Emerson Rosemount, Reference Manual

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4
Reference Manual
00809-0100-4021, Rev GC
Section 1: Introduction
April 2014
Introduction
Figure 1-1. 3144P Transmitter Housing Temperature Rise versus Extension Length for a
Test Installation
Example:
The maximum permissible housing temperature rise (T) can be calculated by subtracting the
maximum ambient temperature (A) from the transmitter’s ambient temperature specification
limit (S). For instance, if A = 40 °C.
T = S - A
T = 85 °C – 40 °C
T = 45 °C
For a process temperature of 540 °C (1004 °F), an extension length of 3.6 inches (91.4 mm)
yields a housing temperature rise (R) of 22 °C (72 °F), providing a safety margin of 23 °C (73 °F).
A 6.0 inch (152.4 mm) extension length [R = 10 °C (50 °F)] offers a higher safety margin [35 °C
(95 °F)] and reduces temperature-effect errors but would probably require extra transmitter
support. Gauge the requirements for individual applications along this scale. If a thermowell
with lagging is used, the extension length may be reduced by the length of the lagging.
1.2.4 Moist or corrosive environments
The 3144P temperature transmitter has a highly reliable dual compartment housing designed
to resist moisture and corrosion. The sealed electronics module is mounted in a compartment
that is isolated from the terminal side with conduit entries. O-ring seals protect the interior
when the covers are properly installed. In humid environments, however, it is possible for
moisture to accumulate in conduit lines and drain into the housing.
Note
Each transmitter is marked with a tag indicating the approvals. Install the transmitter according
to all applicable installation codes, and approval and installation drawings (see
Appendix B:
Product Certifications ). Verify that the operating atmosphere of the transmitter is consistent
with the hazardous locations certifications. Once a device labeled with multiple approval types
is installed, it should not be reinstalled using any of the other labeled approval types. To ensure
this, the approval label should be permanently marked to distinguish the approval type(s) used.
(1,500 °F)
Temperature
Oven
(1,000 °F)
Temperature
Oven
(482 °F)
Temperature
Oven
Housing Temperature
Rise Above
Ambient °C (°F)
60 (108)
50 (90)
40 (72)
0
30 (54)
20 (36)
10 (18)
3
4
5 6
7 8 9
Extension Length (in.)
815 °C
250 °C
540 °C
22
3.6