Yokogawa EJX440A - Manual (Page 39)

<3. Operation>
3-29
IM 01C25T01-01E
3.5.17 Capillary Fill Fluid Density
Compensation
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
compensating constant K (%/°C) with the measured
ambient temperature at the capsule module.
Compensated output = output + K × Tamb
(1) Temperature Compensation Mode Setup
When using this function, set T.Z. Cmp mode
to ON to enable or OFF to disable. To set to ON,
follow the procedure below.
F0351.ai
(ENTER)
EJX:
T.Z. Cmp mode
Off
Off
On
HELP DEL ESC ENTER
Select On, and press ENTER
(F4).
1. Device setup
4. Detailed setup
2. Signal condition
T.Z. Cmp menu
1. T.Z. Cmp mode
Example: Set the temperature compensation mode to ON.
EJX:
T.Z. Cmp menu
1 T.Z. Cmp mode On
2 Temp Zero
HELP SEND HOME ENTER
Press SEND (F2) to send the data
to the transmitter, then check to
confirm that disappears.
(SEND)
SEND
1
2
(2) Zero Shift Compensation Setup
Obtain the K compensating value from the
equation (a) below, and enter the value to Temp
Zero.
K= ×100.............. (a)
– h×B
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
(+)
 EJX118A
F0352.ai
h
h
L
L
H
Transmitter
Transmitter
0
(+)
(–)
 EJX438A
Note: When the transmitter is positioned lower than the
diaphragm seal part, the value of “h” must have a
negative sign (–).