(1) One Used Graco Monarch 5:1 Sanitary Drum Unloader. Air-operated pump unit works-on-demand and does not require special controls to shut pump off when fluid line is shut off. By closing the outlet or dispense valve, the pump will stop until flow is again required. Maximum fluid pressure 600 psi (41 bar, 4.1 MPa) 600 psi (41 bar, 4.1 MPa). Maximum flow @ 60 cpm* 2.5 gpm ( 9.5 lpm) 2.5 gpm ( 9.5 lpm). Maximum flow @ 100 cpm* 4 gpm (15.1 lpm) 4 gpm (15.1 lpm). Viscosity range of package 25,000 to 60,000 cps 60,000 to 100,000. Maximum inlet air pressure 120 psi (8.4 bar, 0.84 MPa) 120 psi (8.4 bar, 0.84 MPa). Plunger diameter 22.5" / 57.1cm