Patent GB-490490-A (GB)
Title: Improvements in or relating to liquid dispensing apparatus
IPC: B67D7/76
Filed: 1936-11-14
Abstract: 490,490. Priming centrifugal pumps. WAYNE CO. Nov. 14, 1936, No. 33055/37. Convention date, June 15, 1936. Divided out of 490,515. [Class 110 (i)] A centrifugal pump for dispensing liquids in bulk is primed by an ejector continuously connecting the inlet and outlet of the pump, the flow through the jet being towards the inlet and continuous. The discharge conduit of the pump has a valve which is normally closed but is opened by the pressure caused by the substantial elimination of air or vapour from the suction side of the pump. The outlet of the ejector connects to an air separator and the conduit between the separator and the pump inlet is controlled by a valve operated by a float in the separator. The dispensing apparatus shown in Fig. 1 comprises a centrifugal impeller 24 with suction and discharge chambers 28, 30, the latter leading through differential valve 32, pipe 34, meter 36, sight gauge 42, and line 44 to nozzle 46. The priming device comprises pipes 52, 66 leading from the impeller 24 and chamber 30 to the ejector 64 which communicates with the air separator 76 having a float 80 operating a valve 88 in the conduit 92 connected to chamber 28. Valve 32 is connected to the suction side of the pump by pipe 106. The ejector draws air from the eye of the impeller through extension 56 and also from chamber 28 through aperture 54 in pipe 52. The pumping and ejector unit of Fig. 7 comprises a motor 178 with shaft 176 coupled to the shaft 166 of an horizontal impeller 158. The suction chamber 148 has a baffle 152 to maintain the liquid height in the impeller chamber 160 and communicates with the eddy chamber 154 leading to the impeller. To prevent the impeller from becoming air bound and to prevent upward surges of liquid, its upper rim is housed within a perforated collar 165 secured to the eddy chamber 154. Chamber 160 leads to the differential valve 208 and discharge chamber 204 and also to the jet 182 and jet tube 186 mounted in the jet chamber 184 which is in communication with valve 208. Jet tube 186 leads to float chamber 190 with valve 194 connecting to eddy chamber 154. The differential valve may have a piston influenced by the partial vacuum in the jet chamber. The pumping and ejector unit of Figs. 9, 12 comprises a drive-shaft 440 coupled to a vertical impeller 468. The chambers provided are suction 462, eddy 492, impeller 464, jet 504, float 460, vent 532, pilot piston 552, equalizing 576, and discharge 584. The jet 542 communicates with chamber 464 and the jet tube 544 with chamber 460. The pilot piston 554 is mounted on a valve stem 560 carrying the piston 566 and valve. 578. A pressure difference between chambers 504 and 552 on the one hand and chamber 462 due to the pumping of air-free liquid lifts valve 578 to permit outward flow of liquid through discharge 584. This flow also reduces the pressure in chamber 576 to hold the valve open. In a modification, the pilot piston governs ports leading to the equalizing chamber. Another unit with vertical impeller, Figs. 17, 18, comprises a motor 636 with shaft 638 coupled to an impeller 558 in chamber 656. The suction chamber 664 leads from eddy chamber 713 having a baffle 712 to maintain the liquid height. Float, vent, and ejector chambers 674, 676, and 716 are also provided. The jet 720 and jet tube 718 lead to a passage 726 having a curved wall 728 to give the liquid a swirling motion to release entrapped air. The differential valve 734 carries the piston 740 and receives the valve rod 756 attached to pilot piston 768. The space 784 behind the impeller 558 communicates with a chamber 788 which is vented at 792 either to the float 674 or suction 664 chambers. A modified form of differential valve which has a hollow stem carrying a piston and having apertures leading to an equalizing chamber is also described. The upper end of the stem may be closed by a valve on the pilot piston so as to byepass the discharge chamber to the jet. When the air is removed from the liquid, the pilot piston lifts, the pressure in the equalizing chamber drops and the differential valve opens the impeller chamber to the main discharge. Specifications 397,035 and 490,515 are referred to. The Specification as open to inspection under Sect. 91 is identical with Specification 490,515.