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Reference Manual
00809-0200-4728, Rev SA
Safety Instrumented Systems (SIS) Certification
July 2018
Safety Instrumented Systems (SIS) Certification
7.3 Installation
Installations are to be performed by qualified personnel. No special installation is required in addition to
the standard installation practices outlined in this document. Always ensure a proper seal by installing
the electronics housing cover(s) so that metal contacts metal.
The loop should be designed so the terminal voltage does not drop below 12 Vdc when the transmitter
output is 24.5 mA.
Environmental limits are available in the Rosemount 644 Temperature Transmitter
product page.
7.4 Configuration
Use any HART capable configuration tool or the optional Local Operator Interface (LOI) to communicate
with and verify the initial configuration or any configuration changes made to the Rosemount 644 prior
to operating in Safety Mode. All configuration methods outlined in Section 2 are the same for the safety
certified Rosemount 644 Transmitter with any differences noted.
Software lock must be used in order to prevent unwanted changes to the transmitter configuration.
Note
Transmitter output is not safety-rated during the following: Configuration changes, Multidrop operation,
Simulation, Active calibrator mode, and loop tests. Alternative means should be used to ensure process
safety during transmitter configuration and maintenance activities.
7.4.1 Damping
User-adjustable damping affects the transmitter’s ability to respond to changes in the applied process.
The damping value + response time should not exceed the loop requirements.
If using a thermowell assembly, make sure to also take into account the added response time due to
thermowell material.
7.4.2 Alarm and saturation levels
DCS or safety logic solver should be configured to match transmitter configuration. Figure 7-1 identifies
the three alarm levels available and their operations values.
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