APG DCR-1004 user manual - Manual (Page 32)

DCR-1003 and DCR-1004 Rev. A3, 10/08
32
Automation Products Group, Inc.
APG...Providing tailored solutions for measurement applications
Tel: 1/888/525-7300 • Fax: 1/435/753-7490 • www.apgsensors.com • [email protected]
OPEN CHANNEL FLOW
The DCR-1003, 1004 and DST ultrasonic system can be used to compute the
flow of a liquid in an open channel such as rivers, canals, and partially filled
conduits. The flow is determined by using the DCR/DST system to measure the
liquid level upstream from a weir or flume. Weirs and flumes are simply special
shaped dams or restrictors built in a channel. Each type of weir or flume has an
associated equation for calculating flow. By programming the specified
constants into the DCR Controller and installing the DST sensor to monitor the
upstream depth of the weir or flume, an exact flow measurement can be
continually obtained. All relay and analog outputs must be programmed in the
units of flow.
The standard flow equation for a weir or flume is:
Q = KH^X
where
Q = flow
K = constant
H = head, or water depth to zero point
X = exponent
The equation for the weir or flume being used can be obtained from the
respective manufacturer. Two examples will show how the DCR/DST system can
monitor flow.
used to convert distance to flow.
3-4H MINIMUM
SENSOR
LOCATION
CREST
MIN. CREST 2-3H
MIN. BLANKING DIST.
RECTANGULAR WEIR
MAX HEAD, H