Flow Application Example; Parshall Flume - Siemens SITRANS LUT400 Operating Instructions Manual

Commissioning
6.8 Application examples
The application is a vessel that takes an average 3 hours (180 minutes) to fill and 3 weeks to
empty.
Fill rate = (Low calibration point – High calibration point ) / fastest of fill or empty time
= (15.5 m – 1 m) / 180 min.
= 14.5 m /180 min. = 0.08 m/min.
6.8.2

Flow application example

6.8.2.1

Parshall Flume

In this example, a 12 inch (0.305 m) Parshall Flume has been installed in an open channel.
As per the supplier's data sheet, the device has been rated for a maximum flow of 1143
m per hour at a maximum head of 0.6 m.
3
The Parshall Flume is considered an exponential device, therefore the supplier's data sheet
includes a flow exponent value of 1.522.
The SITRANS LUT400, and the XRS-5 transducer have been installed 1.6 m above the
channel beside the TS-3 external temperature sensor.
During intermittent peak flow times, the head level can be expected to rise at a rate of
approximately 0.12 m/minute. The application also calls for a flow sampler to be activated
every 1000 m
the event of a loss of echo or cable fault.
①
Zero head
②
2/3 Converging dimension
③
Converging dimension
④
Transducer
80
, or 24 hours (whichever comes first), and for a fail-safe alarm to activate in
3
Operating Instructions, 07/2019, A5E33329501-AC
SITRANS LUT400