Sensor
Offset
Customer
Selected
Full scale
Headrise
Vcal
Sensor
Mounting
Dimension
Level of fluid at no flow
6° Beam Angle
NOTE:
If sensor is exposed to sunlight, a sun shield should be used. Refer to System Diagram, Page 1-3.
The
sensor
offset
is the distance from the maximum level
of the fluid to the face of the sensor. The minimum offset is
12 inches.
The
full scale headrise
is the level of the fluid at the
customer’s selected full scale flow
for the flume or weir.
The minimum full scale headrise is 4 inches and the
maximum is 132 inches.
Therefore,
Sensor vertical mounting distance (Vcal) =
Customer full scale he Sensor offset
When the Model 2100 is programmed at the factory, the
Vcal is determined by taking the full scale head rise of the
maximum capacity of the flume or weir plus 12 inches for
the offset. This is done so that the flowmeter can be rescaled
to a higher full scale flow in the future without having to
move the sensor. This is reflected on the Mounting and
Calibration Data Sheet in the front of the manual by the
Max. Capacity (Element) and Customer Maximum
Headrise. When the Customer Max. Flow is less that the
Max. Flow (Element) then the sensor offset will be 12
inches plus the difference between Max. Flow (Element)
and the Customer Max Headrise.
The other mounting dimension that is important is the
Horizontal (H) dimension. This is the horizontal distance
from a reference point on the flume or weir to the sensor.
Pages 2-6 through 2-9 show this dimension for the
commonly used flumes and weirs.
Another aspect that must be considered when mounting
the sensor is the distance of the sensor from the walls of the
structure in which the fluid is flowing. If the sensor is too
close to the wall, reflections may occur which could cause
inaccuracies in the level measurement. The beam angle of
the transmitted signal from the sensor face is a maximum of
6 degrees. To determine the distance the sensor must be
mounted from the wall, multiply the Vcal distance times
0.0524. This will give the distance required from the wall to
the sensor housing.
The exit hole for the sensor cable on the top of the
housing is a 3/4" NPT nipple which is used to mount the
sensor to the mounting bracket and connecting the conduit
for the cable.
The cable must be run in metallic conduit to
prevent any stray noise interference from affecting the
meter’s operation.
The mounting bracket provided with the sensor can be
mounted directly to the wall for Vcal distances of 60 inches
or less. An extension, or mounting brace, to the mounting
bracket will be required for Vcal distances greater than 60
inches.
When installing the sensor, it is imperative that it be level.
A level should be placed on top of the sensor and
adjustments made to the mounting bracket to ensure the
sensor face is level to the fluid.
This completes the FB-1 sensor installation procedure.
Refer to the electronic wiring section for connecting the
sensor cable to the electronics.
2-5