can make the balancing filter 13 of level indicator FMN 113 ineffective after a long operation time:

• Clean the dust collectors regularly (if necessary replace them).

Sharp edged filling material

can cause abrasion of the diaphragm:

• Regularly check the diaphragms(if necessary replace them).

Exchanging diaphragms:

• Detach and remove the screws of the diaphragm guard ring 2(3).
• Exchange diaphragm 4(5).
  The plane surface on the diaphragm must be outside.
• Plug the screws into the holes of the new diaphragm and the guard ring and tighten adequately.
  The bolt circle on the flat diaphragm is deliberately a little larger than the guard ring. Thus the initial tension of the diaphragm isn't too high.
• Readjust the level indicator afterwards.