Kitzmiller gives the 19th Foot and the 28th Foot at Cork in 1830. The only record indexed in the soldiers discharge records and the pensionnrecords (WO97 & WO121) That fits your man is:
WO 97/474/112 PATRICK MURPHY Born CLONFERACKLE, Tyrone Served in 28th Foot Regiment Discharged aged 39 1831-1847
If the 'covering dates' at the end coincide with his discharge, ie., 1847, then this would fit quite well with the age of 35 given in the 1841 census you mention.
However since you say that the birth at Cork was approximately 1830; looking at 1831 the 6th Foot 56th Foot and 69th Foot are at Cork and the following are possibilities:
WO 97/556/90 PATRICK MURPHY Born COOTE HALL, Roscommon Served in 39th Foot Regiment; 6th Foot Regiment; 13th Foot Regiment; 47th Foot Regiment Discharged aged 37 1825-1844
WO 97/607/121 PATRICK MURPHY Born KILENMACK, Wexford Served in 46th Foot Regiment; 56th Foot Regiment; 89th Foot Regiment; 11th Foot Regiment Discharged aged 38 1829-1847
Maybe one of these will ring a bell. You can look through the rest at:
http://www.catalogue.nationalarchives.gov.uk/searchresults.asp?fldResultMarker=81&fldSearchNumber=192449&SearchInit=1