Break test

When a quantitative estimate of residual soil is not called for and the suitabiUty of a metal surface for further finishing needs to be assessed, the water-break test is used. The term water-break refers to the behavior of a water film on a smooth greasy surface. When the film becomes sufficiently thin by drainage, it suddenly breaks into islands or droplets between which the surface appears dry. On the other hand, when a film drains from a clean water-wettable, nongreasy surface, it becomes progressively thinner and finally disappears by evaporation without ever breaking into droplets. Such a surface is said to be free from water-break. 

To inspect for contaminants, a water break test is frequently employed. Water, being a polar molecule, will wet a high-energy surface (contact angle near 180 ), such as a clean metal oxide, but will bead-up on a low-energy surface characteristic of most organic materials. If the water flows uniformly over the entire surface, the surface can be assumed to clean, but if it beads-up or does not wet an area, that area probably has an organic contaminant that will require the part be re-processed. 

Bnich-kupfer, n. scrap copper, -last, /. breaking load, -metall, n. broken metal, scrap metal, -modul, m. modulus of rupture, -probe, /. breaking test, breakdown test, -punkt, m. breaking point, -riss, m. (Meial.) failure crack, -silber, n. broken silver, scrap silver, -spaonung,/. breaking stress tensile strength, -stein, m. quarry stone broken stone, -stelle,/. broken place, place of fracture. -strich, m. (Math.) fraction stroke (between numerator and denominator), -stiick, n. fragment shred, -stiicke, pi. debris scrap, -teil, m. fraction, -zahl, /. fractional number. 

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. 

Fig. 7.3. No. 2 break test. (The position of the upper plate is shown by the broken lines.)...

In the No. 2 break test the explosive is fired almost unconfined. Under these conditions weak coal mining explosives detonate only partially and the probability of ignition of the gas mixture is reduced. Measurement of... 

Five shots are fired of the maximum permitted charge weight of explosive into methane/air mixture in Break test I. No ignitions may occur. 

Break Test II uses a gas mixture of 3-60% propane with air and nitrogen, which is more easily ignited than methane/air. Preliminary shots determine the most hazardous charge of explosive not exceeding 227 g. Twenty-six shots are then fired at this weight and not more than thirteen ignitions may occur. 

Five shots of 30-5 cm length and 3-7 cm diameter are fired in methane/air in Break Test III. No ignitions may occur. 

Den Fall, daB durch Risse und Spalten eine ganze Ladesaule in Kontakt mit der gasfuhrenden Atmosphare tritt, illustrieren der briti-sche Break-Test und der polnische Schlitzmorser ... 

Water-break test, 9 782 Water carriers, 25 327 liability of, 25 336... 

BP = russian abbreviation name for -+ shaped charges BPZ russian denomination for hollow charges with incendiary effect branchement en parallele = parallel connection 243 break 40 break test 250 breech 41... 

Break Test 3 consists of a break occurring at the end of a shot-hole. This is simulated by a cannon fired with the mouth in close proximity to a steel plate. 

Break Test I consists of a shot-hole in which a break occurred across the hole in the middle of the explosive charge. It is simulated by placing a train of explosive across the gap between two steel plates in a test gallery. 

Break Test 2 consists of a break parallel to the shot-hole in such a way that half of the shot-hole is in one piece of rock and the remainder of the explosive in the space between the rocks. It is simulated by two parallel plates of which the lower is grooved as a bore-hole — Fig. 96. 

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