Jordan McClurkin hit a blistering century to ease the pressure on injury ravaged Instonians and increase Armagh's isolation at the foot of the Premier table.
McClurkin savaged the Armagh attack on his way to 109 from just 58 deliveries as he and James Metcalfe (52) shared an opening stand of 167.
Andrew White was also in the runs, making 57 as Instonians scored 281 - Michael Hoey taking three wickest.
Armagh's chase never materialised with Getkate and Magee taking three wickets apiece.
South African professional Shadley van Schalkwyck offered the only resistance hitting 81 in their total of 139.
The other 10 Armagh batters scored a combined 47 on a day to forget.
With five games remaining they will have to win at least three to give themselves a chance of avoiding an immediate return to the second tier.
SCORECARD AND TABLE