4 Description
Operating manual mzr-7240
10
Technical data subject to change without prior notice!
Last update: March 2019
Example
: The pump mzr-7240 feeds with its displacement volume of 48 µl with
3000 RPM and a volumetric efficiency of 100 % referring to the above-
mentioned formula the flow rate of 144 ml/min. The following table shows the
volumetric displacement in dependence to the number of revolutions (
η
Vol
=
100 %).
Speed
[rpm]
Q
[ml/min]
Q
[ml/h]
500
24
1440
1000
48
2880
2000
96
5760
3000
144
8640
4000
192
11520
5000
240
14400
6000
288
17280
table 2
Theoretical flow rate of the micro annular gear pump
The pressure, which the pump has to generate, is given by the construction of
the fluidic system and the results of the hydrostatic pressure and the hydraulic
resistants (given by tubes, contractions etc.).
The viscosity of the pumping medium has an important influence on the
volumetric efficiency. The volumetric efficiency increases with higher viscosity
according to the smaller disengagement through the gaps of the pump.
Cavitation is an effect, which can result in a specific ceiling speed. The reason
for this is the static pressure reaching the steam pressure of the liquid in the
inlet port of the pump. In this state an increase of speed does not result in an
increased flow rate. The formation of gas prevents a sufficient feeding of the
pump. With increasing viscosity of the liquid (e.g.> 10.000 mPas), the ceiling
speed is lower.
The specific feature of the
mzr
-pumps is their highly precise design, as well as
the guarantee of high accumulator pressure and high accuracy in flow rate and
dosage. Therefore, space width and transverse space width of the rotors as well
as the interspace to the adjacent case parts are in the range of just a few
micrometers. This precision is at the same time the criterion to achieve a
volumetric efficiency in the range of approx. 100 %.
4.2
Construction
The micro annular gear pump is composed of the pump head, the coupling
unit, the drive and the angle support (see figure 5).
