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.
Historians have placed it sometime between 1473 and 1475 at a workshop in Bruges. Sotheby's copy, one of just 18 surviving from that first printing, features annotations in the book's margins written by multiple centuries worth of readers. It is the first copy to appear for auction in over ten years. Having last been purchased in 1948 for 15,000 GBP, or $25,727, it sold earlier today for a record 1,082,500 GBP ($1,823,363).