Fig. 14. corrosion curve of the model ph18 enamel – Yokogawa PH18 Differential pH Sensor User Manual

Page 13

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IM 12B6J4-E-A

4. EXA PH202/FLXA21 or PH402/
PH450 INSTRUMENT

4-1. Set-up PH202/PH402
The EXA PH202/FLXA21 and PH402/PH450 are all
designed with dual matched high impedance inputs
which are necessary when using a pH probe like the
Model PH18 with both a measuring and a reference
electrode that are high impedance. To prepare the
Yokogawa instruments to work with the PH18 make
sure the input impedance jumpers are placed in the
correct positions:

PH202: See table 3-1 and fig. 3-8 on page
3-7 in the PH202 Instruction Manual
(IM 12B6C3-E-H) for jumper positions.
FLXA21: See fig. 3.11 on page 3-8 in the FLXA21
Instruction Manual (IM 12A01A02-01E) for
jumper positions.
PH402: See figure 3-9a on page 3-8 in the
Instruction Manual (IM 12B6B3-E-H) for
jumper positions.
PH450: See table 3-1 and figure 3-9a on page 12 in
the PH450 Instruction Manual
(IM 12B07C05-01E) for jumper positions.

4-2. Set-up PH202 and PH402
Since the Model PH18 has high impedances for both
the measuring and the reference elements, the high
impedance check functions (Service Codes 03 & 04)
must be set up according to the procedures outlined
in Section 5.3.1 in either the PH202 or the PH402
Manual. The Calibration check also needs to be
changed. Here you are instructed to set: The
Calibration check also needs to be changed. Here you
are instructed to set:

Service Code 03:
Change settings from 1.1.1 to 1.0.1 by using the ^ and
> keys. Low limit 1 Megohm. High limit 1 Gigaohm.

FIG.13 Connection diagram WU18 for
PH202/FLXA21 and PH402/PH450

FIG.14 Corrosion curve of the Model
PH18 Enamel

Service Code 04:
Change settings from 0.0.1 to 1.0.1 by using the ^ and
> keys. Low limit 1 Megohm. High limit 1 Gigaohm.

Service Code 05:
Change settings from 1.1 to 0.1 by using the ^ and
> keys. This disables the As. Pot. check which is not
appropriate for the PH18 system.

Once the jumpers and impedance Service Codes (03
& 04), Calibration Check (05) and Temperature element
have been set correctly, wire the probe cable to the
instrument as shown in Fig. 13.

For the FLXA21/PH450
Since the Model PH18 has high impedances for
both the measuring and the reference elements, the
impedance setting must be set up to reflect dual high
impedance according to the procedures outlined in
Section 5-6 in the PH450 or in Section 5.2.5in the
FLXA21 Manual. The Calibration check also needs to
be changed. Here you are instructions to set:

Impedance Settings:
Select the Execute Wrench from the Main Display.
Select Commissioning Measurement Setup

Impedance Settings

Ensure that Input 1 and Input 2 are set to High
Press the Home key to return to measuring mode.
Once the jumpers and impedance Settings have
been changed correctly, wire the probe cable to the
instrument as shown in Fig. 13.

Power wiring instructions are located in the respective
instrument manuals:

PH202: See section 3-4-3 on page 3-6 in the PH202
Instruction Manual (IM 12B6C3-E-H).
FLXA21: See section 3.3 on page 3-4 in the FLXA21
Instruction Manual (IM 12A01A02-01E).
PH402: See section 3-3-3 on page 3-5 in the PH402
Instruction Manual (IM 12B6B3-E-H).
PH450: See section 3-3-3 on page 10 in the PH450
Instruction Manual (IM 12B07C05-01E).

ENGLISH

IM 12B6J4-ED-H

4-1. Set-up
The EXA PH202 and PH402 are both
designed with dual matched high
impedance inputs which are necessary
when using a pH probe like the Model PH
18 with both a measuring and a reference
electrode that are high impedance. To
prepare the EXA instrument to work with
the PH18 make sure the input impedance
jumpers are placed in the correct positions:

PH202: See table 3-1 and fig. 3-8 on

page 3-7 in the PH202 Instruction
Manual (IM 12B6C3-E-H) for
jumper positions.

PH402: See figure 3-9a on page 3-8 in the

PH402 Instruction Manual
(IM 12B6B3-E-H) for jumper
positions.

Since the Model PH18 has high impedan-
ces for both the measuring and the
reference elements, the high impedance
check functions (Service Codes 03 & 04)
must be set up according to the procedures
outlined in Section 5.3.1 in either the PH202
or the PH402 Manual.
The Calibration check also needs to be
changed. Here you are instructed to set:

Service Code 03:
Change settings from 1.1.1 to 1.0.1 by
using the ^ and > keys.
Low limit 1Megohm. High limit 1 Gigaohm.

Service Code 04:
Change settings from 0.0.1 to 1.0.1 by
using the ^ and > keys.
Low limit 1Megohm. High limit 1 Gigaohm.

Service Code 05:
Change settings from 1.1 to 0.1 by using
the ^ and > keys. This disables the As.
Pot. check which is not appropriate for the
PH18 system.

Once the jumpers and impedance Service
Codes (03 & 04), Calibration Check (05)
and Temperature element have been set
correctly, wire the probe cable to the
instrument as shown in Fig. 13. Power
wiring instructions are located in the
respective instrument manuals:

PH202: See section 3-4-3 on page 3-6 in

the PH202 Instruction Manual
(IM 12B6C3-E-H).

PH402: See section 3-3-3 on page 3-5 in

the PH402 Instruction Manual
(IM 12B6B3-E-H).

Fig. 13 Connection diagram WU18 for

PH402 and PH202

4. EXA PH202 OR PH402 INSTRUMENT

4 6

Model PH18

sensor

measure

screen

reference

liquid

earth

temperature

0 1 2 4 6 8 10 12 14

140

120

100

NOT RESISTANT

RESISTANT

pH of sample

Measuring range

Fig. 14. Corrosion curve of the Model
PH18 Enamel