SMAR ld301, Инструкция по эксплуатации и техническому обслуживанию

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Programming Using Hand-held Terminal
3.7
VARIABLE UNITS
Pressure
inH2O 20 , InHg, ftH2O, mmH2O 20 , mmHg, psi, bar ,mbar, g/cm 2 , kg/cm 2 , Pa,
kPa, Torr, atm, MPa, in H2O 4 , mmH2O 4
Volumetric Flow
ft 3 /m, gal/m, I/min, Gal/m, m 3 /h, gal/s, l/s, MI/d, ft 3 /s, ft 3 /d, m 3 /s, m 3 /d, Gal/h,
Gal/d, ft
3
/h, m
3
/m, bbl/s, bbl/m, bbl/h, bbl/d, gal/h, Gal/s, I/h, gal/d
Velocity ft/s, m/s, m/h
Volume gal, liter, Gal, m 3 , bbl, bush, Yd 3 , ft 3 , In 3 , hl
Level ft, m, in, cm, mm
Mass gram, kg, Ton, lb, Sh ton, Lton
Mass Flow
g/s, g/min, g/h, kg/s, kg/m, kg/h, kg/d, Ton/m, Ton/h, Ton/d, lb/s, lb/m, lb/h,
lb/d
Density
SGU, g/m 3 , kg/m 3 , g/ml, kg/l, g/l, Twad, Brix, Baum H, Baum L, API, % Solw,
% Solv, Ball
Others cSo, cPo, mA, %
special 5 characters
Table 3.2 – Available User Units
Should a special unit other than those presented on Table 3.2 be required, the LD301
allows the user to create a new unit by entering up to 5 alphanumeric digits.
The LD301 includes an internal feature to enable and disable the User Unit.
Example : transmitter LD301 is connected to a horizontal cylindrical tank (6 meters long
and 2 meters in diameter), linearized for volume measurement using camber table data
in its linearization table. Measurement is done at the high-pressure tap and the
transmitter is located 250 mm below the support base. The fluid to be measured is
water at 20
° C.
Tank volume is: [(
π
.d
2
)/4].l = [(
π
.2
2
)/4]
π
.6 = 18,85 m
3
.
The wet tap shall be subtracted from the measured pressure in order to obtain the tank
level. Therefore, a calibration without reference shall be carried out, as follows:
In Calibration :
Lower = 250mmH
2
O
Superior = 2250 mmH
2
O
Pressure unit = mmH
2
O
In User Unit :
User Unit 0% = 0
User Unit 100% = 18.85
User Unit = m
3
When activating the User's Unit, LD301 it will start to indicate the new measurement.
TRANSFER FUNCTION FOR FLOW MEASUREMENT
The function can be used to linearize the measured pressure to, flow or volume. The
following functions are available:
SQRT - Square Root. Considering the pressure input X varying between 0 and 100%,
the output will be 10
√
x. This function is used in flow measurement with, e.g., orifice or
Venturi tube etc.
The Square Root has an adjustable cutoff point. Below this point the output is linear, if
the cutoff mode is bumpless with the differential pressure as indicated by the Figure 3.2.
If the cutoff mode is hard the output will be 0% below the cutoff point. The default value
for Cutoff is 6% of ranged pressure input. The maximum value for cutoff is 100%. Cutoff
is used to limit the high gain, which results from square root extraction on small values.
This gives a more stable reading at low flows.
In order to find the square root, the LD301 configurable parameters are: cutoff point
defined at a certain pressure expressed as % and the cutoff mode, hard or bumpless.