Hot Melt Hot Melt adhesives are thermoplastic polymers that soften (become less viscous) when heated. Applied by a local system that melts the adhesive and adjusts pump speed to match the speed of the converting machine. 1224A Cast iron Jacketed for steam/oil prior to pump startup O-Pro® Cartridge seal to minimize leakage Capacities to 400 GPM 224A Cast iron Jacketed for steam/oil heating prior to pump startup Capacities to 500 GPM SG Ductile Iron Compact Installation Capacities to 190 GPM