Omega Engineering PH-2720-PA User Manual

User’s Guide

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www.omega.com

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PH-2720-PA

Preamplifier

OMEGAnet® Online Service Internet e-mail

www.omega.com [e-mail]

Servicing North America:

USA: One Omega Drive, P.O. Box 4047

ISO 9001 Certified Stamford CT 06907-0047

TEL: [phone] FAX: [phone]
e-mail: [e-mail]

Canada: 976 Bergar

Laval (Quebec) H7L 5A1
TEL: [phone] FAX: [phone]
e-mail: [e-mail]

For immediate technical or application assistance:

USA and Canada: Sales Service: 1-800-826-6342 / 1-800-TC-OMEGA

Customer Service: 1-800-622-2378 / 1-800-622-BEST
Engineering Service: 1-800-872-9436 / 1-800-USA-WHEN
TELEX: 996404 EASYLINK: 62968934 CABLE: OMEGA

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Mexico: En Español: [phone]-7803 e-mail: [e-mail]

FAX: [phone] [e-mail]

Servicing Europe:

Benelux: Postbus 8034, 1180 LA Amstelveen, The Netherlands

TEL: [phone] FAX: [phone]
Toll Free in Benelux: 0800 0993344
e-mail: [e-mail]

Czech Republic: Rudé armády 1868, 733 01 Karviná 8

TEL: [phone] FAX: [phone]
Toll Free: 0800-1-66342 e-mail: [e-mail]

France: 9, rue Denis Papin, 78190 Trappes

TEL: [phone] FAX: [phone]
Toll Free in France: 0800-4-06342
e-mail: [e-mail]

Germany/Austria: Daimlerstrasse 26, D-75392 Deckenpfronn, Germany

TEL: [phone] FAX: [phone]
Toll Free in Germany: 0800 639 7678
e-mail: [e-mail]

United Kingdom: One Omega Drive, River Bend Technology Centre

ISO 9002 Certified Northbank, Irlam, Manchester

M44 5EX United Kingdom
TEL: [phone] FAX: [phone]
Toll Free in United Kingdom: 0800-488-488
e-mail: [e-mail]

It is the policy of OMEGA to comply with all worldwide safety and EMC/EMI regulations that
apply. OMEGA is constantly pursuing certification of its products to the European New Approach
Directives. OMEGA will add the CE mark to every appropriate device upon certification.

The information contained in this document is believed to be correct, but OMEGA Engineering, Inc. accepts
no liability for any errors it contains, and reserves the right to alter specifications without notice.
WARNING: These products are not designed for use in, and should not be used for, patient-connected applications.

OMEGA PH-2720-PA pH/ORP Preamplifier Instructions

SAFETY INSTRUCTIONS FOR IN-LINE ELECTRODE INSTALLATION

1. Do not remove from pressurized lines.

2. Do not exceed maximum temperature/pressure specifications.

3. Wear safety goggles or face shield during installation/service.

4. Do not alter product construction.
Failure to follow safety instructions may result in severe personal injury!

1. Wiring

Preamplifier:
PH-2720-PA

pH
Electrodes:

PHE-3271
PHE-2716

Preamplifier:
PH-2720-PA

pH
Electrodes:

PHE-3271
PHE-2716

ORP
Electrodes:

ORE-2715
ORE-2717

Silver (earth ground)

Brown
Blue

Green
White
Red
Black

Silver (earth ground)

Red
Black

Green
Brown
White
Blue

• Use X1 gain selection

(mV Input)
(Iso. Gnd)
(T+)
(T-)
(V+)
(V-)

(#10) V+
(#11) V-
(#12) T+
(#13) Ain
(#14) ISO
(#14) ISO

7

6

8

4

10

ALARM 1

pH

2

0

OMEGA

PHCN-5700

pH CONTROLLER

RLY 1
RLY 2
RLY 3
RLY 4

pH

ENTER MOD

CAL RELAY OUTPUT

OMEGA

PHCN-90

Preamplifier:
PH-2720-PA

ALARM 2

12

14

ENTER

pH
Electrodes:

PHE-3271
PHE-2716

ORP
Electrodes:

ORE-2715
ORE-2717

Preamplifier:
PH-2720-PA

mV

TEMP

Silver (earth ground)

Brown
Blue

Black
Red
Green
White

Silver (earth ground)

Red
Black

Green
White
Brown
Blue

(mV Input)
(Iso. Gnd)
(V-)
(V+)
(T+)
(T-)

(#10) V+
(#11) V-
N/C
N/C
(#13) Ain
(#14) ISO

OMEGA

PHCN-5700

ORP CONTROLLER

RLY 1
RLY 2
RLY 3
RLY 4

ORP

ENTER MOD

CAL RELAY

OUTPUT

OMEGA

mV

ORCN-90

ORP

• Use X1 gain selection

Electrodes:

ORE-2715
ORE-2717

Technical Notes:

• Use 6-conductor shielded cable for cable extensions to 120 m (400 ft)

• Shield must be maintained through cable splice

2. Installation Fittings

Type Description

Plastic tees

PVC glue-on
saddles
(O-ring not
required)

Iron
strap-on
saddles

Consult OMEGA for additional fitting information.

• 0.5 to 4 in.

• PVC or CPVC

• Mounts via glue-on fittings

• 2 to 4 in., use 1-7/16 in. hole in pipe

• Align wedge arrows with saddle

arrows during assembly.

• 2 to 4 in., use 1-7/16 in. hole in pipe

Type Description
Carbon steel

weld-on
weldolets

• 2 to 4 in, use 1-7/16 in. hole in pipe

• Remove insert before welding

• Installed by certified welder only

Carbon steel
threaded tees

Universal
pipe adapter

• 0.5 to 2 in.

• Mounts on threaded pipe ends

• For existing pipe fittings 2 in. and up

• External 1-1/4 inch NPT male threads

for large pipes

3. Recommended Position

3/4 in. NPT OR
ISO 7/1-Rc 3/4
female threads

Customer supplied:

• 3/4 in. NPT nipple (male)

• J-box

• flex conduit

Customer supplied:

• 3/4 in. NPT threaded

C.

B.

D.

A.

pipe (A)

• J-box (B)

• Flex conduit (C)

• Quick release pipe
clamp (D)

• Tank flange (E)

B.

C.

A.

In-Line

• Vertical (0°) position optimum

• 4 fps or less for max. performance and sensor life

4. Installation

In-line Applications

Preamplifier

A. O-ring lubricant
recommended
(factory applied)

E.

2 in.

min.

Closed

tanks

-60°

0°

+60°

Process
pipe

Open

tanks

Caution: If liquid level is not constant, always ensure
liquid contact with electrode tip

Submersible Applications

1

C.

B. Align
marks

Hand
tighten

only!

2

Preamplifier

A. O-ring lubricant
recommended
(factory applied)

1

Customer
supplied
pipe

C.

B. Align
marks

2

Sealant

3/4 in. NPT or
ISO 7/1-Rc 3/4

Sealant

PH-31542-TC Sensor Cap
(purchased separately)

Fitting
inlet

3

Fill with
3 to 4 in.
of sealant

Attach 3/4 in. watertight pipe to the top of the preamplifier. Secure
the threaded connection to prevent any leakage. For additional
defense against possible accumulation of condensation at the back
seal area of the sensor, fill the lower 3-4 inches (75-100 mm) of
conduit or extension pipe with a flexible sealant such as silicone.

5. Accessories

503

PSI

BAR

50

75

25

122

167

77

25

2

75

5

1007

100

212

°F

°C

p

Part no.

PH-31542-TC

Description
Sensor

Material

PP

cap

FPP-1220-0021
FPP-1224-0021
FPP-1228-0021

Sensor O-ring,
2 required

Viton®
EPR
Kalrez

6. Specifications

PH-2720-PA pH/ORP Preamplifier

Housing material: CPVC
Compatible sensors: PHE-3271 Flat Surface pH Electrode

PHE-2716 Bulb pH Electrode
ORE-2715 Flat Surface ORP Electrode
ORE-2717 Bulb ORP Electrode

Input Impedance: >1011 Ω
Operating temp.: 0 to 80 °C
Gain: X1 (unity)
Input power: ±4.5 to ±8 VDC, dual supply
Current consumption: <1 mA, dual supply
Quality standard: CE

CAUTION!

When replacing O-rings, apply O-ring lubricant to sensor O-rings
prior to preamplifier/electrode assembly. Unlubricated O-rings
may score the preamplifier sealing surface.

PHE Series pH Electrodes - ORE Series ORP Electrodes

General Specifications

Wetted parts:
Sensor body: CPVC
O-rings: Viton®
Electrode junction: Porous UHMW polyethylene
Quality standard: CE

Maximum pressure/temperature ratings:

• 7 bar (100 psi) max. @ ≤65 °C (149 °F)

• 4 bar (58 psi) max. @ ≤85 °C (185 °F)

Dimensions:

Std.15 ft/

4.6 m cable

1.8 in./
46 mm

7. Preamplifier Troubleshooting

Procedure:
A. Install sensor adapter into preamplifier
B. With preamplifier and instrument connected, simulate pH 4, 7, and

10 and record displayed mV readings (right) and approximate
preamplifier response time between simulations.

C. Refer to table on next page for preamplifier troubleshooting tips.

3/4 in. NPT
female threads

3.6 in./
91 mm

SAFETY INSTRUCTIONS FOR IN-LINE ELEC­TRODE INSTALLATION

1. Do not remove from pressurized lines.

2. Do not exceed maximum temperature/pressure
specifications.

3. Do not install/service without following
installation instructions (see sensor manual).

4. Wear safety goggles and faceshield during
installation/service.

5. Do not alter product construction.

6. Failure to follow safety instructions could result
in severe personal injury!

Simulator Actual displayed

Input mV

4.00, +177 mV ________________________

7.00, 0 mV ________________________

10.00, -177 mV ________________________

Pream

lfier response time: ________________________

With simulator
connected

Error Condition

A) mV output stuck at
zero
B) mV output erratic
C) mV output stuck at

1.4 VDC

Possible Cause

A) Shorted input signal
B) Faulty preamplifier or wiring
C) Faulty preamplifier

Possible Remedy

A) Check preamplifier cable connections and shielding.
B) Verify preamplifier shield connections. Verify cable shield
wire has been maintained through each cable splice.
C) Replace preamplifier

Ok with
simulator
connected but
fails with
electrode

A) mV output stuck
near zero
B) mV output erratic
C) Output stuck at

1.4 VDC

A) Cracked electrode glass
B1) Poor contact between
electrode and preamplifier
connectors
B2) Fouled electrode
reference or aged electrode
B3) Ground loop
C) Faulty preamplifier

8. Electrode Maintenance and Cleaning

8.1 Maintenance

Variables can affect long term pH or ORP electrode life. For this
reason, a maintenance log is recommended for trend analysis. When
storing boxed sensors, lay the sensor flat to maximize hydration of the
glass surface. Keep the glass surface wet at all times. Soak the sensor
tip in pH 4.0 buffer during system maintenance intervals. In-line
applications should be plumbed with a depression (trap) which ensures
liquid is maintained around the sensor tip. If sensor dehydration has
occurred, soak the sensor tip in pH 4 buffer for 24 to 48 hours, then
visually inspect the electrode for surface cracks, swelling, or
discoloration.

8.2 Cleaning

Cleaning techniques vary depending on the type of coating present on
the glass electrode surface or reference junction.

A) Replace electrode
B1) Check contacts between electrode and preamplifier.
Contacts must be clean and dry.
B2) Clean electrode, see electrode manual
B3) Isolate electrode in test beaker. If output is stable, ground
loops may exist causing erratic behavior; isolate instrument
outputs (i.e. 4 to 20 mA, 0 to 5 VDC).
C) Replace preamplifier

• Hard coatings: can be chemically removed. Always use the least

harsh chemical which will remove the contaminant within two (2)
minutes without attacking the materials of construction. e.g. calcium
carbonate may be removed with a 5% HCL (muriatic acid) solution.

• Oily or Organic Coatings: can be removed with detergents or an

appropriate solvent that does not attack the materials of
construction e.g. isopropyl alcohol may be used but acetone must
be avoided to prevent damage to the CPVC sensor body.

• ORP electrode surface (platinum rod): can be gently sanded with

600 grit wet and dry silicone or carbide sandpaper, jewelers
rouge, crocus cloth, or very fine steel wool.

• Soft coatings: can be removed by vigorous stirring, or with

directed spray of an applicable detergent or solvent onto the glass
electrode surface. Chlorine bleach or mild detergent may be used
to remove soft coatings. Always rinse electrode tip in clean water
after cleaning.

WARNING!

When using chemicals or solvents care should be taken and
appropriate eye, face, hand, body, and/or respiratory
protection should be used.

WARRANTY/DISCLAIMER

OMEGA ENGINEERING, INC. warrants this unit to be free of defects in materials and workmanship for a
period of 13 months from date of purchase. OMEGA’s WARRANTY adds an additional one (1) month
grace period to the normal one (1) year product warranty to cover handling and shipping time. This
ensures that OMEGA’s customers receive maximum coverage on each product.

If the unit malfunctions, it must be returned to the factory for evaluation. OMEGA’s Customer Service
Department will issue an Authorized Return (AR) number immediately upon phone or written request.
Upon examination by OMEGA, if the unit is found to be defective, it will be repaired or replaced at no
charge. OMEGA’s WARRANTY does not apply to defects resulting from any action of the purchaser,
including but not limited to mishandling, improper interfacing, operation outside of design limits,
improper repair, or unauthorized modification. This WARRANTY is VOID if the unit shows evidence of
having been tampered with or shows evidence of having been damaged as a result of excessive corrosion;
or current, heat, moisture or vibration; improper specification; misapplication; misuse or other operating
conditions outside of OMEGA’s control. Components which wear are not warranted, including but not
limited to contact points, fuses, and triacs.

OMEGA is pleased to offer suggestions on the use of its various products. However,
OMEGA neither assumes responsibility for any omissions or errors nor assumes liability for any
damages that result from the use of its products in accordance with information provided
by OMEGA, either verbal or written. OMEGA warrants only that the parts manufactured by it
will be as specified and free of defects. OMEGA MAKES NO OTHER WARRANTIES OR
REPRESENTATIONS OF ANY KIND WHATSOEVER, EXPRESS OR IMPLIED, EXCEPT THAT OF
TITLE, AND ALL IMPLIED WARRANTIES INCLUDING ANY WARRANTY OF MERCHANTABILITY
AND FITNESS FOR A PARTICULAR PURPOSE ARE HEREBY DISCLAIMED. LIMITATION OF
LIABILITY: The remedies of purchaser set forth herein are exclusive, and the total liability of
OMEGA with respect to this order, whether based on contract, warranty, negligence,
indemnification, strict liability or otherwise, shall not exceed the purchase price of the
component upon which liability is based. In no event shall OMEGA be liable for
consequential, incidental or special damages.

CONDITIONS: Equipment sold by OMEGA is not intended to be used, nor shall it be used: (1) as a “Basic
Component” under 10 CFR 21 (NRC), used in or with any nuclear installation or activity; or (2) in medical
applications or used on humans. Should any Product(s) be used in or with any nuclear installation or
activity, medical application, used on humans, or misused in any way, OMEGA assumes no responsibility
as set forth in our basic WARRANTY / DISCLAIMER language, and, additionally, purchaser will indemnify
OMEGA and hold OMEGA harmless from any liability or damage whatsoever arising out of the use of the
Product(s) in such a manner.

RETURN REQUESTS/INQUIRIES

Direct all warranty and repair requests/inquiries to the OMEGA Customer Service Department. BEFORE
RETURNING ANY PRODUCT(S) TO OMEGA, PURCHASER MUST OBTAIN AN AUTHORIZED RETURN
(AR) NUMBER FROM OMEGA’S CUSTOMER SERVICE DEPARTMENT (IN ORDER TO AVOID
PROCESSING DELAYS). The assigned AR number should then be marked on the outside of the return
package and on any correspondence.

The purchaser is responsible for shipping charges, freight, insurance and proper packaging to prevent
breakage in transit.

FOR

WARRANTY RETURNS, please have the
following information available BEFORE
contacting OMEGA:

1. Purchase Order number under which the

product was PURCHASED,

2. Model and serial number of the product under

warranty, and

3. Repair instructions and/or specific problems

relative to the product.

OMEGA’s policy is to make running changes, not model changes, whenever an improvement is possible. This affords
our customers the latest in technology and engineering.

OMEGA is a registered trademark of OMEGA ENGINEERING, INC.
© Copyright 2000 OMEGA ENGINEERING, INC. All rights reserved. This document may not be copied, photocopied,

reproduced, translated, or reduced to any electronic medium or machine-readable form, in whole or in part, without the
prior written consent of OMEGA ENGINEERING, INC.

FOR NON-WARRANTY REPAIRS,

consult OMEGA
for current repair charges. Have the following
information available BEFORE contacting OMEGA:

1. Purchase Order number to cover the COST of

the repair,

2. Model and serial number of the product, and

3. Repair instructions and/or specific problems

relative to the product.

Where Do I Find Everything I Need for

Process Measurement and Control?

OMEGA…Of Course!

Shop online at www.omega.com

TEMPERATURE



Thermocouple, RTD & Thermistor Probes, Connectors, Panels & Assemblies



Wire: Thermocouple, RTD & Thermistor



Calibrators & Ice Point References



Recorders, Controllers & Process Monitors



Infrared Pyrometers

PRESSURE, STRAIN AND FORCE



Transducers & Strain Gages



Load Cells & Pressure Gages



Displacement Transducers



Instrumentation & Accessories

FLOW/LEVEL



Rotameters, Gas Mass Flowmeters & Flow Computers



Air Velocity Indicators



Turbine/Paddlewheel Systems



Totalizers & Batch Controllers

pH/CONDUCTIVITY



pH Electrodes, Testers & Accessories



Benchtop/Laboratory Meters



Controllers, Calibrators, Simulators & Pumps



Industrial pH & Conductivity Equipment

DATA ACQUISITION



Data Acquisition & Engineering Software



Communications-Based Acquisition Systems



Plug-in Cards for Apple, IBM & Compatibles



Datalogging Systems



Recorders, Printers & Plotters

HEATERS



Heating Cable



Cartridge & Strip Heaters



Immersion & Band Heaters



Flexible Heaters



Laboratory Heaters

ENVIRONMENTAL
MONITORING AND CONTROL



Metering & Control Instrumentation



Refractometers



Pumps & Tubing



Air, Soil & Water Monitors



Industrial Water & Wastewater Treatment



pH, Conductivity & Dissolved Oxygen Instruments

6-2720.090-OM/(B-11/01) M-2035/1101