GB1352507A - Priming of rotadynamic pumps - Google Patents

Abstract

1352507 Centrifugal pumps; reciprocating pumps for liquids and gases WILLIAM R SELWOOD Ltd 22 Oct 1971 [29 Aug 1970] 41674/70 Headings F1A F1C and F1N [Also in Division F2] A rotodynamic pump 10, Fig. 1, is primed by a pump 11 comprising two pumping chambers 24 within each of which a relatively rigid central portion 26 is reciprocated by means of an eccentric 6 or a crank or cam, the central portion being connected to the wall of the chamber 24 by a thick sealing ring 29 of rubber or the like which is received in grooves or recesses at its inner and outer peripheries and is in a state of radial compression. The central portion 26 has a annular flap valve 28 of rubber or the like cooperating with a ring of ports 27. Annular flap valves are also used at the inlet and outlet of the pump 11, the inlet valve 30 co-operating with an annular inlet port 32 while the outlet valve 31 cooperates with a ring of ports 33. The pump 11 withdraws air from the main pump 10 via a valve controlled by a float 39, Fig. 3, within a float chamber 36. The valve comprises a spigot 37 engaged by a valve disc 38 of rubber or the like, the disc 38 and the flexible hinge 39a supporting the float 39 preferably being integral parts of a moulding. A non-return valve at the discharge side of the main pump 10 comprises an annular element 50, of rubber or the like, of truncated conical, flared or like shape engaging the end face of the discharge pipe 16 with a wiping action. The element 50 is anchored in a groove 51 in a rigid plate 45 which is carried, preferably through a loose connection providing lost or universal motion, by an arm 49 pivoted at 47. To facilitate the handling of liquid containing solids in suspension, the impeller 17 of the main pump 10 may have large radial and axial clearances relative to the impeller chamber. For this purpose, the internal diameter of the impeller chamber may be 1À40 to 2À00 times the impeller diameter, while the axial distance between the impeller blades and the front wall of the impeller chamber may be 55% to 70% of the axial depth of the impeller chamber and 0À20 to 0À40 times the impeller diameter. The main pump may be of vortex or water-ring type.