Myron L ARH1 - Manual (Page 5)

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.
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.
• Pressing either measurement key starts a 20 second timer.
• Note the value displayed. It’s that simple!
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.
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
of displays conductivity or Total Dissolved Solids (TDS) with units
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. 2
3 ). 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.
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).
B. Maintenance of the pH Sensor
The sensor well must be kept wet with a solution. Before replacing the
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. 1
8 ) or at least a strong table salt solution.
Not distilled water (ref. pH, pg. 15).
IV. THE SPECIFIC RECOMMENDED MEASURING
P R O C E D U R E S
If the proper solution is not selected (KCl, NaCl or 442), see Solution
Selection, Pg. 8.
6 7
pH
COND
TDS