Endress+Hauser Proline Promag 55, Operating Manual

Page: 86 / 130

3 Transducer Block Device functions Proline Promag 55 FOUNDATION Fieldbus
86 Hauser
EPD - Empty Pipe
Detection AUTO - OOS This status can be monitored at all times with the Empty Pipe Detection
function. To do this, the empty pipe detection (EPD, empty pipe detection
by means of EPD electrode) can be activated in this function:
Options:
OFF
ON STANDARD
Factory setting:
OFF
!
Note!
• The option ON STANDARD is not available unless the sensor is
equipped with an EPD electrode (see "EPD - Electrode" parameter,
→
Page 87).
• The default setting for the EPD function when the device is delivered is
OFF. The function must be activated as required.
• The devices are already calibrated at the factory with water (approx.
500
µ
S/cm). If the conductivity of certain fluids deviates from this
reference, empty pipe/full pipe adjustment must be performed again on
site (see "EPD - Adjustment" parameter
→
Page 85).
• The adjustment coefficients must be valid before you can switch on the
EPD function (see "EPD - Adjustment"
→
Page 85).
• If there are problems with the adjustment, the following error messages
appear on the screen:
– EPD adjustment wrong - Err. No. 463:
The adjustment values for empty pipe and full pipe are identical. In
such instances, empty pipe adjustment/full pipe adjustment
must be
carried out again .
– EPD adjustment not possible - Err. No. 461:
Adjustment is not possible as the fluid conductivity values are
outside the permitted range.
Notes on empty pipe detection (EPD)
• Flow cannot be measured correctly unless the measuring tube is
completely full. This status can be monitored at all times with the EPD
function.
• An empty or partially filled pipe is a process error. A default factory
setting defines that a notice message is issued and that this process error
has no effect on the outputs.
• A plausibility check of the adjustment values will only be executed by
activating the empty pipe detection. If an empty or full pipe adjustment
is performed when empty pipe detection is active, the empty pipe
detection has to be deactivated and activated again after finishing the
adjustment in order to start the plausibility check.
Response to partially filled pipes
If the EPD function is switched on and is triggered by a partially empty or
completely empty pipe, this is indicated in the "Diag. - Act.Sys.Condition"
parameter (
→
Page 90) of the "Diagnosis" Transducer Block with the
error message "Empty Pipe detected - Err. No. 401".
This process error is relayed to downstream function blocks or higher-
order process control systems by means of the status "UNCERTAIN" of the
output value OUT (AI Block).
If the pipe is partially empty and the EPD is not switched on, the response
can vary in identically configured systems:
• Flow reading fluctuates
• Zero flow
• Excessively high flow values
"Flow" Transducer Block/base index 1400
Parameter
Write access with
operating mode
(MODE_BLK)
Description