6
SERVICE
14
H250 M10
www.krohne.com
06/2012 - 4001058901- MA H250/M10-Ex-II2G-AD R02 en
Service
6.1 Maintenance
Maintenance work of a safety-relevant nature within the meaning of explosion protection may
only be carried out by the manufacturer, his authorised representative or under the supervision
of authorised inspectors.
To maintain proper condition, regular inspections are required for systems in hazardous areas.
The following checks are recommended:
•
Checking the housing, the cable entries and the feed lines for corrosion and/or damage.
•
Checking the measuring unit and the piping connections for leakage.
•
Checking the measuring unit and the indicator for dust deposits.
•
Including the flowmeter in the regular pressure test of the process line.
6.2 Dismantling
General notes
If it is absolutely necessary to open the flameproof enclosure of the electronics compartment in
the presence of a potentially explosive atmosphere, the device must be de-energised. For
temperature classes T6 and T5, be absolutely sure to wait until the time shown on the converter
nameplate has elapsed before opening the flameproof enclosure (8 minutes). The waiting period
is not necessary for any of the other temperature classes.
Before connecting or disconnecting the electrical connection cables of the device, make sure
that all cables leading to the converter are isolated from the ground of the hazardous area. This
also applies to protective earth (PE) or functional earth (FE) and equipotential bonding
conductors (PA).
After opening the converter, grease the converter's flashback resistant cover threads including
the cover seals if necessary. Use the multi-purpose grease NONTRIBOS
®
, type Li EP2.
Replacing the signal converter / display
The device should be de-energised before opening the flameproof enclosure.
The display can be exchanged once the flameproof enclosure of the electronics compartment
has been opened. When exchanging a complete display, refer to the section "Connecting power
and I/O functions". In both cases, the measuring tube of the variable area flowmeter can remain
in the pipeline, even when the product is flowing.
CAUTION!
Avoid electrostatic charges when cleaning the surfaces (e.g. sight window).
CAUTION!
Only displays that are identical in construction and complete signal converter housings may be
swapped. Individual device inserts may not be exchanged! When exchanging signal converters,
compare the type plates. Only signal converters that are identical in construction may be
exchanged
AD_H250_M10_II2G_R02_en_058901_PRT.book Page 14 Tuesday, June 26, 2012 7:20 AM