Emerson Rosemount 702 Reference Manual page 10

Rosemount 702
Figure 1-1. 702 Transmitter
Connection Head Temperature
Rise vs. Extension Length
1-4
Figure 1-1 provides an example of the relationship between transmitter
housing temperature rise and thermowell extension length.
60 (108)
50 (90)
40 (72)
55
30 (54)
20 (36)
10 (18)
0
Example
The transmitter specification limit is 85 °C. If the ambient temperature is 55 °C
and the max process temperature to be measured is 815 °C, the maximum
permissible connection head temperature rise is the transmitter specification
limit minus the ambient temperature (moves 85 to 55 °C), or 30 °C.
In this case, an extension of 5" meets this requirement, but 6" provides an
additional margin of thermowell protection, thereby reducing risk of ambient
thermal damage.
Temperature Limits
Operating Limit
With LCD Display –4 to 175 °F
–20 to 80 °C
Without LCD Display –40 to 185 °F
–40 to 85 °C
815 °C (1500 °F) Process Temperature
540 °C (1000 °F) Process Temperature
250 °C (482 °F) Process Temperature
3 4 5 6 7
4.2 Extension Length (in.)
Storage Limit
–40 to 185 °F
–40 to 85 °C
–40 to 185 °F
–40 to 85 °C
Reference Manual
00809-0100-4702, Rev AA
September 2007
8 9