16
OIO 15en Edition 2020-05
Operating Instructions
Description
Function description
Function description
Description
KRAL flowmeters belong as screw meters to the group of rotating displacement meters. In a screw
meter a special form allows an almost tight engagement of two intermeshing screws
3, 6
to be achieved.
Together with the measuring housing
5
that encompasses the measuring unit, closed volumes are
achieved by this means. The fluid current makes the measuring unit rotate. The displacement effect
results from the continuous filling, axial displacement and discharge of the volumes described above.
The free cross-section of the measuring unit is constant throughout its length so that the flow rate can be
calculated simply from the product of the free cross-section, rotation speed and pitch of the screws. The
measured liquid flows around and lubricates all the rotating parts. The liquid is supplied and discharges
axially and almost without deflection. Thanks to the displacement principle described here, the
flowmeter does not require inlet and smoothing sections in its supply and discharge. The flowmeter can
be operated in any installation position and flow direction. The preferred direction of flow is indicated on
the rating plate by means of a bright arrow. Depending on the customer requirements, the flowmeters
can be equipped with correspondingly adapted end connections for connection to various flanges.
Rolling bearing
The measuring unit is maintained without contact and with a low degree of friction in the housing of the
KRAL flowmeter by means of a precision rolling bearing. Single-row deep-groove ball bearings are used
for Series OME KRAL flowmeters.
Fig. 1
Flowmeter design, OME Series, Version BEG 56
Fig. 2
Flowmeter design, OME Series, Version BEG 47C
1
Connection
2
Pick up hole
3
Measuring screw small
4
Ball bearing
5
Measuring housing
6
Measuring screw large
4
1
2
2
1
5
3
4
6
4
1
2
2
1
5
3
4
6
