Reference Manual
00809-0100-4841, Rev. AA
May 2007
4-23
Rosemount 3490 Series
Profile Calculations for
Contents and Flow
Applications
The 3490 Series Control Unit can use level measurements to calculate the
content in linear or non-linear shaped closed-vessels. In addition, flow in
open-channels can be calculated and totalled. The 3490 Series Control Unit
has a library of pre-programmed profiles and supports a user-defined profile.
The data flow diagrams in “Transmitter inputs to the 3490“ on page 4-13 show
how the various parameters are used to calculate the final 3490’s PV.
NOTE:
You are strongly recommended to use the "Duty" Wizard for setting up
content and flow applications, as this will automatically calculate and populate
the relevant parameters. The Wizard will guide you through all the setting up
and populate parameters with values and settings.
Menu: SETUP / [CONTROL UNIT /] DUTY(Mode) / Duty Wizard
Linear Profile (Content from Level)
Parameter P113 must be set to "Scaled", which establishes that the
relationship between the liquid level and the content (PV value) derived from
that level is linear.
For the linear profile, e.g. vertical cylinder or rectangular vessel, parameter
P114 either defines the maximum content (if 4-20mA transmitter used) or area
of the vessel's cross-section (if HART transmitter used). The PV value (D800)
for the content is then calculated as the live level measurement multiplied by
the value in parameter P114.
Standard 4-20mA input (Figure 4-15 on page 4-15):
• P200 (units) must have changed from "%" to the required units of
measurement.
• P114 is used to define maximum contents of the linear profile vessel.
• The PV value (D800) is calculated using: D800 = P114 x (D802 / 100)
• Note that P115 and P116 are bypassed in this scenario.
HART digital input (Figure 4-17 on page 4-21):
• P200 (PV units) must be set to the required units of measurement.
• P114 is used to define the contents of the linear vessel per unit of level
measurement. If the input from the HART transmitter is in metres, the
value of P114 is the contents of the vessel per metre of height. If the input
from the HART transmitter is in feet, the value of P114 is the contents of
the vessel per foot of height.
• The PV value (D800) is calculated using: D800 = ( P114 x Level
measurement).
• Note that P115 and P116 are bypassed in this scenario.
Non-linear Profiles (Content from Level)
• Non-linear profiles for content:
• Horizontal cylinder with flat ends.
• Spherical vessel.
• Horizontal cylinder with domed ends.
• Special (plotted).
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