Sihi Liquid Ring Vacuum Pump. Model: LPHB3704. Vacuum capacity: 20 in. Hg @ 25 cfm. Displacement capacity: 4 gpm. The SIHI LPH series liquid ring vacuum pump is reliable pump that can be used in a variety of applications. The vacuum pumps have one moving part, the impeller and shaft assembly. Inlets/outlets: (2) 1-1/2 in. dia. flanged port. Overall dimensions: 39 in. L x 12-1/2 in. W x 15-1/2 in. H.