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Instruction Sheet HxpH pH Sensor
LIQ_MAN_ABR_HxpH March 2014
pH Sensors
Specications
pH Range: 2 to 12 (0 to 14 short periods)
Temperature: -10 to 135 °C (14 to 275 °F)
Maximum Pressure: 58 psig (600 Pa abs, 4 bar)
Wetted Materials: Glass and EPDM
Process connections:
Hx338: PG 13.5 thread
Hx348: none
Cable Connector: S7 connector plug, single pole or VP
Variopol connector
Cable Compatibility: any AS7 connector plug, single
pole; or VP Variopol connector
Compatible Mounting Accessory:
Hx338: Insertion or Retraction Mounting Assembly
Hx348: Pressurized Mounting Assembly
Figure 1. pH Sensors
WARNING
Do not exceed temperature and pressure limitations of 130 °C (266 °F) and 72 psig (600 kPa, 6 bar).
CAUTION
Internal electrolyte ll solution may cause skin or eye irritation.
WARNING
Before removing the sensor, be absolutely certain that the process pressure is reduced to 0 psig and the process temperature is
lowered to a safe level!
CAUTION
SENSOR/PROCESS APPLICATION COMPATIBILITY
The wetted sensor materials may not be compatible with process composition and operating conditions. Application
compatibility is entirely the responsibility of the user.
CAUTION
Hydrouoric acid and the mixture of Hydrochloric acid and thiourea is toxic and highly corrosive. Avoid skin contact, wear
protective gloves. Use only in a well ventilated area. Do not inhale fumes. In case of an accident, consult a doctor immediately.
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HxpH pH Sensor Instruction Sheet
March 2014 LIQ_MAN_ABR_HxpH
Storage
1. It is recommended that electrodes be stored in their original shipping containers until needed.
2. Do not store at temperatures below -5 °C (23 °F).
3. Electrodes should be stored with a protective cap containing KCI solution (PN 9210342).
4. For overnight storage, immerse the sensor in tap water or 4 pH buffer solution.
5. pH glass electrodes slowly deteriorate in storage. There is no specic expiration date. However the calibration
procedure described on page 4 should be followed to determine that the sensors calibrate properly.
Electrode preparation
1. Remove electrode from shipping container.
2. Remove the protective boot covering the electrode bulb.
3. Rinse away salt lm with clean water, then shake the electrode so that the internal solution lls the bulb, thus
removing any air trapped there.
Note
Do not allow lubricant coat electrode bulb or reference junction. If it does, wipe it clean before installation.
Installation
For sensor orientation, see Figure 3.
For wiring, see see Figures 4 through 10.
Figure 2. Hx338 Dimensional Drawing
Sensor
Part Number
Hx338-01 120 4.725
Hx338-02 225 8.859
Hx338-03 325 12.796
Hx338-04 400 15.749
Hx338-05 425 16.733
A Dimension
mm inch
VP 6.0 PLUG
SW17 FREE SPINNING PG 13.5 THREAD
VP 6.0 PLUG
VP 6.0 PLUG
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Instruction Sheet HxpH pH Sensor
LIQ_MAN_ABR_HxpH March 2014
Figure 3. Hx348 Dimensional Drawing
Figure 4. Sensor Orientation
Sensor
Part Number
Hx348-01 – 11/12 120 4.73
Hx348-02 – 11/12 150 5.91
Hx348-03 – 11/12 200 7.88
Hx348-04 – 11/12 250 9.85
A Dimension
mm inch
3
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HxpH pH Sensor Instruction Sheet
March 2014 LIQ_MAN_ABR_HxpH
Two Point Buffer Calibration
Select two stable buffer solutions, preferably pH 4.0 and 10.0 (pH buffers other than pH 4.0 and pH 10.0 can be used as
long as the pH values are at least two pH units apart).
Note
A pH 7 buffer solution reads a mV value of approximately zero, and pH buffers read approximately ±59.1 mV for each pH unit
above or below pH 7. Check the pH buffer manufacturer specications for mil livolt values at various temperatures since it may
affect the actual value of the buffer solution mV/pH value.
1. Immerse sensor in the rst buffer solution. Allow sensor to equilibrate to the buffer temperature (to avoid errors
due to temperature differences between the buffer solution and sensor temperature) and wait for reading to
stabilize. Value of buffer can now be acknowledged by analyzer/transmitter.
2. Once the rst buffer has been acknowledged by the analyzer/transmitter, rinse the buffer solution off of the sensor
with distilled or deionized water.
3. Repeat steps 1 and 2 using the second buffer solution.
4. The theoretical slope value, according to the Nernst equation for calculating pH, is approximately 59.17 mV/pH.
Over time the sensor will age, both in the process and in storage, and will result in reduced slope values. To ensure
accurate readings, it is recommended that the electrode be replaced when the slope value falls below 47 to
49 mV/pH.
Recommended pH Sensor Standardization
For maximum accuracy, the sensor can be standardized on-line or with a process grab sample after a buffer cali bration has
been performed and the sensor has been conditioned to the process. Standardization accounts for the sensor junction
potential and other interferences. Standardization will not change the sensor’s slope but will sim ply adjust the analyzer’s
reading to match that of the known process pH.
Maintenance
Electrodes should respond rapidly. Sluggishness, offsets, and erratic readings are indicators that the electrodes may
need cleaning or replacement.
1. To remove oil deposit, clean the electrode with a mild non-abrasive detergent.
2. To remove scale deposits, soak electrodes for 30 to 60 minutes in a 5% hydrochloric acid solution.
3. Temperature effect on life expectancy: If glass electrode life expectancy is 100% @ 25 °C (77 °F), then it will be
approximately 25% @ 80 °C (176 °F), and approximately 5% @ 120 °C (248 °F).
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Instruction Sheet HxpH pH Sensor
LIQ_MAN_ABR_HxpH March 2014
Figure 5. VP 6.0 Cable Description, PN 23645-06 and
23645-07
Figure 7. Wiring to 1055-22-32
Figure 6. Wiring to 54, 54e, 81, 3081, 4081, 5081, and
remote junction box PN 23555-00
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HxpH pH Sensor Instruction Sheet
March 2014 LIQ_MAN_ABR_HxpH
Figure 8. Wiring to 1055-10-22-32
Figure 9. Wiring to Xmt-P-HT-10
If there is no temperature compensation (RTD), then install a 100-ohm resistor between TB1-1 and TB1-3, and install a jumbper between TB1-1 and TB1-2.
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Instruction Sheet HxpH pH Sensor
LIQ_MAN_ABR_HxpH March 2014
Figure 10. Wiring to Xmt-P-HT-10 (Panel Mount)
If there is no temperature compensation (RTD), then install a 100-ohm resistor between TB1-1 and TB1-3, and install a jumper between TB1-1 and TB1-2.
Figure 11. Wiring Drawing For Hx338 and Hx348 with S7 Connector
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HxpH pH Sensor Instruction Sheet
March 2014 LIQ_MAN_ABR_HxpH
Rev. H
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