Scratch mark

Along with the sounds, evidence and signs of cavitation, there is a broad range of other information and signals available to the maintenance mechanic. Almost all mechanics have seen the gouge and scratch marks, and signs of heat on the pump when disassembled in the shop. Sadly, most mechanics are never trained to interpret these marks. 

The scratch marks on the circumference of these close tolerance rotary parts will correspond to. scratch marks on close tolerance stationary parts at approximately 60 around the volute from the cutwater. These marks will be vi.sible on the back plate with open impellers, or on the wear rings of pumps with enclosed impellers, or the ID bore of the restriction bushing at the bottom of the seal chamber where the shaft pa.sses through, or the ID of the seal chamber bore at the back end of the mechanical seal (Figure 9-6 and Figure 9-7, next page). 

The basic difference between a bent shaft and a deflected shaft is the following. A bent shaft spinning inside close tolerances leaves a scratch mark around the eireumferenee of stationary elements corresponding to a damaged spot on the shaft. A deflected shaft. spinning within close... 

Artifacts introduced through sample preparation are common materials these may be bits of facial tissue, wax, epithelial cells, hair, or dried stain, all inadvertently introduced by the microscopist. Detergent residues on so-called precleaned microscope slides and broken glass are common artifacts, as are knife marks and chatter marks from sectioning with a faulty blade, or scratch marks from grinding and polishing. 

The American Aeronautical Material Specification AMS 2480 A calls for 150h salt-spray test without rusting extending more than 0-125 in (3-175 mm) on either side of scratch marks, using a black enamel finish for the phosphate coating. 

Rub one solid onto the surface of another. Rank the relative hardness of each solid on a scale of 1 to 5. A solid that receives no scratch marks when rubbed by the other four is the hardest (5). A solid that can be scratched by the other four is the softest (1). 

The lack of scratch marks will decrease the incidence of turbulent flow, as well as ensuring that the fractal area of the electrode is essentially the same as the electrochemical area. 

Fine abrasive will remove the scratch marks formed by the coarser particles, i.e. decreasing the fractal area of the electrode (see Section 5.1.2). 

The relationship between the hardness of a surface and its resistance to scratching is evident (and, by analogy, polyester laminates can be scratched more easily than melamine)—but scratch resistance is influenced also by surface finish and colour. In general, scuff and scratch marks are more obvious on plane finishes (whether glossy or matt) and on dark colours than on textured finishes and light colours. Figure 62 illustrates this relationship. 

FIGURE 17.41 A large scratch in copper. The left picture shows a rather large scratch that has also marked the Ta between the copper lines. Both pictures show that a scratch marks the copper deeper than the surrounding Ta. 

A convenient apparatus for this transfer from the ampul is shown in Fig. 116. The frozen ampul, the neck of which is scored by a scratch mark, is attached to the frit arm by thick-walled rubber tubing, and the complete apparatus is evacuated. The scored portion of the neck extends inside the wider-bore frit arm. The apparatus is filled with nitrogen, and the ampul is allowed to warm until the methyltitanium trihalide has melted and dissolved in its oc-... 

Dip the diamond tool in turpentine before each cut. Scratch and break one line at a time. Make only one scratch mark. Find out the correct angle and pressure for the tool. Use new glass. Chip off small pieces of waste with old pliers or side-cutters. 

Pruritus is accompanied by scratch marks (s. pp 85, 232), which the tormented patient inflicts, often with great intensity, on all accessible parts of the body (f as long as it bleeds, it doesn t itch any more ). Fresh scratch marks on the skin alternating with older, blood-encrusted sites are characteristic of the body surface of a patient suffering from chronic cholestasis, such as primary biliary cholangitis, (s. fig. 13.3)... 

Fig. 13.3 Scratch marks resulting from pruritus in recurrent intrahepatic cholestasis...

Thrust the dispenser into a can of fruit paste and suck up paste to the scratch mark on the glass tube. Then wipe the glass tube with afacial tissue, insert it into a 25 x 150-mm test tube, and blow out the paste onto the bottom of the receiver. Wash the dispenser tube clean with water and leave it upright to drain for the next user. 

Mechanical activity of boring organisms is also reflected in scratch marks (e.g. Warme, 1975). In general, boring patterns are determined both by the specificity of the boring organism as well as by the particular nature of the bored substrate, and both factors need to be considered in their interpretation (Golubic and Schneider, 1972). 

Glass can be cut by making a single scratch mark on it with a file or knife. The scratch is moistened with a drop of saliva, the scratch mark placed upward, and the tubing pulled apart with a slight downward bending motion. The bottom photograph in... 

Keep the tank cover on tightly, particularly if you have scratched the coating at the 12 cm mark. This keeps the solvent from evaporating at the scratch mark and stops the capillary action. As a result, the Redoes not change. 

The sample is spotted 2 cm in and up from one comer, and the first standards are spotted to the right of the vertical scratch mark, usually 1 cm apart and 2 cm from the bottom of the plate. The plate is developed as usual and, in this case, produces the separation indicated by the O s. 

What is the advantage of making a scratch mark in the coating 10-12 cm above the spot ... 

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