DEFINITION :

Petroleum Hydrocarbon Solvents are volatile fractions derived from petroleum and are composed essentially of paraffinic, natphthenic and aromatic hydrocarbons in varying proportions.

Hydrocarbon solvents are usually clear and water-white, apart from a few exceptions which are yellowish to brown in colour. While virtually immiscible with water, they are miscible with a wide range of other industrial solvents.

NOMENCLATURE

Hydrocarbon solvents are generally classified by the temperatures at which they start and finish boiling i.e. by their boiling ranges, and can be divided into four main groups:

SPECIAL BOILING POINT SPIRITS (S.B.P.s)

S.B.P.s may be narrow or wide boiling fractions, generally within the range 35⁰C and 160⁰C. They are fractionally distilled to specially selected distillation ranges and subsequently refined to enable a suitable grade to be chosen for any particular industrial purpose.

They are fractions intermediate between motor spirit and kerosine, and boil within the range 140⁰C - 225⁰C. They are also known as Mineral Turpentine Spirits, Petroleum Spirits, etc.

KEROSENE TYPE SOLVENTS

They have boiling range between 160⁰C to 300⁰C and have final boiling points above 220⁰C.

Aromex, falls within this classification and is produced at the Digboi refinery of IOC.

PURE AROMATICS

They are pure hydrocarbon compound and boil off at one temperature. Products like Benzene, Toluene and Xylene fall under this category. 

SBP SPIRITS (55/115)

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1. RUBBER INDUSTRY

The main use of SBP spirit 55/115 is in the rubber industry, particularly in tyre manufacture, where successive layers of rubber and rubberised fabric are built up. The brief application of SBP, between each layer, results in thickening of the surfaces and satisfactory adhesion until the layers are eventually welded together by vulcanisation. The time of contact should not be too lond and the solvency not goo great, and hence volatile, low aromatic SBPs, such as SBP 55/155, are used. RApid solvent evaporation is also necessary to avoid slowing down the rate of work.

It is also used fo preparation of certain rubber mixes, cements and adhesives.

2. As a thinner for varnish, paint and printing ink formulations when quick drying is required.

3. As a diluent for lacquers, enamels, high-grade leather dopes and as a solvent for processing polishes, cleaning and water - proofing compounds

4. As a fuel for gas generation plants.

5. As a solvent for dry cleaning, where quick drying time and reduced residual odour are desired.

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1. By far the main outlet for this product is in the manufacture of surface coating, i.e. paints, varnishes and lacquers. Surface coating sare used for the protection and /or decoration of surfaces and are usually applied as liquids eventually hardening to give a solid film.

The important properties of a solvent which influence its suitability for surface coatings are solvency or solvent power and volatility. Solvency is  mainly a function of the hydrocarbon types presents; aromatics having the greatest solvent power followed by naphthenes and then paraffins.

2. Dry Cleaning

The principle of dry cleaning is simple; most solid dirt is held in the garment by a thin film of grease. The function of the cleaning solvent is to dissolve this grease, the dirt can then be removed fairly easily by mechanical means in machines, where the clothes are agitated whiles immersed in solvent. A solvent recovery system is usually incorporated.