Yokogawa FU20/PH20 All-in-One pH/ORP Sensor - Manual (Page 6)

IM 12B6J3-E-H
2
2. GENERAL SPECIFICATIONS PH20
2-1. Measuring elements : pH glass electrode
: Silver chloride reference
: Solid platinum electrode
: Pt1000 temperature sensor.
2-2. Construction materials
Body
: PVDF
Earthing pin : Solid Platinum
O-ring : Viton
Reference junction : Porous PTFE
Cable : Coaxial with 4 extra leads
2-3. Functional specifications (at 25°C)
Isothermal point
: pH 7
Glass impedance : 200 M
Ω (nominal)
Reference system : Ag/AgCl with saturated KCl
Junction resistance : 1 to10 k
Ω
Temperature element : Pt1000 to IEC 751
Asymmetry potential : < 15 mV
Slope : > 96 % (of theoretical value)
NOTE:
The temperature sensor included in the PH20 is intended to provide indication and cell
compensation. The construction has not been tested to the pressure vessel standards
required for plant temperature control.
2-4. Dynamic specifications
Response time pH step (7 to 4)
: < 10 sec for 90%
Response time temp step (10°C) : < 3 min for 90 %
Stabilisation time (0.02 pH unit/ 10 s) : < 1 minute
2-5. Operating range
pH
: 0 to 14
Temperature : -10 to 100 °C (14 to 212 °F)
Pressure : 0 to 10 bar ( 0 to 145 PSIG)
Conductivity : > 50 µS/cm
Storage temperature : -30 to 50 °C (-22 to 122 °F)
NOTE:
Specifications should not be considered in isolation. For example the pH range can be 2-12
pH, where the measurement is at elevated temperatures. For advice about specific applica-
tions please contact your local sales office.
Pressure Effects on sensor mV
Conventional Sensor Pressure
potential (m V)
Tempress
-180
-200
-220
-240
-260
-280
-300
200 250 300
time (min)>
15
10
5
0
pressure (bar)
The erratic trend of the standard sensor shows
the progressive contamination of its reference
junction. The graph indicates between 0.1 to 0.4
pH error with the conventional sensor while the
readings from the Tempress are extremely sta-
ble.