Installation
VA 520 Bi directional English V1.21
Page 9 of 45
6
Installation Description
6.1
Pipe/tube requirements
•
Correctly sized gaskets
•
Correct aligned flanges and gaskets
•
Diameter mismatch at the pipe junctions should be avoided but must be less than 1mm.
For
further information see ISO 14511
•
Ensure clean pipes after installation
6.2
Inlet / outlet runs
The principle of thermal Mass flow measurement is very sensitive against disturbances. Therefore, it is
necessary to ensure the recommended inlet and outlet runs.
Table of additionally required inlet sections
Flow obstruction
in front of
the
measuring section
Minimum length inlet
section (L1)
Minimum length
outlet section (L2)
Slight curve
(bend < 90°)
12 x D
5 x D
Reduction
(pipe narrows towards the meas. section)
15 x D
5 x D
Expansion
(pipe expands towards the meas. section)
15 x D
5 x D
90° bend
or T-piece
15 x D
5 x D
2 bends á 90°
on one level
20 x D
5 x D
2 bends á 90°
3-dimensional change of direction
35 x D
5 x D
Shut-off valve
45 x D
5 x D
15 x D
5 x D
15 x D
5 x D
15 x D
15 x D
5 x D
20 x D
5 x D
35 x D
5 x D
5 x D
45 x D
The respective minimum values required are indicated here. If it is not possible to observe the
stipulated equalising sections, considerable deviations in the measuring results must be expected.
Attention:
The dimensions of the VA 520 consumption counter measuring sections do not fullfill the required
minimum lengths of the input and outlet runs.
Please ensure recommended in - and outlet distances, dimensions for measuring sections see page
12 and 13.
