Blood Collection Tube are glass or plastic tubes sealed with a partial vacuum inside by rubber stoppers. Its diameter standard is 13 mm, and the length is 75mm or 100mm. The air pressure inside the tube is negative, less than the normal environment. After inserting the longer needle into the vein, the phlebotomist pushes the tube into the holder so that the shorter needle pierces the stopper. The difference in pressure between the inside of the tube and the vein causes blood to fill the tube ... Read more
