Worked grease

Three important precautions are needed when working with pipets and volumetric flasks. First, the volume delivered by a pipet or contained by a volumetric flask assumes that the glassware is clean. Dirt and grease on the inner glass surface prevents liquids from draining evenly, leaving droplets of the liquid on the container s walls. For a pipet this means that the delivered volume is less than the calibrated volume, whereas drops of liquid above the calibration mark mean that a volumetric flask contains more than its calibrated volume. Commercially available cleaning solutions can be used to clean pipets and volumetric flasks. 

In addition, vanillin was among the three or four aroma chemicals that helped perfumers of the past to imagine a new generation of fragrance combinations. The work done in organic chemistry by chemical companies has helped perfumers who had been restrained in their creation by the avadabihty of raw materials, which include natural oils and extracts made by the enfleurage process, ie, the property of perfumes to stick on fat and greases. Those extracts were weak, flat, and unpleasant. 

Skim off oil and grease scum from the surface of the bath every day or more frequently, depending upon the amount of work being handled. 

Silicone greases do, however, have uses in extrusion for coating dies etc., to facilitate stripping down. Greases have also found uses in the laboratory for lubricating stop cocks and for high-vacuum work. 

Fig. 35. OSEE response and peel strength of NBR rubber on steel for HD2 grease (data from Ref. [162]) and silicone release agent contamination (data from R.L. Cause, unpublished work and Ref. [10]). The HD2 grease is slightly photoemitting so the OSEE signal does not decrease to zero at high contamination levels.

The grease X is sub-divided into consistency numbers, in accordance with the system proposed by the National Lubricating Grease Institute (NLGI) of the USA. These consistency numbers are related to the worked penetration ranges of the greases as follows ... 

Fully charge the bearing itself with grease ensuring that it is worked around and between the rolling elements. 

To check the efficacy of grease removal, the alkali solution is rinsed away or neutralised by dipping in dilute acid. If, after removal from the acid, the draining metal surface remains wetted evenly all over for 30-60 s (or until it dries by evaporation), hydrophobic soils have been removed. Traces of grease cause the surface to de-wet, and surface tension draws the water into separate droplets. This is the water-break test. Traces of grease which remain when the work is plated do not prevent electrodeposition, but are detrimental to adhesion and corrosion resistance. 

Non-polar hydrocarbon-type liquid phases, e.g. paraffin oil(Nujol), squalane, Apiezon L grease and silicone-gum rubber the latter is used for high-temperature work (upper limit 400°C). 

Nonaqueous solvent degreasers tend to work as cold degreasers, but where considerable quantities of grease must be removed, aqueous-based emulsifying degreasers are employed, and these work best in hot water or steam solution. 

With the recent emphasis upon the analysis of trace metals and organic materials, particularly possible pollutants, it has become obvious that cleaner working areas are necessary. The winch room, with its assorted greases and oils,... 

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