Positive displacement pumps are divided into two categories reciprocating pumps and rotary pumps. Positive displacement pumps are characterized by an almost constant flow with fluctuating back pressure.
A back-flow of the medium during standstill of the pump is prevented by the rotary valves or piston itself. Positive displacement pumps are usually self-priming.
Electric diaphragm pumps are pumps that operate according to the displacement. The axial deformation of the diaphragm, the medium of the pumping chamber is moved into the discharge line. By resetting the diaphragm to its initial state, the medium is sucked into the pumping chamber. Valves prevent the return flow of the liquid. The diaphragm is the sealing element to the atmosphere. Diaphragm pumps are self-priming and suitable for dry running. Since the service life of the membranes may be limited depending on use, this may need to be replaced.
Air operated diaphragm pumps
Air-operated diaphragm pumps are pumps that operate according to the displacement. The compressed air flows alternately in the two membranes. The axial deformation of the diaphragm, the medium of the pumping chamber is moved into the discharge line.
After the escape of compressed air behind the diaphragm, the diaphragm is returned to its original state and the medium is sucked into the pumping chamber. Valves prevent the return flow of the liquid. The diaphragm is the sealing element to the atmosphere. Diaphragm pumps are self-priming and suitable for dry running.
Impeller Pumps are rotary positive displacement pumps with pulsation-free and continuous flow. The flexible impeller rotates eccentrically arranged feed chamber. The vanes of the impeller to turn at the costs associated with the eccentric arrangement bottleneck and the pumped liquid is pressed out. If the blades open again in the further course, a new medium is drawn … The direction is reversible.
The pump also media containing particles such. Ex. Beer remains, seeds or stems. The pumps are self-priming and geeigne for short-term dry running
Micro annular gear pumps
Micro annular gear pumps are positive displacement rotary miniaturized. They are based on the so-called micro annular gear principle with an externally toothed internal rotor and an internally toothed outer rotor. The inner rotor has one less tooth than the outer rotor. To use the gear ratios get 6/7 and 10/11. The manufacturing tolerances of the rotors are a few microns in the area.
The product range includes five series of micro annular gear pumps for metering and promoting low volume liquid low to high viscosity media. With different equipment dosing volumes are from 0.25 .mu.l, flow rates of 1 ul / h to 1.1 l / min and pressures from 0 to max. 150 bar feasible. The range of media viscosity ranging from 0.3 to 1,000,000 mPas.
They are suitable for lubricating and non lubricating liquids. Operation in explosion-proof area is also possible. The pumps are characterized by low pulsation, low-shear promotion, low void volume, long service life, low weight and a compact design, self-priming behavior and wear and corrosion resistant materials.
Eccentric pumps are rotary positive displacement pumps. In fixed elastic stator, the thread-like shaped rotor rotates. The emerging between stator and rotor feed chambers move continuously from the suction side to the pressure side.
Progressive cavity pumps are self-priming and suitable for abrasive and highly viscous media.