Sussex added 61 in their remaining five overs to compile their highest total in the competition. They then dismissed Ireland for 80 in 33.3 overs.
Kyle McCallen was top scorer with 17 while Paul Jarvis and Ed Giddins each took three wickets. Ireland's misery started as early as the second ball of their innings when the captain, Justin Benson, who played in the 1992 final for Leicestershire, was caught at slip without scoring.
Jarvis, in a hostile opening spell, added the wickets of Andy Patterson and Angus Dunlop in the space of four balls to reduce Ireland to 15 for 3, and he finished with 3 for 22.
When McCallen was leg before to Vasbert Drakes in the 12th over, Ireland's debacle at Hove in 1985, when they were shot out for 39, looked like being repeated.
Two more wickets fell before they passed that target, but it needed a ninth-wicket stand of 16 between the opening bowlers, Ryan Eagleson and Mark Patterson, to take Ireland past their next lowest total of 71. Giddins ended the partnership and, when Danny Law finished the innings in his second over, Eagleson was 15 not out.
At the start of the day, Ian Salisbury made 33, his highest score in the competition, and Derek Heasley took the wicket of Jarvis for two to finish with 4 for 66. Drakes was 30 not out.Reuse content