Mechanical installation
15
© 2016 Van Putten Instruments BV | MAN-VP-MPRO-UK | Revision:1602 | Date:20-10-2016
6.2
Piping table
Check the piping table below for your application. The table shows the amount of length upstream
or downstream depending on the installation. If applicable in front of the meter, use given upstream
length. If applicable in behind the meter, use given downstream length.
Gas flow in pipes follows
certain rules, which must be observed for optimal measurement results.
For some exceptions the
upstream length needs to be longer, or can be shorter.
If possible, you can always choose a longer upstream length, as these are minimum
values. The up- and downstream lengths are used industry wide as guidelines, but
will never be a guarantee for obtaining the “true value”.
Piping table
The following table provides a guideline for proper distances between upstream or downstream
objects and the VPFlowScope M. The upstream length is the length between the last non-straight
object and the VPFlowScope M. If the upstream length is straight, and the distortion is downstream
of the VPFlowScope M, you can use the column "downstream length" as a guideline. In very
complex situations, with multiple up- and downstream objects, you should consider another
location. This table is a practical guideline and is not exact science. Practical situations can have
multiple sources of distortion, therefore VPInstruments does not take any responsibility for the
correctness.
Picture
Description
Upstream
length
2
Downstream
length
2
Effect
Single elbow
30 * D
1
10 * D
1
Distorted flow profile
Complex feed-in
situation (header)
40 * D
1
10 * D
1
Flow profile will be
distorted
Double elbow, multiple
elbows following each
other
40 * D
1
10 * D
1
Distorted p
swirl
Diameter change from
small to large (gradual
or instant)
40 * D
1
5 *D
1
Jet shaped flow
