Page 73 - CITS - Welder - Trade Theory

WELDER - CITS

4 Never put a naked light of any kind or any other source of ignition into or near the carbide container.
5 Carbide drums should be opened with tools which will not produce sparks. Use a brass chisel and hammer.
6 Fire break out in a carbide storage room must be extinguished with Co2 fire extinguisher or dry Sand and not
with water.
7 After taking out the Cac2 from a drum, it mist be closed and made air light immediately.
8 Preserve carbide in kerosene oil in case of emergency.
9 The person, handling Cac2, must wear rubber gloves.
10 Empty carbide drums must be filled completely with water before disposing of.
11 License must be required to store CoC2.
12 Notice should given in CaC2 Store.

Acetylene gas properties , Manufacturing method Acetylene
gas purifier

Objectives : At the end of this lesson you shall be able to
• explain the composition and properties of acetylene gas
• explain the acetylene manufacturing method.
• explain the working principle of the types of acetylene generators
• explain the acetylene gas purifier.

Introduction
Acetylene is a fuel gas, which produces a very high temperature flame with the help of oxygen, because it has
more amount of carbon (92.3%) than any other fuel gas. The temperature of oxy-acetylene flame is 3100°c
- 3300°c.
Composition of acetylene gas: Acetylene is composed of:
- carbon 92.3% (24 parts)
- hydrogen 7.7% (2 parts)
Its chemical symbol is C2 H2 which shows that two atoms of carbon are combined with two atoms of hydrogen.
Properties of acetylene gas: It is a colourless gas, lighter than air. It has a specific gravity of 0.9056 as compared
with air. It is highly inflammable and burns with a brilliant flame. It is slightly soluble in water and alcohol. Impure
acetylene has pungent (garlic like) odour. It can be easily detected by its peculiar smell. Acetylene dissolves in
acetone liquid
Impure acetylene reacts with copper and forms an explosive compound called copper acetylene. therefore,
copper should not be used for acetylene pipeline. Acetylene gas can cause suffocation if mixed 40% or more in
air. Acetylene mixed with air becomes explosive on ignition. It is unstable and unsafe when compressed to high
pressure i.e. its safe storage pressure in free state is fixed as 1 kg/cm2. The normal temperature pressure (N.T.P)
I 1.091 kg/cm2.The normal temperature is 20°C and the normal pressure 760mm of mercury or 1 kg/cm2. It
can be dissolved in liquid acetone. at high pressure. One volume of liquid acetone can dissolve 25 volumes of
acetylene under N.T.P. It can dissolve 25X15=375 volume of acetylene cylinder if it is dissolved with a pressure of
15kg/cm2 pressure. In an acetylene cylinder it is dissolved acetylene. For complete combustion one volume unit
of acetylene requires two and a half volume units of oxygen.
Composition of acetylene: Acetylene is a fuel gas composed of: carbon 92.3% and Hydrogen 7.7% Its chemical
symbol is C2 H2.
Principle of acetylene gas generation: It is the product of chemical reaction between calcium carbide and
water. When water is added to calcium carbide it reacts and produces acetylene gas and calcium hydroxide
(slakedlime).Calcium carbide is composed of calcium and carbon. Water is Composed of hydrogen and oxygen.
When calcium carbide is allowed to react with water the carbon of the calcium carbide combines with the
hydrogen of water forming acetylene gas. calcium combines with oxygen and hydrogen in water to form slaked
lime (Calcium hydroxide).

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CITS : C G & M - Welder - Lesson 14-26 CITS : C G & M - Welder - Lesson 14-26