The image below is a schematic flow diagram of a typical oil refinery that depicts the various unit processes and the flow of intermediate product streams that occurs between the inlet crude oil feedstock and the final end products.
In order to check-in into a hotel, the person must be 21 years old.  If the person is younger than 21, then a parent or guardian can  give permission for them to check-in. 1 person found this useful.
Anyone planning to visit a casino should note that although you only need to be 18 to gamble, you must be 21 years old in order to enter a bar. Many of the casinos are also bars which serve alcohol throughout, and as such minors will not be allowed in.