KROHNE CORIMASS G-MFM 4085 EN - Manual (Page 15)

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Also available are special jacketed meters as shown in figure 19. These are also Ex approved.
Remote jacketed meter must be fitted with an insulation adaptor shown in fig. 13.
Figure 19
In all cases, the installation factor should be monitored and maintained within normal levels.
1.3.4 Heating Up From Cold
The proceeding insulation and heating instructions also apply in this case, together with the
following notes:
The low thermal coupling between the Titanium tube and the flanges means that maintaining a
G+ Meter at a desired temperature is straight forward as already described, however, heating
from cold an uninsulated meter can be a lengthy process, particularly if the customer’s product
could be damaged by high rates of heat input at the flanges. The areas at each end of the
meter can be heated from 20°C to 60°C in about 2 hours, but the centre of the meter can take 5
hours to reach this temperature particularly if the product has solidified. It is possible to speed
this up if the meter is mounted vertically and a reduction of about an hour is possible, if the case
is insulated. If the case is also heated, heating times are further cut.
The above comments assume that there is no flow through the meter. If there is flow through
the meter then the desired temperature can be reached within a few minutes.
Another important fact to note, is that it is rarely necessary to fully melt all the product which has
solidified in the meter, as it has been demonstrated that any ‘plug’ of product can be pushed
through the meter by pumping pressures of less than 1 bar. Any ‘plug’ would be rapidly melted
in the joining pipework. This fact is an important benefit of the single straight tube design and is
not true of bent tube meters, or meters with flow dividers and multiple tubes.
Temperature Note
Most work in this subject has considered product temperature up to 80°C, if higher
temperatures are required by the customer the proceeding guidelines still apply, but heat up
from cold times will be extended.
The G+ Meters have maximum operating temperatures, as follows:
Zirconium Tubes 100°C
Titanium Tubes 130°C
Titanium Tubes (to special order) 150°C