VARISCO SaxMag V Series, Operating Manual

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OPERATING MANUAL - SAXMAG V
Page 14
4
Description of the product and accessories
4.1 General description
4.1.1 General description of the pump
V-Series internal gear pumps are volumetric rotary displacement pumps with internal gears designed to
deliver fluids of any viscosity. The flow of the fluid to be delivered is produced by two gears: The directly
driven rotor designed as a gear and the pinion which, also designed as a gear, engages the rotor in an
off-centre configuration.
Rotor and pinion are isolated from one another by a stationary steady (crescent-shaped partition). For
the pumped fluid to be drawn in (inlet), the teeth of the rotor and the pinion in engagement will come out
of mesh, whereas the teeth moving into mesh will result in discharge of the fluid (outlet).
The pump shaft is supported in the bearing housing in a plain bearing; similarly, the pin of the pinion
(single-ended shaft) is also supported in a plain bearing. The plain bearings are lubricated by the
pumped fluid. The pumps are self-priming. Optionally, the pumps are equipped with a safety relief valve
(a pressure relief valve designed as a bypass). When the valve operates, as a rule fluid will flow from the
discharge side to the suction side of the pump, which - in an extreme case - can entail recirculation
(internal circulation) with overheating.
It is the key property of pumps with magnetic couplings (V SAXMAG Series) that they are driven through
a magnetic coupling. The external magnet core is connected to the motor shaft; it serves to transmit
the torque to the internal magnet core that is mounted to the pump shaft. The magnetic field generated
by the motor-driven magnet hub with the externally placed set of (permanent) magnets causes the
internal magnet core and, thus, the rotor to rotate.
Arranged between the two magnet cores is a containment shell which hermetically seals the pumped
fluid from the atmosphere without any shaft seal fitted. Suitably designed coolant and lubricant grooves
are provided to continuously dissipate heat to which the magnetic coupling is exposed because of eddy
current losses. The coolant flow is returned to the pump's suction side through the gap between the
containment shell and the internal rotor, via the internal rotor's rear side and a centre port in the pump
shaft.
Pumps with a drive-end magnetic coupling and a pressure relief valve at the opposite end do not have
any dynamic shaft seals fitted. These pumps are hermetically sealed.
The drive shaft which mounts the magnet hub at its drive end is supported in the bearing flange in two
ball bearings with a shaft seal made of Perbunan fitted to cover the bearings towards the outside.
Where it is desirable to monitor the temperature on the magnetic coupling the pumps can be equipped
with a PT 100 temperature sensor that is inserted into the flange of the containment shell from above.
Moreover, provision for PT 100 temperature monitoring is made directly on the pump casing.
The maximum operating pressure for all pump types is in the range from 8 to 16 bar, depending on
pump type, design and operating conditions.
The ambient temperature range T
A
is: - 40°C… to T
A
+ 60°C.
The maximum allowable operating temperature range (at the same time the pumped-fluid temperature
range) is: - 40°C to + 220°C.