Siemens SITRANS F M MAG 5000 Instructions Manual

SIEMENS
SITRANS F M MAG 5000/6000, Accessory: Cleaning Unit
EN
Contents
1 electrochemical cleaning unit
1 connection board.
Introduction The Siemens Flow Instruments cleaning unit is used with MAG 5000 or MAG 6000 19" version on sensors
MAG 1100, MAG 1100 F, MAG 3100. The cleaning unit can be used for applications where deposits accu-
mulate on the liner material and electrodes. Non-conductive deposits will reduce the electrode signal,
while conductive deposits will partially shortcircuit the electrode signal, in both cases deteriorating the
accuracy of the meter (depending on the character and thickness of the deposits).
Warning
During cleaning there are high voltages on the electrode cables.
1. Do not touch electrodes and stripped electrode cables.
2. Not to be used in explosion hazardous areas.
3. Not to be used on flammable or explosive media.
4. Do not connect the cleaning unit to a flow simulator, etc.
5. Not to be used with sensors with Hastelloy or Tantalum electrodes.
Mode of operation The cleaning unit is used for electrochemical cleaning of the sensor (electrodes) by applying voltage for
approx. 60 seconds. Metering is resumed after another 60 seconds when cleaning is complete. During
cleaning (120 seconds) MAG 5000/6000 retains the last flow reading in the display and in the signal out-
puts until metering is resumed.
The relay output of the signal converter determines when to clean. In the signal converter the cycle time
can be set at 1 to 240 hours. If the cleaning cycle is set at e.g. 3 hours, the signal converter will clean the
electrodes every three hours.
Always make sure there is liquid in the pipe when cleaning. Use the "empty pipe detection" function (ON)
in the signal converter to detect when the cleaning unit can be used.
The cleaning sequence can also be controlled manually through the electrical input of the transmitter.
Before this is done, ensure that the measuring pipe is full.
AC cleaning
AC cleaning is used to remove fatty deposits from the electrodes.
These fatty deposits are seen in waste water applications, in abattoirs and water applications with oil residuals.
During the cleaning process, the surface of the electrodes get warmer, which tends to soften grease particles
and the gas bubbles generated mechanically lift deposits away from the surface of the electrodes.
Note: Do not use AC cleaning on sensors with Tantalum or Hastelloy electrodes.
DC cleaning
DC cleaning is used to eliminate electrically conductive deposits in the measuring pipe influencing the
measuring accuracy.
Particularly in district heating applications an electrically conductive deposit (magnetite) may occur and
short-circuit the electrode signal. In this case the accuracy of the meter decreases and the signal/noise
conditions of the meter become inferior.
The problem only arises if the conductivity of the water is less than approx. 250 µS/cm.
During DC cleaning electrolysis takes place where the flow of electrons removes the particle deposits
from the electrode area.
Note: Do not use DC cleaning on sensors with Tantalum or Hastelloy electrodes.
SFIDK.PI.026.J3.02 083R9148
Copyright © Siemens AG 03.2009. All rights reserved
INSTRUCTIONS
SITRANS F M