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Handbook of Solvents - George Wypych - ChemTech - Ventech!

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1228 Krzyszt<strong>of</strong> M. Benczek, Joanna Kurpiewska<br />

• degreasing in liquid organic solvents, such as naphtha, petroleum, chlorinated<br />

aliphatic hydrocarbons, etc.<br />

• degreasing in hot vapors <strong>of</strong> halogenated solvents such as, trichloroethylene,<br />

perchloroethylene, fluorochloroethane and so on<br />

• degreasing in alkaline water solutions <strong>of</strong> hydroxides, phosphates, surfactants,<br />

emulsifiers, common inhibitors, etc.<br />

• degreasing in an emulsion <strong>of</strong> organic solvents in water<br />

• degreasing in water steam<br />

• supersonic degreasing in stabilized chlorinated hydrocarbons.<br />

Degreasing process can be conducted automatically in different ways by:<br />

• dipping<br />

• spraying<br />

• using high pressure<br />

• supersonic<br />

• pulsating washing<br />

Process can be conducted in open or enclosed equipment. Manual degreasing is still<br />

very popular but it is very time and labor consuming, expensive, and large amounts <strong>of</strong> solvents<br />

are lost.<br />

18.2.3 SOLVENTS<br />

In metal degreasing these solvents are most frequently used:<br />

• naphtha solvent,<br />

• naphtha anti-corrosive<br />

• 1-butanol,<br />

• 1,1,2-trichloroethylene,<br />

• 1,1,1- trichloroethane,<br />

• extraction naphtha,<br />

• petroleum(mineral) spirits.<br />

18.2.4 IDENTIFICATION OF THE EMITTED COMPOUNDS<br />

In many cases, solvent mixtures are used. Their composition must be identified. Rod<strong>of</strong>os is<br />

one example <strong>of</strong> such solvent used in Poland. Its composition was determined by gas chromatography.<br />

Analyses were performed using a Hewlett-Packard gas chromatograph model<br />

5890 coupled with computerized mass spectrometer instrument, model 5970.<br />

Capillary column 50 m x 0.32 mm i.d., d.f.= 0.52 µm FFAP and helium as a carrier gas<br />

was used at temperature <strong>of</strong> 40 o C. Ions from 20 to 400 amu were counted, delay time was 3.5<br />

min.<br />

Samples were collected by drawing a known volume <strong>of</strong> air through a bubbler containing<br />

1 ml <strong>of</strong> carbon disulfide. Volume <strong>of</strong> the injected sample was 1-5 µl.<br />

Chromatograms are presented in Figure 18.2.1.<br />

18.2.5 EMISSION OF ORGANIC SOLVENTS DURING TECHNOLOGICAL<br />

PROCESSES<br />

The concentration <strong>of</strong> substances emitted to the air during the degreasing processes reached<br />

the steady-state constant value:<br />

C = E/q [18.2.1]

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