SMAR ld301, Инструкция по эксплуатации и техническому обслуживанию

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LD301- Operation and Maintenance, Instruction manual
3.6
This calibration procedure is also recommended for zero suppression or elevation in
those cases where the instrument installation results in a residual measurement in
relation to a certain reference. This is the specific case of the wetted tap.
Engineering Unit Selection
Transmitter LD301 includes a selection of engineering units to be used in measurement
indication.
CONVERSION
FACTOR
NEW UNITS
RECOMMEND
RANGE
1.00000 Inches H
2
O at 20
º
C 1, 2,3 & 4
0.0734241 Inches Hg at 0
º
C all
0.0833333 Feet H
2
O at 20
º
C all
25.4000 Millimeters H
2
O at 20
º
C 1 & 2
1.86497 Millimeters Hg at 0
º
C 1, 2, 3 & 4
0.0360625 Pound/square inch - psi 2, 3, 4, 5 & 6
0.00248642 Bar 3, 4, 5 & 6
2.48642 Millibar 1, 2, 3 & 4
2.53545 gram/square centimeter 1, 2, 3 & 4
0.00253545 kilogram/square centimeter 3, 4, 5 & 6
248.642 Pascal 1
0.248642 KiloPascal 1, 2, 3 & 4
1.86497 Torr at 0
º
C 1, 2, 3 & 4
0.00245391 Atmosphere 3, 4, 5 & 6
0.000248642 MegaPascal 4, 5 & 6
0.998205 inches of water at 4
º
C 1, 2, 3 & 4
25.3545 Millimeters of water at 4
º
C 1 & 2
Table 3.1 - Available Pressure Units
For pressure measurements, the LD301 includes an option list with the most common
units. The internal reference unit is inH
2
O @20
o
C; should the desired unit be other than
this one, it will be automatically converted using conversion factors included in Table
3.1.
As the LD301 uses a 4 ½ digit display, the largest indication will be 19999. Therefore,
when selecting a unit, make sure that it will not require readouts greater than this limit.
For User reference, Table 3.1 presents a list of recommended sensor ranges for each
available unit.
In applications where the LD301 will be used to measure variables other than pressure
or in the cases where a relative adjustment has been selected, the new unit may be
displayed by means of the User Unit feature. This is the case of measurements such
as level, volume, and flow rate or mass flow obtained indirectly from pressure
measurements.
The User Unit is calculated taking the working range limits as a reference, that is,
defining a value corresponding to 0% and another corresponding to 100% of the
measurement:
0% - Desired readout when the pressure is equal to the Lower Value (PV% = 0%,
or transmitter mode output equal to 4 mA).
100% - Desired readout when the pressure is equal to the Upper Value (PV% =
100%, or transmitter mode output equal to 20 mA).
The user unit may be selected from a list of options included in the LD301 . Table 3.2
makes it possible to associate the new measurement to the new unit so that all
supervisory systems fitted with HART

protocol can access the special unit included in
this table. The user will be responsible for the consistency of such information. The
LD301 cannot verify if the values corresponding to 0% and 100% included by the user
are compatible with the selected unit.
NOTE:
In most applications with wetted taps, indication is usually expressed as a percentage.
Should readout in engineering units with zero suppression be required, it is
recommended to use the User Unit feature for such conversion.