Setra System Model 230 - Manual (Page 8)

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4.0 calIBratIon
The 230 transducer is factory calibrated and should require no field adjustment. Whenever possible,
any zero and/or span offsets should be corrected by software adjustment in the user’s control system.
However, zero and span adjustments are made by removing the cover on the top of the 230 and the
6-32 seal screws in the plastic terminal block. Be sure to reinstall seal screws after zero and/or span
adjustments. Current output transducers (4-20 mA) are factory calibrated using a 250 ohm load at 24
VDC. Zero and span adjustments are approximately 300 mV (for voltage units) and ±1.0 mA (for current
units), individually.
The 230 Series is calibrated with the diaphragm in the vertical position (pressure ports horizontal). For
use in other orientations, position the unit and adjust the zero by following the calibration procedure in
the previous section.
Optimal results will be achieved by using the factory calibrated position. The 230 position effects is as
follows (pressure ports in vertical plane): ±.5D, ±1D, 1D, 2D ranges. ±1% per g for all other standard
ranges. There is a negative output shift with the high pressure port facing up and a positive shift in the
output with the high pressure port facing down.
4.1 Voltage output Zero adjustment
While monitoring the voltage between the positive output (OUT) and common, and with both pressure
ports open to atmosphere, the zero may be adjusted. For unidirectional pressure ranges, turn the zero
adjustment screw until a reading of 0.05 VDC (±25 mV for 0-5 VDC or ±50 mV for 0-10 VDC output) is
achieved. For bidirectional pressure ranges, set zero to 2.550 VDC (±25 mv) for 0-5 VDC output or 5.050
VDC (±50 mV) for 0-10 VDC output.
4.2 Voltage output span adjustment
Complete the zero adjustment before setting span.)
Span or full scale output adjustments should only be performed by using an accurate pressure standard
(electronic manometer, digital pressure gage, etc.), with at least comparable accuracy to the 230 series
(±0.25% full scale). With the full range pressure applied to the high pressure port (reference open to
atmosphere), adjust output to 5.050 (±25 mV) or 10.050 VDC (±50 mV)
Example 1: Unidirectional pressure range of 0 to 1 PSI
Apply 1 PSI, adjust output to 5.050 VDC (or 10.050 VDC)
Example 2: Bidirectional pressure range of ±.5 PSI
Apply .5 PSI, adjust output to 5.050 VDC (for 10.050 VDC)