Yokogawa EJX440A - Manual (Page 28)

IM 01C25T03-01E 3-20
3. OPERATION
(20) Capillary Fill Fluid Density Compensa-
tion (E10: T.ZERO CMP, E11: TEMP
ZERO)
For transmitters with diaphragm seals, this function is
used to compensate the zero shift caused by the
ambient temperature effect on the capillary tubes.
The following equation indicates the relationship
between the calculated output value and the compen-
sating constant K (%/
ЊC) with the measured ambient
temperature at the capsule module.
Compensated output
ϭ
output
ϩ
K
ϫ
Tamb
(1) Temperature Compensation Mode Setup
(E10: T. ZERO CMP)
When using this function, set T. ZERO CMP to ON
to enable or OFF to disable. To set to ON, follow
the procedure below.
ESC
SET
E10:T.ZERO CMP
OFF
< OFF >
< ON >
OK FEED NO
SET
E10:T.ZERO CMP
ON
• Example: Set the temperature compensation
mode to ON.
Use the or key
to select ON.
Press the key twice to
enter the setting.
Press the (OK) key.
F0355.EPS
(2) Zero Shift Compensation Setup
(E11: TEMP ZERO)
Obtain the K compensating value from the equa-
tion(1) below.
K= – h
×
B ×
100 ................ (a)
Span
where,
B: Constant value of fill fluid (See Table A.)
span: |URV–LRV|
h: Distance from high pressure side to low
pressure side (m)
EJX118A: Distance from high side of
diaphragm seal to low side of diaphragm seal.
EJX438A: Distance from diaphragm seal (high
side) to position of transmitter (low side).
Transmitter
L
h
0
H
( ϩ )
᭹ EJX118A
F0357.EPS
h
h
L
L
H
Transmitter
Transmitter
0
( ϩ )
( Ϫ )
᭹ EJX438A
Note: When the transmitter is positioned lower than the
diaphragm seal part, the value of “h” must have a
negative sign ( Ϫ ).
Enter “–0.149.”
Press the key twice to
enter the setting.
F0358.EPS
ESC
SET
E11:TEMP ZERO
0.000 %/degC
- 00.149
CLR
OK
SET
E11:TEMP ZERO
-0.149 %/degC
NO FEED
K
ϭϪ
(
ϩ
3)
ϫ
0.00745
Ϭ
15
ϫ
100
ϭϪ
0.149
Press the (OK) key.
• Example: Enter K value obtained from the
equation (a). A value having up to 3
decimal places may be specified.
When h
ϭϩ
3 m, Fill fluid code A, span
ϭ
15 kPa,
Note 1: The function is performed using in a built-in temperature
sensor in the transmitter body. The temperature deviation
between the transmitter body and capillaries should be
minimized to achieve optimal performance of the function.
Note 2: When the span changes, reenter the newly obtained value of
K to E11: TEMP ZERO.
Table A. Constant value [B] of fill fluid
T0308.EPS
Fill fluid
A, C B D E
code
mmH
2 O 0.76 0.87 1.45 0.75
kgf/cm 2 0.000076 0.000087 0.000145 0.000075
kPa 0.00745 0.00853 0.01422 0.00736
mBar 0.07453 0.08532 0.14220 0.07355
atm 0.000074 0.000084 0.000140 0.000073
inH 2 O 0.02992 0.03425 0.05709 0.02953
psi 0.00108 0.00124 0.00206 0.00167
mmHg 0.05592 0.06401 0.10669 0.05518 Constant v
alue [B]
Note 3: Select the unit of constant value of [B] from the actual unit
used for the transmitter in operation.