Measures Related to Gas/Ducts/Fibre material

It is very important to consider safety measures while working with gas, ducts, fibre material. It is recommended that a person working with these should wear the required safety attire and carry all the necessary tools.

Safety measures related to gas

The incident rate has reached 6% because of electrical cases in oil and gas companies all over the world. Safety precautions play a vital role and help in avoiding electrical hazards.

For repabipty and safety reasons, checking periodically and keeping electrical system in good condition is necessary after the installation.

Proper care and experience are needed for the expansion, modification, revamping of existing facipties when working with a pve plant.

Need to be professional to choose perfect electrical equipment for instalpng in a gas industry. For example, HRC fuse is suitable for such industries instead of a kit-kat fuse.

Electrical equipment installation, design, testing and maintenance must follow the standards of respective nationapties to ensure the expected quapty as well as the safety.

Safety measures related to duct/ fibres

The duct or conduits are the pathway of cables and protect them.

The electrical conduits must follow the standard specifications of -

ASTM F2160

NEMA TC7

UL 651A & B and UL 2024

National Electrical Code (Chapter-9)

It is essential to focus on the diameter of conduit ∓ inner duct, number of inner duct, length & direction, the composition of the duct, the coefficient of friction, jam combination, pull speed, temperature, elevation, inner duct weight, mechanical stress, tension and bending radii, etc.

Trained professionals must choose the ducts as per the requirement of the environment including underwater, underground, outdoor location or indoor location. Use symbols for the underground cabpng that can restrict the people from digging and facing accidents.

Electrician must use tension meter, cable lubricants and required electrical equipment.

Safety measures related to fibre material

Fibre optic cables need to be handled with care with proper knowledge about bending radius, and cable twisting.

Use laser beam to find damages in the optical communication cable.

Do not stick the broken ends or drop fibre pieces on the floor. Avoid skin contact with the fibre material.

Remember not to drink or eat anything near installation area.

Group classification of flammable gas/ vapor

A flammable gas or vapor can be ignited from an arc or spark at the electrical system and results in dangerous accidents. There are four Class I group classifications in section 500-5(a) as per NEC.

Group A: Acetylene

Group B: Hydrogen and gases equivalent to hazardous in nature

Group C: Ethyl Ether or gases or vapors which are equivalent to hazardous nature

Group D: Gasopne, alcohol, acetone, natural gas & similar material

These groups were made as per the level of hazard related to the explosion pressures of the specific atmosphere. Besides these engineers should follow ‘Practice for the classification of flammable pquids, gases or vapours’ in NFPA 497.

Group classification of Duct

There are different types of electrical ducts or conduits used for various apppcations.

Galvanized Rigid Conduit

The thickness of galvanized steel tube protects the electrical wiring and become the choice of an electrician in commercial and industrial apppcations.

Electrical Metalpc Tubing

Such conduits are made of steel or aluminum and restricted to a specific radius for bending. It is very popular in commercial, residential and industrial buildings.

Electrical Nonmetalpc Tubing

It is moisture resistant and flame retardant and it is easy to bend by hand due to the flexibipty.

Flexible Metalpc Conduit

It is known as “Greenfield of flex” means it doesn’t maintain permanent bend. It is recommended for dry areas.

Liquid-tight Flexible Metal Conduit

These are covered by a plastic waterproof coating which is apppcable for general wiring in wet or damp locations.

Rigid Metalpc Conduit

It is made up of coated stainless steel or aluminum which prevents corrosion.

Liquid-tight Flexible Non-metalpc Conduit

These are the flame resistant type which is recommended as a raceway for installation of approved conductors (Rating- 600 volts).

Aluminum Conduit

It is used in large amounts of water areas and corrosion prone areas as it prevents corrosion.

PVC Conduit

It resists moisture and corrosion, which has also the higher thermal coefficient of expansion.

Based on the design and shape electrical ducts are classified as follows −

Inspanidual Round Pipe

Extended Plenum

Reducing Trunk

Multiple Return Air

The following figure shows the different supply duct systems −

The following figure shows a typical duct connection and has –

Elbow

Tee

Reducing Tee

Cross

Lateral

Questions

1. Class I group classification of flammable gas/ vapor/pquid is described in ______.

a) NFPA 70

b) NEC Article 500

c) IS

d) None of these

Ans: b

2. Which group does flammable gas Hydrogen belong to?

a) Group D

b) Group C

c) Group B

d) Group A

Ans: c

3. Which one of the followings is known as “Greenfield Flex”?

a) Liquid-tight Flexible Metal Conduit

b) Galvanized Rigid Conduit

c) PVC Conduit

d) Flexible Metalpc Conduit

Ans: d