P/N: 974153 |
Rev: 072016
|
ECO: 46503
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-23-
6 COMMISSIONING
There are two ways of commissioning the SPX transmitters. This can be done by utilizing the ZERO and
SPAN actuators or by HART Communications via a communicator connected to the pressure loop.
If the SPX is equipped with the optional HART Communications, it is not necessary to access the
zero/span actuators on the sensor.
If the transmitter is not equipped with HART then the zero/span actuators must be utilized. However,
Sections 6.3 through 6.8 and 6.11 may be skipped.
6.1 WHY A TRANSMITTER MUST BE REZEROED
The transmitter output must be nulled at zero pressure after installation when the machine has
stabilized at operating temperature. This is easy to understand why when considering the mechanical
properties of the sensor.
Depending on the orientation of the sensor, the weight of the diaphragm will have an effect on the
sensing diaphragm. The weight of the diaphragm will either increase or decrease deflection of the
diaphragm, creating a shift in the strain gage output that can appear as a positive or negative pressure.
There are some other effects that may affect the zero as well, such as torque, side loading, etc. For
more information contact Dynisco.
