How to add number of Hours to a Date Field

I am back with a very
basic requirement which might looks very easy, but the solution might not
be that easy to implement.



Requirement:

I have a Service
Request form applet where I have following fields exposed on the UI:



Severity - LOV
field values: a) 1-Critical b) 2-High c) 3-Medium d) 4-Low
Commit Date - Date
Time field


Depending upon the
Severity, being set by the user, system