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.
Around 1100 A.D. paper arrived in Northern Africa and by 1150 A.D. it arrived to Spain as a result of the crusades and established the first paper industry in Europe. In 1453 A.D. Johann Gutenberg invents the printing press. The first paper industry in the North America was built in Philadelphia in 1690.