Emerson Rosemount 372 User manual

Rosemount™ 372
HF Resistant pH sensor
uick Start Guide
00825-0100-3372
Rev. AA
May 2019

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Emerson designs, manufactures and tests its products to meet many national and international
standards. Because these sensors are sophisticated technical products, you MUS properly install,
use, and maintain them to ensure they continue to operate within their normal specifications. he
following instructions MUS be adhered to and integrated into your safety program when installing,
using, and maintaining Rosemount products. Failure to follow the proper instructions may cause
any one of the following situations to occur: loss of life; personal injury; property damage; damage
to this sensor; and warranty invalidation.
• Read all instructions prior to installing, operating, and servicing the product.
• If you do not understand any of the instructions, contact your Emerson representative
for clarification.
• Follow all warnings, cautions, and instructions marked on and supplied with the product.
• Inform and educate your personnel in the proper installation, operation, and mainte
nance of the product.
• Install your equipment as specified in the Installation Instructions of the appropriate
Instruction Manual and per applicable local and national codes. Connect all products to
the proper electrical and pressure sources.
• o ensure proper performance, use qualified personnel to install, operate, update,
program, and maintain the product.
• When replacement parts are required, ensure that qualified people use replacement
parts specified by Emerson. Unauthorized parts and procedures can affect the product's
performance, place the safe operation of your process at risk, and VOID YOUR
WARRAN Y. hird-party substitutions may result in fire, electrical hazards, or improper
operation.
• Ensure that all equipment doors are closed and protective covers are in place, except
when maintenance is being performed by qualified persons, to prevent electrical shock
and personal injury.
he information contained in this document is subject to change without notice.
Essential Instructions
Read this page before proceeding!
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
Before removing the sensor, be absolutely certain the process pressure is reduced to 0 psig and the process
temperature is at safe level.
CAUTION
1. All pH/ORP sensors have a plastic enclosure which must only be cleaned with a damp cloth to avoid the
danger due to a build up of an electrostatic charge.
2. All pH/ORP sensor models are intended to be in contact with the process fluid and may not meet the
500V r.m.s. a.c. test to earth.
This must be taken into consideration at installation.
Special Conditions for Safe Use
CAUTION

Physical access
Unauthorized personnel may potentially cause significant damage to and/or misconfiguration of end users’
equipment. This could be intentional or unintentional and needs to be protected against.
Physical security is an important part of any security progam and fundamental to protecting your system.
Restrict physical access by unauthorized personnel to protect end users’ assets. This is true for all systems
used within the facility.
WARNING

Contents
Section 1: Specifications
1.1 Specifications ......................................................................................................1
1.2 Ordering Information ..........................................................................................2
Section 2: Installation
2.1 Unpacking and Inspection ...................................................................................3
2.2 Storage................................................................................................................3
2.3 Electrode Preparation..........................................................................................3
Section 3: Wiring
3.1 Wiring for Rosemount 372 ..................................................................................5
Section 4: Calibration and Maintenance
4.1 wo Point Buffer Calibration................................................................................9
4.2 Recommended pH Sensor Standardization .........................................................9
4.3 Maintenance .......................................................................................................9
uick Start Guide Table of Contents
00825-0100-3372 May 2019
Table of Contents i

Table of Contents uick Start Guide
May 2019 00825-0100-3372
ii Table of Contents

Section 1: Specifications
Specifications 1
uick Start Guide Specifications
00825-0100-3372 May 2019
Table 1-1: Rosemount 372 HF resistant pH sensor specifications
Materials of construction
Ultem, Viton, glass, Kynar
Process connections
3/4 in. forward (insertion) and 1 in. reverse (submersion) M PT
Insertion depth
2.2 in. to 8.3 in.
Measured range
0 to 12 pH (0-14 pH if no sodium ions are present)
Pressure range
-13 to 135 psig (6.9 to 1035 kPa abs)
Temperature range
-5 to 50 °C [23 to 122 °F] (100 °C [212 °F] if no fluoride ions are present)
Temperature compensation
Pt 100
Weight/shipping weight
0.4 kg/0.9 kg (1 lb/ 2 lb)
pH glass type
Hemispherical
Glass diameter
7.8mm
Glass impedance
Less than 400 M @ 25 °C
Acidic error
Less than .01 pH in 1.0M HCl @ 0.0pH
Reference type
Double junction with saturated KCL in cross-linked polymer
1.1 Specifications

2 Specifications
Specifications uick Start Guide
May 2019 00825-0100-3372
1.2 Ordering Information
Table 1-2: Rosemount 372 HF resistant pH sensor ordering information
Model Sensor type
372 pH/ORP Sensor
Preamplifier/cable
01 25 ft. cable with integral preamplifier
02 15 ft. cable without integral preamplifier
Typical Model Number: 372-01

Installation 3
Section 2: Installation
uick Start Guide Installation
00825-0100-3372 May 2019
2.1 Unpacking and Inspection
Inspect the outside of the carton for any damage. If damage is detected, contact the carrier
immediately. Inspect the instrument and hardware. Make sure all items in the packing list are
present and in good condition. otify the factory if any part is missing.
2.2 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 KCl solution (P 9210342).
4. For overnight storage, immerse the sensor in tap water or a 4 pH buffer solution.
5. A pH glass electrode has a limited shelf life of one year.
2.3 Electrode Preparation
1. Remove electrode from shipping container.
2. Remove the protective boot covering the electrode bulb.
3. Rinse away salt film with clean water, then shake the electrode so that the internal
solution fills the bulb, thus removing any air trapped there.
Figure 2-1 Sensor dimensions
Do not allow lubricant to coat electrode bulb or reference junction. If it does, wipe it clean before
installation.
NOTICE

4 Installation
Installation uick Start Guide
May 2019 00825-0100-3372
Figure 2-2 Sensor orientation

Wiring 5
uick Start Guide Wiring
00825-0100-3372 May 2019
3.1 Wiring for Rosemount 372
For additional wiring information on this product, including sensor combinations not shown here,
please refer to the Liquid Transmitter Wiring Diagrams.
Section 3: Wiring
Figure 3-1: Rosemount 372-01 to Rosemount 1056/56/1057 Transmitter Wiring

6 Wiring
Wiring uick Start Guide
May 2019 00825-0100-3372
Figure 3-2: Rosemount 372-01 to Rosemount 1066 Transmitter
Figure 3-3: Rosemount 372-01 to Rosemount 5081 Transmitter Wiring

Wiring 7
uick Start Guide Wiring
00825-0100-3372 May 2019
Figure 3-4: Rosemount 372-02 to Rosemount 1056/56/1057 Transmitter Wiring
Figure 3-5: Rosemount 372-02 to Rosemount 1066 Transmitter Wiring

8 Wiring
Wiring uick Start Guide
May 2019 00825-0100-3372
Figure 3-6: Rosemount 372-02 to Rosemount 5081 Transmitter Wiring

4.1 Two Point Buffer Calibration
Select two stable buffer solutions, preferably pH 4.0 and 7.0 (pH buffers other than pH 4.0 and
pH 7.0 can be used as long as the pH values are at least two pH units apart).
1. Immerse sensor in the first 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 transmitter.
2. Once the first buffer has been acknowledged by the 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 ernst 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.
4.2 Recommended pH Sensor Standardization
For maximum accuracy, the sensor can be standardized online or with a process grab sample after
a buffer calibration 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 simply adjust the transmitter’s reading
to match that of the known process pH.
4.3 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).
Section 4: Calibration and Maintenance
Calibration and Maintenance 9
uick Start Guide Calibration and Maintenance
00825-0100-3372 May 2019
A pH 7 buffer solution reads a mV value of approx. zero, and pH buffers read approximately ± 59.1 mV for
each pH unit above or below pH 7. Check the pH buffer manufacturer specifications for millivolt values at
various temperatures since it may affect the actual value of the buffer solution mV/pH value.
NOTICE

00825-0100-3372
Rev. AA
May 2019
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