Internal gear pump Model HD81ER-1U33B - P/N 2581 HD: Heavy duty pump, Complete with motor on a common baseplate through flexible coupling 81: Pump size DN 80 - 3 " E: Suction/Discharge connection in-line M: Sealing with single mechanical shaft seal combined with a ball bearing as main bearing R: Safety valve, single acting for protection against excess pressure 1: Casing & cover: GG-25, Rotor/Idler: GG-25, Shaft: St.60.2 U: Idler bearing and main bearing lubricated by pump medium 3: Idler bush: carbon, idler pin: Hardened 16 MnCr5 3: Bearing bush: Carbon, Shaft: St.60.2 B: Shaft seal: Teflon-impregnated non-asbestos Packing