Vaisala DMT346 - Manual (Page 35)

Chapter 3 ________________________________________________________________ Installation
VAISALA ________________________________________________________________________ 35
Description of the Cooling Set
Figure 18 Cooling Set Dimensions (in mm)
The cooling set consists of a cooling element and removable cooling fins.
The cooling fins are meant to be installed in applications where the
process temperature and dewpoint are continuously in the range indicated
in Figure 19 on page 36 (Measurement Ranges with and without the
Cooling Fins). However, if there is a possibility that the dewpoint is
above this range, the measurements have to be taken without the cooling
fins in order to avoid condensation.
The flow rate and ambient temperature have an effect on the cooling rate.
In Figure 19 on page 36, it is assumed that ambient temperature is
+25 °C. When ambient temperature is raised by +10 °C, the measurement
ranges with and without cooling fins rise approximately +6 °C.
Correspondingly, every -10 °C change in ambient temperature changes
the ranges by approximately -6 °C. It is recommended that after installing
the transmitter without the cooling fins, the transmitter is allowed to
stabilize and then the SSR reading is checked either from the local
display or with a terminal connected to an RS line. If the SSR reading is
below 20 %, it is recommended that the cooling fins are installed.
NOTE Make sure that the upper limit of the dewpoint measurement range is not
exceeded in low temperatures as this would lead to condensation.
304
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40.6
mounting
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sintered
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9
(fixed on top of
the cooling set)
cooling element cooling fins