Operation And Maintenance; Checking The Cell; Calibration Of The Cell; Cleaning Of The Cell - YOKOGAWA SC4A Bedienungsanleitung

3. OPERATION AND MAINTENANCE

3-1. Checking the cell

If a fault occurs, first check the cell for visi-
ble damage. If damage is not apparent,
check the cell resistances measuring
between the cable connections.
a. 11 and 12 (or connector pins 1 and 2)
b. 11 and 13 (or connector pins 1 and 3)
c. 12 and 13 (or connector pins 2 and 3)
d. 12 and 15 (or connector pins 4 and 5)
e. 15 and 16 (or connector pins 5 and 6)
f. 13 and 14 (or connector pins 3 and 4)
g. 13 and 15 (or connector pins 3 and 5)
Celltype a b c d
SC4A Pt1000 > 100 > 100 > 100
value MΩ MΩ MΩ
If the cell has become fouled resistance will
be developed across the electrodes. These
resistances can be measured as shown in
fig. 3-1 by making contact directly with the
electrode and the relevant pin of the con-
nector.

3-2. Calibration of the cell

The cell constant is determined in laborato-
ry conditions. It is possible that slight varia-
tions in the cell constant may occur depen-
dant on the installation. This possible error
can be corrected by recalibrating with a
solution of known conductivity value
(according to DIN 53779).
NOTES:
The specific conductivity value of the solu-
tion of known value must be near the value
of the liquid to be measured. Specific con-
ductivity is highly temperature dependent,
therefore in the above calibration procedure
the temperature of the cell and the liquid
should be allowed to equalise and should
be accurately measured with a calibrated
thermometer.

3-3. Cleaning of the cell

If the cell becomes fouled an insulating
layer may be formed on the electrodes and
consequently, an apparent increase in cell
constant may accur, giving a measuring
error. This error is:
(Rv)
2 •
(Rcel)
Where:
Rv = the resistance of the fouling layer
Rcel = the cell resistance.
Cleaning methods
e f g
0 0 >100
1. For normal applications hot water with
MΩ MΩ MΩ
domestic washing-up liquid added will
be effective.
2. For lime, hydroxides, etc. a 5...10%
solution of hydrochloric acid is recom-
mended.
3. Organic foulings (oils, fats, etc.) can be
easily removed with acetone.
4. For algae bacteria or moulds, use a
chlorinated solution (domestic bleach*).
* Never use hydrochloric acid and
domestic bleach simultaneously. The
liberation of the very poisonous gas
chlorine will result.

3-4. Spare parts list

Spare part nr. Description
K1500BE
K1542DK
K1542DG
K1542DH
K1542DJ
K1542DF
K1542CW
K1520EK
K1520EJ
K1542FC
K1542FF
K1542FE
7
x 100 %
O-ring set -PR
O-ring set -SA
Seal rings -SB1
Seal rings -SB2
Seal ring -SC1
1" Stainless steel
adapter
1" PVDF Adapter
Angled welding socket
15º
Straight weld in adapter
Welding clamp 1"
1/2
Welding clamp 1 "
Welding clamp 2"
IM 12D7J4-E/D/F-H