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40
MN310140 Rev A2
WebCal
®
Appendix
(continued)
Section Seven
VOLUMETRIC CONFIGURATION
The sensor may be configured in volumetric units
(Gallons or Liters) or Distance (Height of Liquid)
units (inches, cm, feet or meters). WebCal
®
will
default to Distance (Height of Liquid) with units of
Inches. To change units or change from Distance
to Volume, press the Volumetric Mode button as
located near the center of the window.
Distance (Height of Liquid):
When this is selected,
the sensor will always output a linear output
proportional to the height of liquid (regardless of the
tank shape). In the two drawings below, the Sensor
High is set to 64” and Fill-Height is set to 60”. If the
tank is empty, the sensor will output 4mA. If the level
is at 30”, then the sensor will output 12mA. Either
tank can be configured with a display from 0” to 60”
and the sensor will always output the height of liquid.
Volume:
When volume is selected, the 4-20 mA output from the sensor will be proportional to the volume of
the tank, not the height of the tank. This means that the current output will track the volume of the tank (in
gallons or liters). Depending on the shape of the tank, the values may be a linear or non-linear scale. In the
same examples below, the sensors are also configured with SH = 64” and FH = 60”. The current output in a
linear tank will act as expected with volume increase matching equal changes to level. However, the current
output in the Non-Linear tank will reflect the actual changes in volume. So even though the liquid height
changes incrementally the same amount, the volume change will adjust throughout the entire span of the tank.
The advantage of this is that sensor does all the math so you can read tank volume using a simple two-point
display/controller such as the DataLoop
™
LI25 series or DataView
™
LI55 series.
Linear Tank Example
Note:
In the above illustration, 10” of liquid will
always be equal to 100 gallons of liquid (1” = 10
gallons).
Non-Linear Tank Example
Note:
In the above illustration, 1” of liquid does not
equal 10 gallons. The 10” at the bottom represents a
rise of 62.8 gallons. As a change between 10” and
20” represents an increase of 109.6 gallons (i.e.
172.4 gallons – 62.8 gallons).
