First, the extinguisher valve is removed and the threads and interior of the cylinder are checked for corrosion, pitting, and any other abnormalities. [29 CFR 1910.157(f)(3)] If the cylinder passes the visual inspection, it is placed into a steel chamber, which is then filled with water at normal pressure.
Updated April 17, 2017. The earliest dated printed book known is the Diamond Sutra, printed in China in 868 CE. However, it is suspected that book printing may have occurred long before this date. In 1041, movable clay type was first invented in China.
Johann Gutenberg, inventor of Europeâs first printing press in the 1450âs, unexpectedly created a demand for knowledge and news. Impressively, over 50 years after his invention, âan estimated 500,000 books were in circulation, printed on about 1,000 presses across the continentâ (Nelson, 1998, p. 1).