Mental hospital history on record? Please Answer?

When I was 14, I was admitted into a childrens mental hospital. It was all voluntary, No law enforcement was involved or court order. My question is. Is it put on my permanent record? When you turn 18 wouldn't that be sealed? For example when someone wants to get a job or join the military, Would this information be shown on background checks? If you don't tell your employer about this can they find out?