. All elements except the
inert gases combine with oxygen, usually to form
oxides.
Technical specification
Production
Safety
3
Oxygen
Characteristics
Technical specification
Oxygen purity is vital to efficient production.
For example, 99.5 percent pure oxygen can
produce high-quality, flame-cut edges. A drop of
one percent in oxygen purity slows cutting speed
25 percent. At 95 percent oxygen purity, an
oxy-fuel cutting torch will not cut steel at all.
Production
Safety
  WEIGHT WEIGHT GAS GAS LIQUID LIQUID
  POUNDSLb KILOGRAMSKg CUBIC FEETSCF CUBIC METERSNm3 GALLONSGal LITERSL
  1 Pound 1.0 0.4536 12.076 0.3174 0.1050 0.3977
  1 Kilogram 2.205 1.0 26.62 0.6998 0.2316 0.8767
  1 SCF Gas 0.08281 0.03756 1.0 0.02628 0.008691 0.0329
  1 Nm3 Gas 3.151 1.4291 38.04 1.0 0.3310 1.2528
  1 Gal Liquid 9.527 4.322 115.1 3.025 1.0 3.785
  1 L Liquid 2.517 1.1417 30.38 0.7983 0.2642 1.0
4
Oxygen
Characteristics

• Cylinder oxygen is produced from vaporized
  liquid oxygen. Its minimum guaranteed purity is
  99.5 percent.
• Liquid oxygen is classified as Type II by the
  Compressed Gas Association (CGA). CGA Pamphlet
  G-4.3 Type II, Grade B and the United States
  Pharmacopia (USP) specifications are considered
  standards for "commercial" liquid oxygen. A
  variety of other CGA oxygen Grades are available
  on special order. These range from CGA Grade C,
  also 99.5 percent oxygen content to CGA Grade H
  (99.995 percent oxygen). Also available is high
  purity ULSI grade and ultra high purity VLSI
  grade (99.9999 percent pure) liquid oxygen for
  customers requiring stringent purity standards.

Technical specification
Production
Safety
5
Oxygen
Characteristics

• Oxygen makes it much easier for materials to
  ignite. Even materials that would not normally
  burn, like steel wool, will burn in an oxygen
  atmosphere.
• Only equipment "cleaned for Oxygen service"
  should be used for gaseous or liquid oxygen.
  Never use oil or organic lubricants on oxygen
  valves and regulators. Pure oxygen reacts about
  five times faster than air in oxidizing organic
  materials. Spontaneous combustion is likely to
  occur.
• Care is necessary in housekeeping and product
  handling so as not to allow oxygen to contact
  organic materials or any flammable materials.
  Paints, thinners, and cleaning solvents also must
  be kept away from oxygen exposures and no
  ignition sources should be allowed in areas where
  oxygen is stored or used. No smoking is allowed
  in areas where oxygen is used and stored.
• Use clean gloves or hands washed free of any oils
  or grease when handling oxygen equipment. Liquid
  oxygen is very cold and causes cryogenic "burns".
  The eyes and lungs are especially sensitive to
  the cold vapors. Protect eyes and skin from
  exposure to low temperature materials with safety
  goggles, loose fitting gloves and protective
  clothing.
• Oxygen is nontoxic, but high concentrations may
  damage the respiratory tract over time.
• Clothing which has absorbed liquid oxygen or
  oxygen gas must be removed and aired out for at
  least 30 minutes before it is considered safe to
  wear.

Technical specification
Production
Safety
6
Acetylen
Characteristics

•  Acetylene is a colorless and tasteless gas with
  a garlic-like odor. It is flammable and can be an
  asphyxiant. It is one of the fuel gases used in
  oxy-fuel gas welding, which is any welding
  procedure that combines a fuel gas with oxygen to
  produce a flame. The heat and temperature
  produced by an acetylene flame depend upon the
  amount of oxygen used to burn it. Air-acetylene
  produces a flame temperature of around 4000 F
  (2200 C). This is hot enough to solder aluminum
  work glass, repair radiators and braze plumbing
  fixtures. It is not hot enough to weld steel.
  When acetylene is burned in pure oxygen, the
  flame temperature may be as high as 5730 F
  (3166 C). However, the flame temperature and the
  amount of heat generated (measured as BTUs or
  kilogram-calories) depend upon the ratio of
  oxygen to acetylene used. Acetylene can produce
  carburizing, reducing, neutral and oxidizing
  flames. The specifications for acetylene are
  found in the Compressed Gas Association (CGA)
  Pamphlet G-1.1. Grade D (98.0 percent) is
  considered "commercial" acetylene. The usual
  grade is about 98.8 percent acetylene. This is
  the standard acetylene welding grade. Purified
  acetylene (99.6 percent) is also available.
  Caution Never use acetylene at a regulator
  pressure higher than 15 psig. This fuel gas is
  sensitive to shock and may explode at higher
  regulator pressures. Acetylene is not supplied as
  a liquid for similar safety reasons. The gas is
  dissolved in acetone and supplied in heavy-walled
  cylinders filled with porous mass packing
  material. Purified acetylene (Grade 26) is
  prepared for use in Atomic Absorption
  Spectrophotometers.

Technical specification
Production
Safety
7
Acetylen
Safety Acetylene mixed with air or oxygen in a
confined space will explode when ignited.
Acetylene decomposes explosively if piped at
pressures above 15 psig and exposed to mechanical
shock or ignition source. Acetylene forms
explosive compounds with copper, silver and
mercury. Use steel pipe and fittings and pressure
gauges with steel or stainless steel bourdon
tubes. Copper alloys if used must contain less
than 65 percent copper. Acetylene has a very wide
flammability range in air of 2.5 percent to 81
percent by volume. Also very low energy sparks
such as static electricity can cause ignition and
explosion. Store acetylene cylinder outdoors or
in well-ventilated areas away from hot surfaces
or flammable materials and ignition sources such
as flames or any equipment that can generate a
spark. Cylinders must be stored in an upright
position. Acetylene cylinders should not be
dropped or handled in such a manner as to damage
the filter. Use only cylinders and equipment
especially designated for acetylene. Never
attempt to put acetylene in any other container,
equipment or pipeline at pressures above 15 psig.
This can be done only at filling plants with
proper manifolds, flash arrestors and cylinders
with acetone solvent. Make certain all hardware
is steel or brass with copper content below 65
percent. Also no silver or mercury can be present
where acetylene can react with it. Correct any
leak situations. Leaking cylinders that cannot be
stopped should be placed outdoors and returned
for repair. All electrical equipment must be
explosion-proof. Tools used around acetylene must
be non-sparking (brass or aluminum bronze is
required). Articles of clothing that develop
static charges should not be worn where acetylene
is handled in volume and leakage may be present.
Work in well-ventilated areas. Acetylene is
nontoxic but if it displaces oxygen in the air to
levels below about 19.5 percent it can cause
brain damage and even death. However, acetylene
has a distinctive odor which is readily detected
in low concentrations so that warning is given of
the possible hazard.
Characteristics
Technical specification
Production
Safety
PHYSICAL PROPERTIES PHYSICAL PROPERTIES PHYSICAL PROPERTIES PHYSICAL PROPERTIES PHYSICAL PROPERTIES PHYSICAL PROPERTIES
Specific gravity (air 1) _at_ 60 F (15.6 C) Specific gravity (air 1) _at_ 60 F (15.6 C) 0.906 0.554 1.55 1.476
Vapor pressure at 70 F psig (20 C, kPa) Vapor pressure at 70 F psig (20 C, kPa) 635 (4378) -- 120 (757) 133 (916)
Boiling range F (C) 1 atm Boiling range F (C) 1 atm -84 -259 -44 BP -54 BP
Flame temperature in O2 F (C) Flame temperature in O2 F (C) 5589 (3087) 4600 (2538) 4579 (2526) 5193 (2867)
Latent heat of vaporization at 25 C, Btu/lb, (kJ/kg) Latent heat of vaporization at 25 C, Btu/lb, (kJ/kg) -- -- 184 (428) 188 (437)
Total heating value (after vaporization) Btu/lb (kJ/kg) Total heating value (after vaporization) Btu/lb (kJ/kg) 21,500 (50,000) 23,900 (56,000) 21,800 (51,000) 21,100 (49,000)
Btu/ft3 (MJ/m3) 2404(90) 1470(55) 900-1000(34-37) 2498(93) 2371(88)
8
Safety Acetylene mixed with air or oxygen in a
confined space will explode when ignited.
Acetylene decomposes explosively if piped at
pressures above 15 psig and exposed to mechanical
shock or ignition source. Acetylene forms
explosive compounds with copper, silver and
mercury. Use steel pipe and fittings and pressure
gauges with steel or stainless steel bourdon
tubes. Copper alloys if used must contain less
than 65 percent copper. Acetylene has a very wide
flammability range in air of 2.5 percent to 81
percent by volume. Also very low energy sparks
such as static electricity can cause ignition and
explosion. Store acetylene cylinder outdoors or
in well-ventilated areas away from hot surfaces
or flammable materials and ignition sources such
as flames or any equipment that can generate a
spark. Cylinders must be stored in an upright
position. Acetylene cylinders should not be
dropped or handled in such a manner as to damage
the filter. Use only cylinders and equipment
especially designated for acetylene. Never
attempt to put acetylene in any other container,
equipment or pipeline at pressures above 15 psig.
This can be done only at filling plants with
proper manifolds, flash arrestors and cylinders
with acetone solvent. Make certain all hardware
is steel or brass with copper content below 65
percent. Also no silver or mercury can be present
where acetylene can react with it. Correct any
leak situations. Leaking cylinders that cannot be
stopped should be placed outdoors and returned
for repair. All electrical equipment must be
explosion-proof. Tools used around acetylene must
be non-sparking (brass or aluminum bronze is
required). Articles of clothing that develop
static charges should not be worn where acetylene
is handled in volume and leakage may be present.
Work in well-ventilated areas. Acetylene is
nontoxic but if it displaces oxygen in the air to
levels below about 19.5 percent it can cause
brain damage and even death. However, acetylene
has a distinctive odor which is readily detected
in low concentrations so that warning is given of
the possible hazard.