RMG ERZ2000-NG, Operating Manual

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6 Flow meters
Manual ERZ 2000-NG · EN07 · 2019, May 13th
212
Profile and symmetry factory
With a fully developed flow, the middle paths (3 + 4) have the highest prevailing
speed, the two outside paths (1 + 2; 5 + 6) have about the same speed. The profile
factor (
PF
) is typically between 1.05 and 1.20; with values below 1.00 or above 1.50,
the flow conditions must be checked.
ܲܨ ൌ
ʹ ڄ ሺݒlj
ଷ
൅ ݒlj
ସ
ሻ
ሺݒlj
ଵ
൅ ݒlj
ଶ
ሻ ൅ ሺݒlj
ହ
൅ ݒlj
଺
ሻ
The symmetry factor (
SY
) is normally 0.90 – 1.10; with values below 0.75 or above
1.25, the measuring conditions must be checked.
ܻܵ ൌ
ሺݒlj
ଵ
൅ ݒlj
ଶ
ሻ
ሺݒlj
ହ
൅ ݒlj
଺
ሻ
Meter performance
This value (
MP
) indicates whether the speeds of all measuring paths could be deter-
mined and incorporated into the flow rate calculation. Calculation takes place for the
last 20 measurements (identical to the number for turbulence).
ܯܲ ൌ
σ σ
ͳ ሺר ݒ
௝ǡ௜
ൌ ݋݇ሻ ש Ͳ ሺר ݒ
௝ǡ௜
് ݋݇ሻ
଺
௜ୀଵ
ଵ଴଴
௝ୀଵ
͸ͲͲ
The value is a maximum of 100%; under normal conditions it is above 95%. Since 2
measuring paths can fail before a 6-path USM loses its calibrated accuracy, the value
may temporarily decrease to 66%; if the failure is due to a defective transducer, an
immediate repair of the affected transducer of the failed measuring path must be
sought.