Yokogawa FU20/PH20 All-in-One pH/ORP Sensor - Manual (Page 11)

IM 12B6J3-02E-E
9
6. MODEL CODES
The FU20 has a reference system of
Saturated Silver/Silver Chloride and the
values are given in the following table as
function of the measurement function ( 4.2)
Function ORP pH comp. ORP rH
pH= 1,68 403
88 23,6
pH= 4,01 265 88 23,6
pH= 6,87 96 88 23,6
pH= 7,00 88 88 23,6
The accuracy of the standard values is
approximately +/- 10 mV.
5-3. Maintenance
All pH sensors require routine maintenance
to keep the measuring elements clean and
functioning. Depending on the process,
different cleaning solutions may be required.
EXAMPLES:
1. Deposits of limes, hydroxides or
carbonates can be removed by immersing
the sensor in a solution containing dilute
hydrochloric acid (5% is recommended).
Afterwards rinse with water.
2. Deposits of oil and fat can be removed
with hot water with a detergent. When
the results are unsatisfactory, a mild
(carbonate based) abrasive can be used.
3. Protein deposits should be removed with
a protein enzymatic solution. For instance
a solution containing 8.5ml concentrated
hydrochloric acid and 10 grams
of pepsin in 1 liter of water will do.
After cleaning the probe is reinserted into the
process by following the reverse procedure.
NOTE:
Avoid using non-polar solvent like tri-chloro
ethylene, toluene or hexane. Cleaning with
iso-propanol or methanol is acceptable.
The non-polar solvents will break up the
gel-layer on the glass bulb and requires that
the electrode to be soaked in water
for at least 12 hours before functioning
normally again. The Teflon (PTFE)
diaphragm of the sensor can sometimes be
regenerated by putting it in hot (60 to 80°C)
3 molar Potassium Chlorine (KCl) solution
and letting it cool to room temperature.
This procedure clears the junction of
process material and then “draws” the
conductive (KCl) back into the junction.
Model Code Suffix Code Option Description
FU20 Wide body sensor
Cable length -03 3 mtr
-05 5 mtr
-10 10 mtr
-20 20 mtr
-VP Vario Pinconnector (no cable)
Temp. element -T1 Pt1000
Model -NPT Dome shape model
-FSM Flat surface model
Options /HCNF Hastelloy cleaning system
/FPS Adapter F*40 from noryl
/NSS 1” NPT adapter, SS (316L)
/NTI 1” NPT adapter, Titanium
/BSS 1” BSP adapter, SS (316L)
/BTI 1” BSP adapter, Titanium