Features / Benefits

• capacities up to 100 m3/h
• pressures up to 120 bar
• high viscosities up to 100.000 cP (mPas)
• moderate to high abrasiveness
• mild corrosiveness
• up to 120 mm particle size
• up to 90% solids content

Where slurry consistency and particle size are beyond the handling capability of a crankshaft driven pump, consideration is given to hydraulically driven piston pumps. These are two cylinder, single-acting pumps with continuous water flush on the backside of the piston. These pumps are designed with a prerequisite low stroke rate, a low piston velocity and large flow areas, which also help to minimize wear. Cartridge mounted sensors are provided at either end of the hydraulic drive cylinders. Signals from opposed sensors/pistons enable a plc controlled stroke reversal and either piston to complete a full stroke. This method of leakage compensation enables the use of standard hydraulic piston seals, which afford a 5 to 100% capacity adjustment range. Larger size pumps use a linear transducer in lieu of sensors. lt reduces the length and weight of the piston and cylinder and enables a full stroke length independent of the stroke rate. The drive cylinder design, oil hydraulic flow sheet and plc programming aim to obtain a relatively smooth piston reversal and reduce hydraulically and mechanically induced loads. The larger size pumps accomplish piston pump stroke reversal by reversing the swash plate angle of the main oil pump(s) in lieu of manipulating a control valve. A detailed review of the slurry consistency, performance indicators and project requirements determines the choice for either of the two available piston pump models.

DHT – Piston pump with transfer tube
The model DHT’s pump water end comprises a hopper with transfer tube. This S-form pipe pivots on the discharge side whilst the inlet is intermediate between the opening of the paired cylinders. At the end of a suction stroke it covers the cylinder pening and isolates the filled cylinder from the suction hopper. During the subsequent discharge stroke, the piston forces the product through the tube into the discharge pipe. The tube inlet opening is fitted with a nozzle, which slides over a wear plate. Where the tailings are particularly abrasive, ceramics improve wear and galling resistance.

The size SR2 and SR3 hoppers are unique in that a hydraulic thrust load is generated, which pushes the tube against the wear plate. The tube nozzle is not required to move axially, but is flexibly mounted to compensate for uneven wear and misalignment. The swivel cylinders are positioned at a slight angle such that the nozzle to plate contact is maintained when the pump is idle. The tube turning lever is mounted on a tapered polygon, which provides a long term clearance-free and shock resistant fit.