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1.6
Linearizing function
Because of its construction as described in the previous section, the PD 340 Flow Trans-
mitter is, by its very nature linear, even without any electronic compensation.
However, most of our customers prefer not to use anything smaller than 25 mm as a pipe
diameter, even for very low flow rates. Therefore, to further improve linearity, a special
compensation function has been developed and implemented within the 'Version 2' elec-
1
tronics module. Consequently, when this function is enabled
,, the PD 340 can now be
used even at very low flow rates, but still offering the same well-known high accuracy
measurement as normally experienced with higher flow rates.
During the flow calibration at the factory, the linearizing curve is calculated and downloaded
to the electronic module. For this reason, all new PD 340 Flow Transmitters will hold the
data needed by the linearizing function, when they are delivered as complete meters, i.e.
meterhead and electronic module. If one of the new electronic modules needs to be
mounted on a meter head with which it was not originally tested, and the linearizing func-
tion is to be used, data for the linearizing function can be downloaded to the electronic
module using a PC with VIGO version 5.6 or higher installed (valid for extended version
electronics only).
The graph below shows the linearizing curve for a specific flow transmitter. If this flow
transmitter measures the flow rate at 20% of full scale, this value will be compensated by
–0.01% of full scale.
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Enable/disable: Register E7, Dig. 5.
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Flow Transmitter, PD 340
Manual
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