KROHNE ALTOSONIC III EN - Manual (Page 33)

Installation and operating instructions
33 ALTOSONIC III
7. Service and
maintenance
7.1 Introduction Contact your nearest local KROHNE representative for ordering information of the UFC III…-EEx electronics units and/or
fuses.
The ALTOSONIC III ultrasonic flowmeters are maintenance free with regard to the flow metering properties. Within the
scope of the periodical inspections, which are required for electrical apparatus that is installed and used in a hazardous
classified location, it is recommended to check the flameproof converter housing on signs of corrosion and damages
7.2 Replacement of
electronics unit or
power fuse(s)
The following instructions must always be carefully followed, if the flow converter housing in which the UFC III…-EEx is
installed has to be opened respectively closed again!
Before opening:
• Make absolutely sure that there is no explosion hazard!
• Gas-free certificate!
• Make sure that all connecting cables are safely isolated from all external sources!
• Allow the prescribed waiting time to elapse before opening the housing: 20 minutes for temperature class T6 and 11
minutes for temperature class T5!
When the instructions above are strictly followed, the cover (including a glass window) of the electronics compartment may
be removed. First unscrew the recessed head screw of the interlocking device by a hollow-head screw wrench size 3, until
the cover can rotate freely. Unscrew the cover with the special plastic wrench (black) that is supplied with the apparatus.
After opening:
• The copper grounding strip at the back of the electronics unit must be securely screwed to the housing (back-end of
electronics compartment) by screw C (see figure below). The electronics unit is screwed into the electronics
compartment by two screws B. Before screws B and C can be accessed, the display unit must be removed via screws
A.
• Before the cover is screwed back into the housing, the screw-thread must be clean and well-greased with an acid and
resin-free grease, e.g. teflon grease.
• Screw the cover as tight as possible into the housing by hand, until it cannot be opened by hand anymore. Screw the
recessed head screw of the interlocking device tight.
Display unit Electronics unit after removal of display unit
A
C
A
B
B