Solvent fumes

Solvent/fume leak- Maintain integrity of gaskets and seals age from casing, gaskets compatible with process materials joints resulting in loss of heck mating faces for corrosion/unevenness, containment. particularly on clad components ... 

After a chromatogram has been developed the TLC plate is removed from the developing chamber and the status quo is fixed by removing the mobile phase remaining in the layer as quickly as possible. This is properly performed in the fume cupboard so as not to contaminate the laboratory with solvent fumes. If possible the TLC plate should be laid horizontally because then as the mobile phase evaporates the separated substances will migrate evenly to the surface where they can be the more readily detected. A fan or hair dryer (hot or cold air stream)... 

When the highest resistance to corrosion and solvent fumes is needed, catalyzed paints are the answer. These come in two parts a clear or colored base finish and a catalyst. Since their pot life is limited (typically eight hours), they must be mixed just prior to use. Brochures with information on their chemical resistance can be obtained from companies that sell industrial finishes. Since the resistance to different chemicals varies from brand to brand, a planner should study several types to find one that will best suit the particular application. These finishes are of the high gloss type. For highest chemical resistance to fumes, a coat of clear finish should be applied on top of the colored one. While the vehicle in the finish is very resistant, the pigments may not be and therefore could discolor. 

Spray cleaning of parts with solvent, using an airless gun similar to a paint sprayer, is also practiced. Spray cleaning is typically performed in a ventilated fume hood so as to protect the worker from solvent fumes. In addition to the fume hood, an emissions control system is often required. Many local air quality agencies prohibit the spray cleaning of parts with solvent or require an appropriate emission control system to be in place. 

Trichlorosilane is a colourless transparent liquid (the boiling point is 31.8°C, the density is 1.38 g/cm3). It dissolves well in organic solvents, fumes in air and is very sensitive to moisture in air. It is combustible and forms an explosive mixture with air. 

During the mixing process, tremendous amounts of solvent fumes are likely to be given off along with condensed water from the air. Therefore, the original preparation of a slush bath should be done in a fume hood. Once the slush bath begins to reach equilibrium, the amount of vapors leaving the Dewar decreases and it is safe to remove the bath from the fume hood. 

The use of paint stripper may lead to damage to the skin from both the sodium hydroxide (caustic soda) and the solvent, methylene chloride. Another, more serious hazard from the paint stripper is the danger of using it in a confined space and inhaling the solvent fumes. Apart from the... 

As we saw in our discussion of redox reactions, combustion reactions can travel through the gas phase quite rapidly. Solvent fumes, likewise, can be quite flammable, which is why they should be used away from any sparks or open flame and in a well-ventilated space. The liquid solvent... 

An example of air pollution in a confined space is the air in an airplane. The air in commercial airplanes contains reduced levels of oxygen, increased levels of carbon monoxide, carbon dioxide, ozone, volatile organic compounds and particulate matter. These contaminants have led to cockpit crew, cabin crew, and passenger complaints of headache, fatigue, fever, and respiratory difficulties. Another example of confined space air pollution is the release of solvent fumes when interior walls of buildings with inadequate air circulation are painted. ... 

The hazards may range from those with severe immediate impact, such as acute overexposure to solvent fumes, or drying of the skin from solvent exposure to very subtle health effects such as sensitizations from isocyanates. Long term, or chronic, effects such as cancer from selected solvents or pigments must also be included. 

Today, however, there are other criteria than solvent power and volatility which need to be considered. Regulations covering the exposure to solvent vapours of makers of the product and its users are much stricter than in times past and, as knowledge of the potential dangers improve, are likely to become even stricter. No longer is it possible to protect the makers and users by improved ventilation to draw the solvent fumes away and to discharge them, heavily diluted, into the atmosphere. 

To protect operators from solvent fumes while drum emptying, the use of a vacuum receiver is effective. If a centrifugal pump is used, spillage from its suction... 

There are some circumstances where permanent ventilation cannot be installed to remove solvent fumes and the only method to make an atmosphere fit to breathe is by providing so much ventilation air that the solvent vapours will be diluted to a safe level. This will not necessarily produce pleasant working conditions since safe dilution is based on TLV and vapour pressure. A solvent (e.g. pyridine) with a very low odoiu threshold may have a nasty smell at a concentration well below its TLV as the values for odour safety factor indicate. 

The primary modes of uptake of solvents by the body ate inhalation and by absorption through the skin. The rate of absorption by inhalation is affected by a number of factors, some due to the properties of the material and the interaction of the solvent vapors with the lungs, and some due to other factors such as the concentration of the solvent fumes in air, the duration of the ejqiosure, and the level of exertion at the time of exposure by the exposed individual. The rate of intake is significantly increased by elevated levels of physical activity. 

In operation, an exhaust blower, mounted external to the degreaser, pulls vapor from the top of the freeboard zone, through the lip vents, and out of the work area. Presumably, the removed vapor is rich in solvent fumes. 

So the concerns about water intrusion with cold cleaning solvents are different and significantly less than the same with halogenated cleaning solvents. Finally, per the specifications noted in Footnote 78 and their outcomes as noted in Table 1.14, the undiluted solvent fumes emanating above the cooling coils contain no more solvent than 25% of the LEL and so can t be ignited. 

The list of process steps in Tables 2.6 through 2.10 provides examples of how a vessel should be purged (Box 2.7)°° of solvent fumes when vacuum capability is available. Note that these processes include sequential steps where the work chamber, filled with a solvent atmosphere (1) has 99.87% of that atmosphere removed by vacuum (2) is then filled with air (or any inert gas such as nitrogen), and that atmosphere is also removed by vacuum and (3) finally is filled with dry air before opening. 

That environment is usually nitrogen gas, often heated to enhance the rate of vaporization. The gas stream is generally not recycled — thus maximizing the driving force for vaporization — but is treated to remove solvent fumes by a bed of activated carbon (Chapter 4). 

Figure 4.11 Emission, Collection, and Treatment of Solvent Fumes...

It may be that not all of the locations noted above continuously produce solvent fumes. So to conserve resources (solvent, adsorbent bed life, and user attention), sophisticated users are likely to find it economically attractive to couple the air amplifier to an on-line explo-simeter — so that the air amplifier can only extract air when it is polluted with solvent. 

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