Definitions and Terminology
Bunker "C" Fuel Oil: A heavy residual Fuel oil used by ships, industry, and for large-scale heating installations. In industry, it is often referred to as Grade No. 6 Fuel Oil.
Fuel Gas: Any gas used for heating.
Fuel Oil: Any liquid or liquefiable petroleum product burned for the generation of heat in a furnace or firebox, or for the generation of power in an engine, exclusive of oils with flash point below 38°C (tag closed cup tester) and oils burned in cotton-or-wool-wick burners.
Heating Value of a Fuel: The caloric, thermal, or heating value of a fuel is the total amount of heat generated by the complete combustion of a unit quantity of fuel, expressed as kJ/kg for liquid fuels and MJ/Nm³ for gas fuels.

Liquefied Petroleum Gas (LPG): Light hydrocarbon material, gaseous at atmospheric temperature and pressure, held in the liquid state by pressure to facilitate storage, transport, handling. Commercial liquefied petroleum gas consists of propane, butane, or mixture thereof.
Manufactured Gas: All gases made artificially or as by-products, as distinguished from natural gas; applied particularly to a utility send out.
Mazut: A Russian name for distillation residues used largely as fuel oil; also spelled "masut" or "mazout".
Natural Gas: Naturally occurring mixtures of hydrocarbon gases and vapors, the more important of which are methane, ethane, propane, butane, pentane, and hexane.
Purging: The displacement of one material with another in process equipment, frequently, displacement of hydrocarbon vapor with steam or inert gas.
Refinery Gas: Any form or mixture of gas gathered in refinery from the various Units.
Residual Fuel Oil: Topped crude oil or viscous residuum in refinery operations.

General Classification

Crude oil and its derivatives, by their nature, are considered as potentially hazardous materials. The degree of hazard is essentially characterized by its volatility and flash point. The hazardous materials are classified according to their “Closed Cup Flash Point” indicated hereunder:

Flammable Liquid	Class I	Any liquid which has Flash Point (Low Flash Stock) below 37.8oC (100oF)
Combustible Liquid	Class II	Liquid having Flash Point at or (Intermediate Flash Stock) above 37.8oC (100oF) but below 60oC (140oF)
	Class III (A)	Liquids having Flash Points at or above 60oC (140oF) but below 93oC (200oF)
	Class III (B)	Liquids having Flash Points at or above 93oC (200oF)
Flammable Highly Volatile Liquid		Highly volatile liquids include Butane, Propane, Ethane & Ethylene, LPG, NGL and mixture of such.

Area Classification: In industrial terms areas are classified as Restricted, Hazardous and Unclassified.
Restricted Area: A Restricted Area is that area, in which company exercises a control over all movements, operations & maintenance activities i.e. the areas within the fenced boundaries or open space where company has direct or indirect control for operational reasons.
Entry to a Restricted Area is allowed only by an Access Control Pass, which is to be shown at the Security Check Point. There are also Controlled Areas within restricted area where entrance is obtained by application at the point of entry, even though the applicant may hold an Access Pass.
Hazardous Area: A Hazardous Area is the zone in which a flammable atmosphere may be present during normal operation or under abnormal conditions. Hazardous Areas in the petroleum industry are classified according to the likelihood of a flammable atmosphere being present. A flammable atmosphere has a concentration of flammable gas, vapor, or mist, which is capable of being ignited.
ZONE 0 - A zone in which a flammable atmosphere is present continuously or for long periods (Typically more than 1000 hours/year.)
ZONE 1 - A zone in which a flammable atmosphere is likely to occur in normal operations. (Typically 10 to 1000 hours/year)
ZONE 2 - A zone in which a flammable atmosphere is likely to occur only under abnormal operating conditions. (Typically less than 10 hours/year)
Unclassified Area: An Unclassified Area is the area, which not classified as Zone - 0, Zone-1 or Zone-2. Unclassified Area may not necessarily be considered as Safe. A good engineering judgment should be exercised to assess the hazard prior to using any standard electrical apparatus, conventional machines and industrial equipment.
Work Permit Area: It is a normal practice to consider a Restricted Area as a Hazardous Area for the purpose of access as well as where using any form of ignition source, carrying out any operational & maintenance activity that has potentiality to generate spark / heat / fire / explosion or doing any excavation work and vessel entry activity is strictly prohibited without proper authorization through Work Permit.
Approved Safe Area: Certain area within a restricted area may be designated as an approved safe area, such as approved smoking room, areas designated for pre-fabrication work, parking lot and certain work shops, etc. However such areas are to be clearly marked and regulatory instructions governing their use to be strictly adhered to.
Open Areas: An Area within a Restricted Area may be declared as an Open area where maintenance or construction work is allowed without raising Work Permits except in case of Vessel Entry, Excavation Activity, Electrical Work and Hot Work. The limits of such Open Areas must be clearly defined on the ground by fencing, barriers etc. with suitable control over operational & maintenance activities.