4 Description of the pump
Operation manual mzr-2961, mzr-4661
12
Technical data subject to change without prior notice!
Last update: April 2018
efficiency is dependent on the media and the pressure against which it has to
be fed.
Example
: The pump mzr-4661 feeds with its displacement volume of 12 µl with
3000 RPM and a volumetric efficiency of 100 % referring to the above-
mentioned formula the flow rate of 36 ml/min. The following table shows the
volumetric displacement in dependence to the number of revolutions (
η
Vol
=
100 %).
mzr-2961
mzr-4661
Speed
[rpm]
Q
[ml/min]
Q
[ml/h]
Q
[ml/min]
Q
[ml/h]
500
1,5
90
6
360
1000
3
180
12
720
2000
6
360
24
1440
3000
9
540
36
2160
4000
12
720
72
2880
5000
15
900
60
3600
6000
18
1080
72
4320
table 4
Theoretical flow rate of the micro annular gear pumps
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 liquid 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 reduce the volumetric efficiency from in a
specific ceiling speed. With increasing viscosity (e.g.> 500 mPas), this ceiling
speed is lower. This is the result of the media specified underflow of the steam
pressure in the induction port of the pump, in which gases are building up in
the pump.
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 lie in the range of just a few
micrometers. This precession is at the same time the criteria to achieve a
volumetric efficiency in the range of approx. 100 %.
The micro annular gear pump head has an inscription on the front side (see
figure 8). The induction connection is marked with the letter »S«, the pressure
connection with the letter »D«. An arrow on the front side of the pump
indicates the inherent turning direction of the shaft.
