Myron L ARH1 User Manual
TechPro
™
Operation
Manual
Model ARH1
MYRON L
COMPANY
10-02 (WEB) EG
Instrument Illustration
METER
pH/CONDUCTIVITY
Reference
Junction
(under Glass
Bulb)
pH Sensor
(User replaceable)
Conductivity Cell
(Built-in
Electrodes)
Temperature
Sensor
User selectable
temperature
compensation
ratios (Solution
Selection)
Icon for pH
LO BATT
KCl
NaCl
442
COND
TDS
pH/CONDUCTIVITY
mS
µS
PPM
PPT
°C
pH
TDSCOND
pH
pH Glass
Electrode
pH Sensor
Protective Cap
Units of Measurement
mS - millisiemens/cm
(millimhos/cm)
µS - microsiemens/cm
(micromhos/cm)
PPM - parts per million
PPT - parts per thousand
Icons for either
Conductivity or
Total Dissolved
Solids (TDS)
pH key
Conductivity or TDS key:
User selectable for either
Conductivity or TDS
(Switch Selectable)
Parameter
Conductivity
Conductivity
TDS
TDS
ARH1
MYRON L
COMPANY
For detailed explanations, see Table of Contents
Wrist/neck strap slot
(user supplied)
1-12-99
1
FEATURES and SPECIFICATIONS
A. Features
• Superior resolution 3 1/2 digit LCD
• Conductivity/TDS accuracy of ±1% of full scale
• pH accuracy of ± .05 pH units
• All electrodes are internal for maximum protection
• Latest electrode cell technology
• Water resistant
• Autoranging Conductivity/TDS
• Easy Conductivity/TDS and pH calibration
• User selectable Conductivity/TDS modes
• 3 “User Selectable” solution conversions (tempcos)
• Temperature Accuracy of ±1° C/F
B. General Specifications
Display 3 1/2 Digit LCD
Dimensions (LxWxH) 7.7x2.7x2.5 in.
196x68x64 mm
Weight 11.2oz./320g
Case Material ABS
Cond/TDS Cell Material ABS
Cond/TDS Cell Capacity 0.2 oz./5 ml
pH Sensor Well Capacity 0.04 oz./1.2 ml
Power 9V Alkaline Battery
Battery Life >100 Hours/5000 Readings
Operating/Storage Temperature 32-132°F/0-55°C
Protection Ratings IP64/NEMA 3
C. Specification Chart
D. Warranty/Service
The ARH1 has a 2 year warranty, excluding the pH sensor, which has
limited 6 month warranty. If an instrument fails to operate properly, see the
Troubleshooting Chart, pg. 17. The battery and pH sensor are user-replaceable
For other service, return the instrument prepaid to the Myron L Company.
MYRON L COMPANY
2450 Impala Drive
Carlsbad, CA 92010
USA
760-438-2021
If, in the opinion of the factory, failure was due to materials or
workmanship, repair or replacement will be made without charge. A
reasonable service charge will be made for diagnosis or repairs due to
normal wear, abuse or tampering. This warranty is limited to the repair or
replacement of the ARH1 only. The Myron L Company assumes no other
responsibility or liability.
E. TechPro™ Series Models
TechPro Series Models pH1 AR1 ARH1
Parameters pH Conductivity or TDS, Conductivity or TDS,
& Temperature & Temperature pH & Temperature
Additional information available on our web site at:
www.myronl.com
ARH1 p H Conductivity TDS Temperature
Ranges 0-14 pH 0-1999 µS 0-1999 ppm 0-71° C
2-19.90 mS 2-19.90 ppt 32 - 16 0° F
in 3 autoranges in 3 autoranges
Resolution .01 pH 0.1 (<200 µS) 0.1 (<200 ppm) 0.1° C/F
1 (<2000 µS) 1 (<2000 ppm)
0.01 (>2 mS) 0.01 (>2 ppt)
Accuracy ±.05 pH ±1% of Full Scale ±1.0° C/F
Auto Temperature 0-71° C 0-71° C
Compensation 32 - 160° F 32 - 160° F
Conductivity or KCl, NaCl or 442™
TDS Ratios
2 3
TABLE OF CONTENTS
Instrument Illustration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
FEATURES and SPECIFICATIONS. . . . . . . . . . . . . . . . . . . . . . . . . 2
A. Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
B. General Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . 2
C. Specification Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
D. Warranty/Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
E. TechPro Series Models . . . . . . . . . . . . . . . . . . . . . . . . .3
I. INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
II . RULES of OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
A. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
B. Characteristics of the Keys . . . . . . . . . . . . . . . . . . . . . . 6
C. Operation of the Keys . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1. Measurement Keys in General . . . . . . . . . . . . 6
2. COND/TDS Key. . . . . . . . . . . . . . . . . . . . . . . . .7
3. pH Key . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
III. AFTER USING the ARH1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
A. Maintenance of the Conductivity Cell . . . . . . . . . . . . . 7
B. Maintenance of the pH Sensor. . . . . . . . . . . . . . . . . . . 7
IV. THE SPECIFIC RECOMMENDED MEASURING
PROCEDURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
A. Measuring Conductivity/Total Dissolved Solids . . . . .8
B. Measuring pH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
VII. CALIBRATION INTERVALS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
A. Suggested Intervals . . . . . . . . . . . . . . . . . . . . . . . . . . .13
B. Calibration Tracking Records . . . . . . . . . . . . . . . . . . . 13
C. Conductivity or TDS Practices . . . . . . . . . . . . . . . . . . 13
D. pH Practices. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
VIII. CHANGING from CENTIGRADE to FAHRENHEIT. . . . . . . . . . . . 14
IX. CARE and MAINTENANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
A. Temperature Extremes . . . . . . . . . . . . . . . . . . . . . . . . 14
B. Battery Replacement (LO BATT) . . . . . . . . . . . . . . . . 14
C. pH Sensor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
D. Cleaning Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
X. TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
XI. ACCESSORIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
A. Conductivity/TDS Standard Solutions . . . . . . . . . . . 18
B. pH Buffer Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
C. pH Sensor Storage Solution . . . . . . . . . . . . . . . . . . . .18
D. Soft Protective Case . . . . . . . . . . . . . . . . . . . . . . . . . . 18
E. Replacement pH Sensor. . . . . . . . . . . . . . . . . . . . . . . 19
XII. TEMPERATURE COMPENSATION . . . . . . . . . . . . . . . . . . . . . . . 19
A. Standardized to 25°C . . . . . . . . . . . . . . . . . . . . . . . . . .19
B. Tempco Variation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
C. An Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
D. A Chart of Comparative Error . . . . . . . . . . . . . . . . . . . .20
E. Other Solutions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
V. SOLUTION SELECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
A. Why Solution Selection is Available . . . . . . . . . . . . . . .8
B. The 3 Solution Types . . . . . . . . . . . . . . . . . . . . . . . . . . .8
C. Procedure to Select a Solution . . . . . . . . . . . . . . . . . . 9
D. Procedure to Select the Units of Measurement . . . . .9
VI. CALIBRATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
A. Calibration Intervals . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
B. Rules for Calibration of the ARH1 . . . . . . . . . . . . . . . .10
1. Calibration Steps . . . . . . . . . . . . . . . . . . . . . . .10
2. Calibration Limits . . . . . . . . . . . . . . . . . . . . . . .10
C. Calibration Procedures. . . . . . . . . . . . . . . . . . . . . . . . .10
1. Conductivity or TDS Calibration. . . . . . . . . . .10
2. pH Calibration . . . . . . . . . . . . . . . . . . . . . . . . . 11
4 5
XIII. CONDUCTIVITY CONVERSION to TOTAL DISSOLVED SOLIDS
(TDS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
A. How it’s Done . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
B. Solution Characteristics . . . . . . . . . . . . . . . . . . . . . . . .21
C. When does it make a lot of difference? . . . . . . . . . . . 22
XIV. TEMPERATURE COMPENSATION (Tempco)
and TDS DERIVATION. . . . . . . . . . . . . . . . . . . . . . . . . . . .22
XV. pH MEASURING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
XVI. GLOSSARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
NOTES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . 27
I. INTRODUCTION
Thank you for selecting the TechPro™ Series, Model ARH1, one of the
Myron L Company’s latest in a new line of digital instruments utilizing
advanced circuitry. This circuitry makes it very accurate and easy to use
(see pages 2 & 3 for Features and Specifications on this and other
models). For your convenience, on the bottom side of your ARH1 is a
brief set of instructions.
Special note ...... Conductivity/TDS require mathematical correction to
25°C values (ref. Temperature Compensation, pg. 19).
On the left side of the ARH1 liquid crystal display is shown an indicator of
the salt solution characteristic used to model temperature compensation
(Tempco) of conductivity or its TDS conversion. The indicator can be KCl,
NaCl or 442. Internal selection affects the temperature correction of
conductivity, and the calculation of TDS from compensated conductivity
(ref. Conductivity Conversion to TDS, pg. 21).
The selection can affect the reported conductivity of hot or cold
solutions, and will change the reported TDS of a solution. Generally,
using KCl for conductivity and 442™ (Natural Water characteristic) for TDS
will reflect present industry practice for standardization. NaCl may also be
selected for either conductivity or TDS as is needed.
Your instrument, as shipped from the factory, is set for conductivity with
the KCl tempco. However, if you are measuring natural waters and wish to
have maximum accuracy, you may want to change it to the 442 tempco
setting. To change the Tempco or to read in TDS/ppm, see Solution
Selection on pg. 8.
The mode is shown at the bottom of the display, and the measurement
units appear at the right.
2. COND/TDS Key
This key is used with solution in the Conductivity Cell.
Precautions:
• While filling cell cup ensure no air bubbles cling on the cell wall.
• If the proper solution is not selected (KCl, NaCl or 442), refer to
Solution Selection on pg. 8.
Solution to be tested is introduced into the conductivity cell and a press
COND
of displays conductivity or Total Dissolved Solids (TDS) with units
TDS
on the right. On the left is shown the solution type selected for
conductivity. An overrange condition will show only [- - - -].
3. pH Key
Measurements are made on the solution held in the pH sensor well (ref.
pH Measuring, pg. 23). The protective cap is removed, and the sensor
well is filled and rinsed with sample enough times to completely replace
the storage solution. After use, the pH sensor well must be refilled with
Myron L Storage Solution, and the protective cap reinstalled securely
(ref. Maintenance of the pH Sensor, below, and pH, pg. 15).
A press of displays pH readings. No units are displayed.
pH
II. RULES of OPERATION
A. Operation
Using the instrument is simple:
• Individual or dual parameter readings may be obtained by filling
individual sensors or entire cell cup area.
• Rinse the Conductivity cell or pH sensor well with test solution 3
times and Refill.
III. AFTER USING the ARH1
A. Maintenance of the Conductivity Cell
Rinse out the cell cup with clean water. Do not scrub the cell. For oily
films, squirt in a foaming non-abrasive cleaner and rinse. Even if a very
active chemical discolors the electrodes, this does not affect the
accuracy; leave it alone (ref. Conductivity or TDS, pg. 15).
• Pressing either measurement key starts a 20 second timer.
• Note the value displayed. It’s that simple!
B. Maintenance of the pH Sensor
The sensor well must be kept wet with a solution. Before replacing the
B. Characteristics of the Keys
• Your ARH1 is designed to provide quick, easy, accurate
measurements by simply pressing one key.
• Both functions are performed one key at a time.
C. Operation of the Keys (See Instrument Illustration on page 1)
1. Measurement Keys in General
The measurement keys turn on the instrument in the mode selected.
rubber cap, rinse and fill the sensor well with (in order of preference):
Myron L Storage Solution, an almost saturated KCl solution, pH 4 buffer
(ref. pH Buffer Solutions, pg. 18) or at least a strong table salt solution.
Not distilled water (ref. pH, pg. 15).
IV. THE SPECIFIC RECOMMENDED MEASURING
PROCEDURES
If the proper solution is not selected (KCl, NaCl or 442), see Solution
Selection, Pg. 8.
6 7
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