s
ome fundamentals of centrifugal pump design for the chemical process industries
The primary pump problems in the chemical industry involve materials of construction, gland and seal leakage, and bearing failure. Unless pumps are specifically designed for chemical serv ice, unless materials of construction are selected to handle specific corrosive conditions, unless maintenance is sim ple and parts standardization is high your pumps may be the biggest head ache in your entire operation. Materials of construction DURCO has spent 50 years developing alloys and materials for practically any corrosive service. Pumps and pump parts are available in fourteen standard and many special corrosion resistant alloys. All of these are cast in the Durco foundry to retain complete responsibility for the excel lence of your equipment. Chlorimet 2 Chlorimet 3 Durco D-10 Durichlor Duriron Durimet 20 Durcon (modified epoxy resin)
Ductile iron 18-8-S (304 s.s.) 18-8-S-Mo (316 s.s.) Monel Nickel Ni-Resist #2 Inconel
Specific design for Chemical Service Shaft run-out and deflection have been the major causes of seal deterioration,
gland leakage and bearing failure in pump operation. DURCOPUMPS have shafts with diameters substantially larger than those traditionally used in centrifugal pumps. Shafts have a max imum run-out of .0015" with centerline deflection of no more than .005" at the impeller under maximum hydraulic load. Bearing housings are a thru-bore design, assuring perfect alignment. With this minimum deflection, packing and mechanical seals last far longer under operating conditions. Long bearing life Reduced shaft deflection has made it possible to build Series H pumps for 3500 rpm operation. Heavy duty bear ings are selected for a minimum life of two years at this speed under maximum operating stress. The normal life is many times greater than this. Bearings are sealed against oil leakage and ex ternal contamination by Durco de signed Teflon* lip seals. Many additional features designed into the Series H Durcopump give max imum flexibility in service. The casing is end suction, top center discharge and self venting with integral feet. Since it uses a rear cover closure, the pumping unit can be removed without disturbing the casing or disconnecting the process piping. No drilled holes enter the cas ing at any point. Impellers are threaded into the pump shaft, eliminating the impeller nut, and thereby greatly reducing the required NPSH. Head and/or capacity for any pump may be changed merely by changing the impeller diameter. A hori zontal seal ring permits adjustment of the impeller without increasing stuffing box pressures. By the use of an adapter between
the casing and bearing housing, eight pump sizes can be mounted on one bearing housing, utilizing one shaft. As a result, just four bearing housings will handle the complete range of Durcopumps. Since each is engineered for the maximum pump size in its range, most Durcopumps will have a built-in safety margin far beyond normal service re quirements. Simplified Maintenance Simplified, low-cost maintenance re sults from maximum parts interchangeability and minimum down-time. Bearing housings, shafts, and frame adapters on all Durcopumps are in terchangeable over a wide range of pump sizes. A complete range of pumps can be maintained in your plant with a surprisingly small spare parts inven tory. The foot mounted reverse casing de sign was first applied to chemical pumps by Durco. This design holds process down-time and maintenance costs to a minimum. Pumps are de signed for single trade maintenance. A millwright or mechanic can remove all rotating parts of a Durcopump from the casing in a matter of minutes. Neither the piping nor the motor need be disturbed. This means that rebuilt or new assemblies can be installed with little or no realignment. Durcopumps are available in sizes from Γ χ 1" to 10" χ 8" with capacities from Vi GPM to 4250 GPM, and heads to 345 feet. Durco also manu factures self-priming and submerged pumps for most corrosive services. You will find that your local Durco Engineer is a reliable source of infor mation on pumping problems and equipment. *DuPont registered trademark
THE DURIRON COMPANY INC., Dayton. Ohio/ Serves the process industries
|DURCO
