Components and mechanical specifications
The column pipe is of flanged carbon steel plate construction. The pipe columns are welded using automatic submerged arc welding processes. The plate thickness is 8mm for models 050 through 063, 10mm for models 071 through 125 and 12 mm for larger models. The pipe columns sections are machined between centers to ensure perfect alignment of the pump.
The impeller is of 316L or 304L stainless steel plate welded construction depending on application. Aerodynamic profile design using computerized fluid dynamics (CFD) and the surface finish provided by the laminated steel plate ensure higher efficiency than conventional casting methods.
The impellers are structurally designed using finite element methods (FEM) to withstand loads way above normal operation as well as the collision loads due to accidental entry of solid bodies. All impellers are dynamically balanced.
The Diffuser is of carbon steel or stainless steel plate construction. Diffuser guide vanes are stamped with diffusion angles that permit maximum conversion of kinetic energy into pressure energy. The cross sectional area is gradually enlarged to reduce losses due to flow separation. The diffuser is completely machined to ensure proper alignment with the column pipe and wear ring.
The wear ring is of 316L or 304L stainless steel plate construction depending on application. It is completely machined to allow a small clearance with the impeller and thus achieving high volumetric efficiency.
An electrical insulating system prevents galvanic corrosion between the stainless steel wear ring and the pump’s carbon steel components. Wear ring thickness is 8mm for models 050 through 071, 10 mm for models 080 through 125 and 12 mm for larger models to ensure long service life and structural stability.
For operation in less corrosive environments, the wear ring can also be of carbon steel construction.
Line Shaft Supports
Line shaft supports are of carbon steel construction and entirely machined to ensure perfect alignment of the shaft.
For easy of maintenance, the shaft is divided into three sections: head shaft, line shaft, and bowl shaft. In water lubricated pumps (open line shaft), the shaft is of turned, ground, and polished 316 or 304 stainless steel construction.
In oil lubricated pumps (enclosed line shaft), the shaft is of turned, ground and polished 1045 carbon steel construction. In all models, the head shaft is of 1045 carbon steel construction and the bowl shaft is of 316 or 304 stainless steel construction.
All fasteners are 316 or 304 stainless steel and are electrically insulated to avoid galvanic corrosion.
The Discharge Elbow is of carbon steel plate flanged construction and completely machined to ensure proper alignment. The plate thickness used in the discharge elbow construction is the same as that used in the column pipe.
The suction bell is of carbon steel or stainless steel plate construction. It is machined to ensure proper shaft alignment and designed for a gradual reduction in cross sectional area to avoid sharp directional changes in the flow pattern and thus minimizing losses due to flow separation at the pump entrance.
Head Shaft Coupling
DELTA’s water lubricated shaft pumps incorporate a unique head shaft coupling design. To avoid galvanic corrosion of the column, diffuser, and suction bell due to the presence of the stainless steel shaft and impeller, the upper shaft coupling is constructed with electrical insulation.
Standard finish for DELTA pumps consists of two coats of epoxy paint applied over a near white SSPC – SP10 grit blasted surface. The minimum coating thickness is 0.25 mm (10mils). The surface of the suction bell and diffuser are painted with two coats of abrasion resistant epoxy – ceramic paint.
For belt drive applications the pumps is supplied with a unique hollow shaft bearing system. Bearings are oversized to assure a minimum life of 30.000 hours of operation. An integral oil pump assures positive bearing lubrication. The hollow shaft design allows for easy vertical positioning of the impeller during pump start-up. A solid shaft bearing system can also supplied.