GB804289A - Improvements in pumps for raising liquids - Google Patents

Abstract

804,289. Screw pumps; stuffing-box substitutes. PLASTIC CONSTRUCTIONS, Ltd. Feb. 14, 1957 [Feb. 15, 1956], No. 4675/56. Classes 110 (1) and 122 (5). In a pump comprising a number of screwtype impellers carried by a shaft within a casing to raise liquid in the casing up to an outlet, the impellers being spaced apart along the shaft to provide unrestricted spaces between adjacent impellers, the impellers and the casing are of acid-resistant material, and the shaft is of metal and is surrounded by, and fixed to, a tube or covering of acid-resistant material, the tube or covering carrying one or more of the impellers. A pump intended for insertion into a carboy for pumping acid from the carboy comprises three impellers 2, 3, 4, Fig. 3, each comprising a two-start screw thread. Unrestricted annular spaces 31, 32 extend between the impellers. The acid enters the pump casing 1 through holes 8 and is delivered through a pipe 9, Fig. 2, near the top of the casing 1. A tube 11, which may be shrunk on the driving shaft 5 and secured to it by pins 12, carries the two upper impellers 2, 3 and is secured as by welding to all three impellers 2, 3, 4. Impeller 4 has an extension 13 which forms a footstep bearing with a closure plug 7. A stationary carbon ring 22 is pressed by a spring 30 into sealing engagement with a carbon ring 23 rotating with the shaft 5. The rings 22, 23 are carried by resilient sleeves 25, 24 respectively. Sleeve 24 is clamped between a nut 27 and a flange formed on a bush 26 secured to the shaft 5. Sleeve 25 is clamped into a recess in a closure plug 6 by means of a ring 29. Further sealing is provided by a gland 34 and packing 33. A ring carried by side members 20 supports the driving motor 17, Fig. 1 (not shown). A handle (not shown) for supporting the pump may be carried by the motor. With the exception of the rod 5, which may be of stainless steel, the carbon rings 22, 23, the pins 12 and the spring 30, all parts of the pump and the sealing means are of an acid-resistant plastics, such as polyvinyl chloride. Other materials may be used, however, if the liquid handled is not an acid. The impellers may have single-start threads. Two or more than three impellers may be provided.