Myron L 762 User Manual

RESISTIVITY

MONITOR/CONTROLLERS

Installation • Operation • Maintenance

User Manual for Models: 750, 752, 753, 762

2450 Impala Drive

Carlsbad, CA 92010-7226 USA

Tel: [phone]
Fax: [phone]
www.myronl.com

Water Quality Instrumentation

Accuracy • Reliability • Simplicity

TABLE OF CONTENTS

SECTION PAGE
1 INTRODUCTION

1.1 SCOPE ........................................................................................................................................1

1.1.1 FUNCTIONAL DESCRIPTIONS .....................................................................................1

1.1.2 MONITOR APPLICATIONS ............................................................................................ 1

1.2 MONITOR SPECIFICATIONS .....................................................................................................1

1.3 RESISTIVITY CELLS ...................................................................................................................2

1.3.1 CELL PRODUCT SPECIFICATIONS ..............................................................................2

1.4 OPTIONAL INTERFACE FEATURES ..........................................................................................2

1.5 HOW TO ORDER ........................................................................................................................ 2

2 INSTALLATION

2.1 GENERAL ....................................................................................................................................3

2.2 MECHANICAL INSTALLATION ...................................................................................................3

2.2.1 SURFACE INSTALLATION .............................................................................................4

2.2.2 PANEL MOUNTING ........................................................................................................4

2.2.3 CELL INSTALLATION .....................................................................................................4

2.3 ELECTRICAL INSTALLATION .....................................................................................................4

2.3.1 MAIN AC POWER INSTALLATION................................................................................. 4

2.3.2 CELL INSTALLATION .....................................................................................................5

2.3.3 ALARM RELAY INSTALLATION ..................................................................................... 5

2.4 OPTIONAL INTERFACE CONNECTIONS ..................................................................................5

2.4.1 220 VAC CONVERSION.................................................................................................5

2.4.2 0-5/0-10 VDC RECORDER BOARD............................................................................... 6

2.4.3 4-20 mA AND 4-20D TRANSMITTER BOARDS .............................................................6

3 OPERATING PROCEDURES

3.1 GENERAL ....................................................................................................................................7

3.2 SWITCH AND INDICATORS CONTROLS .................................................................................. 7

3.2.1 MODEL 750 ....................................................................................................................7

3.2.2 MODEL 752 AND 753 .....................................................................................................7

3.2.3 MODEL 762 ....................................................................................................................7

3.3 OPERATIONAL CHECKOUT PROCEDURES ............................................................................8

3.3.1 MODEL 750 ....................................................................................................................8

3.3.2 MODEL 752, 753 AND 762 .............................................................................................8

4 COMPONENT IDENTIFICATION, CALIBRATION AND PREVENTIVE MAINTENANCE

4.1 GENERAL ....................................................................................................................................9

4.2 PRIMARY COMPONENT IDENTIFICATION ...............................................................................9

4.3 CALIBRATION PROCEDURES .................................................................................................10

4.3.1 METER MECHANICAL ZERO READING.....................................................................10

4.3.2 FULL SCALE CALIBRATION PROCEDURES .............................................................10

4.3.2.1 MODEL 750 .................................................................................................. 10

4.3.2.2 MODELS 752, 753 AND 762 ........................................................................ 10

4.3.3 INTERNAL SET POINT ADJUSTMENT .................................................................... 11

4.3.4 0-5/0-10 VDC RECORDER BOARD ......................................................................... 11

4.3.5 MODEL 753 WITH 4-20mA or 4-20D OPTION ..........................................................11

4.4 PREVENTIVE CARE ................................................................................................................. 12

5 APPENDIX

A REPLACEABLE COMPONENTS CHART .................................................................................13

SECTION 1

Introduction

1.1 SCOPE

This manual provides the necessary information to install,
operate and maintain the Myron L Company’s 750/760 Series
Resistivity Monitors. Sections 1 thru 3 provide the user with a
Monitor’s applicational description, mounting, wiring and
operational procedures. Section 4 identifies their primary
components and provides the user with easy-to-use calibration,
and preventive maintenance procedures.

Section 5 (Appendix) provides Replaceable Components
Charts.

1.1.1 FUNCTIONAL DESCRIPTIONS

All models have drip/weather-proof housing which can be panel
or surface mounted. The 750 models are a compact 6.0" x 5.0"
(152mm x 122mm). The 762 is 6.0" x 10.8" (1 52mm x 275mm).
All model front panels are equipped with bright green and red
LEDs that indicate “Above” or “Below” set point readings. Also
standard on all models is a heavy-duty 10 amp Alarm relay,
activating on decreasing readings.

For specific Monitor configurations, reference the following
individual model descriptions:

Model 750

Provides a front panel accessible set point adjustment knob in
place of an analog or digital meter readout display.

Model 752

Set point is internal to discourage unauthorized adjustments.
Standard front panel is equipped with a linear analog meter
display and a “SET POINT CHECK” switch.

1.2 MONITOR SPECIFICATIONS

RANGES:

0-20 megohm-cm
0-2 megohm-cm
0-200 kilohm-cm
0-500 kilohm-cm (Model 750 only)
0-20, 0-2, 0-0.20 megohm-cm, (Model 762 only)

READOUT:

Model 752: 2
Model 753: 1/2" x 3 1/2 Digit (13mm) Digital
Model 762: 4

ACCURACY:

Model 753: ±1 % of span
Other Models: ±2% of span

SENSITIVITY:

0.5% of span

STABILITY:

0.05% of span

REPEATABILITY:

0.1% of span

CELL INPUTS:

1 Input (standard)
3 Cell input (optional 762 only)

1

/2" (63mm) Analog

1

/2" (114mm) Analog

Model 753

Set point is internal to discourage unauthorized adjustments.
Standard front panel is equipped with a digital LCD meter
display and a “SET POINT CHECK” switch.

Model 762

Set point is internal to discourage unauthorized adjustments.
Standard front panel is equipped with a three (3) Range select
switch (0-20, 0-2, 0-0.2 megohm), a linear analog meter display
and a “SET POINT CHECK” switch.

1.1.2 MONITOR APPLICATIONS

1 Deionized (Dl) and distillation ultra-pure treatment

systems
2 Electronics
3 Food Processing
4 Plating
5 Power Plants
6 Laboratories

Introduction

RELAY FUNCTION:

Single set point control:

Continuously adjustable 0-100% of span

Indicators:

“ABOVE” (green) and “BELOW” (red) set point LEDs

Contact Rating:

SPDT 10 amp @ 250 VAC, 30 VDC. Relay activates on
decreasing readings

POWER SPECIFICATIONS:

115 VAC, 50/60 Hz ± 15%, 25mA
220 VAC, 50/60 Hz ± 15% (Optional)

AMBIENT TEMPERATURE RANGE:

-22°F ( -30°C) to 140°F (60°C)

CONSTRUCTION:

Fully gasketed heavy-duty ABS for corrosion resistance,
NEMA type 3 rated

WEIGHT:

(750 Series) 2 Ibs (0.9 kg)
(762) 3 Ibs (1.4 kg)

1

1.3 RESISTIVITY CELLS

All 750/760 Series Monitors use a CS10 Cell. These reliable
sensors feature two integral thermistors to ensure accurate and
rapid automatic temperature compensation. The sturdy
polypropylene bushing is modular for easy, inexpensive
replacement. Several alternatives for the metal portion of the cell
are available, depending on the demands of the application.

1.3.1 CELL PRODUCT SPECIFICATIONS

CONSTANT:

0.05

TEMPERATURE COMPENSATION:

Two integral thermistors provide automatic TC to 25°C
between 32-212°F (0-100°C)

PRESSURE/TEMPERATURE LIMITS:

100 psi (689.6 kPa) ~ 212°F (100°C)

BUSHING:

Modular Polypropylene threaded .75" NPT

CABLE:

Shielded Belden 8724; 10' (3 meters) standard,
Prespecified lengths of 25' (7.5 meters) or 100' (30 meters)
also available.

DIMENSIONS:

Metal portion 1.2" (95 mm) L; 0.5" (13 mm) DIA

1.4 OPTIONAL INTERFACE FEATURES

1 0-5/0-10 VDC Recorder Interface

2 4-20 mA Loop Powered Isolated Output (753 only)

1.5 HOW TO ORDER

EXAMPLE:

MODEL TYPES:

750: Small Controller with front panel “Set Point” adjustment

knob.

1

752: Small Monitor with 2

/2" analog meter display.
753: Small Monitor with 1/2" LCD digital meter display.
762: Large Monitor with 4 1/2" analog meter display and three

(3) range select switch.

RANGE SCALES:

1: 0-20 megohm-cm

2: 0-2 megohm-cm

3: 0-200 kilohm-cm

4: 0-20, 0-2, 0-0.20 megohm-cm (Model 762 only)

5: 0-500 kilohm-cm (Model 750 only)

3 4-20mA Self Powered Isolated Output (753 Only)

4 Three (3) Cell Input (762 only)

2

OPTIONS:

03: 3 Cell Input (Available on the 762 Monitor only)

510: 0-5/0-10 VDC Recorder Interface (Available on

all Models)

420: 4-20 mA Loop Powered Isolated Output

(Available on the 753 Monitor only)

420D: 4-20 mA Self Powered Isolated Output

(Available on the 753 Monitor only)

HOW TO ORDER CS10 CELL(S):

CS10-S 316 Stainless Steel

-T Titanium

Introduction

SECTION 2

Installation

2.1 GENERAL

This section contains the recommended procedures required to
properly install the 750/760 Series Monitors, to connect the
Cell(s), Alarm relay, Recorder and/or Transmitter cable
connections.

WARNING!

The Myron L Company recommends that all mounting and
electrical installation procedures be performed by trained and
authorized personnel ONLY! Failure to do so could result in
damage to equipment and/or property.

2.2 MECHANICAL INSTALLATION

All Monitor electronics are packaged inside drip/weatherproof
housings. Their physical dimensions have been designed to
allow for both surface and panel mounting.

There are three basic guidelines to consider when selecting the
monitor’s mounting location.

1 Select a site that limits the Monitor’s exposure to

excessive moisture and corrosive fumes.

2 For best results, position your control area as close as

possible to the point(s) being monitored.

Installation

3