With an array of sampling tubes like this, a detailed guide is a critical element of blood bank safety and effectiveness.

A blood bank is no place for mistakes.  Improper sampling, improper routing, improper storage can all have severe—even life-endangering—consequences.  So if you work in a blood bank you’d want a guide to follow, a document that would help minimize the chance for error.  If you work at the University of Michigan, you’re in luck.  They have an online faq that spells out which tubes should be used to draw samples for typing and screening, what size needles should be used for transfusions, and how long red blood cells and plasma can be stored outside of a blood bank refrigerator.  By the way, the answer to that last is 30 minutes.