Myron L M6/PH - Manual (Page 4)

pH CALIBRATION/MAINTENANCE
pH STANDARD BUFFER SOLUTIONS
All pH sensors "drift" and decrease in strength as they age. pH
meters have two Calibration Controls to compensate for those effects.
ZERO adjust corrects for "drift" of the pH sensor's response to neutral
pH solutions. GAIN adjust amplifies the signal from the pH sensor
for accurate readings of other pH values.
Use pH standard buffer solutions to calibrate all pDS meters. The
recommended values are 4, 7, and 10. For greatest accuracy, adjust
with the buffer closest in pH to the samples to be tested.
pH ZERO ADJUST (Frequency: weekly)
Test by rinsing and refilling the cell with 7 buffer and pressing the
red button. The meter should indicate 7 on the red scale. If it is
necessary to calibrate Zero, perform the following steps:
1. Remove the bottom cover using fingernails or a small screwdriver
to loosen the front or rear edge.
2. Refill cell with 7 buffer (see pH MEASUREMENT for proper
procedure).
3. Press the red button and turn the pH Zero control untiI the needle
indicates 7.
4. Recap the pH compartment and replace the bottom cover.
pH GAIN (SLOPE) ADJUST (Frequency: bi-monthly)
The Gain should be calibrated approximately once every eight
weeks. The Gain Control is used with 4 and 10 buffers.
NOTE: Never adjust the Gain control without first adjusting Zero.
Test by rinsing and refilling the cell with 4 or 10 buffer and pressing
the red button. The meter should indicate the buffer value on the red
scale. If it is necessary to calibrate the Gain perform the following
steps:
1. Remove the bottom cover.
2. Rinse and fill the
pH compartment with 4 buffer and press the red
button. Adjust the Gain control until the needle indicates 4.
3. Rinse three times and test with 10 buffer. If adjustment is
necessary, adjust to only half way between the initial reading
and 10. If, after this, the 4 and 10 buffer readings are not less
than one division from 4 and 10, the sensor is deteriorating and
should be replaced. The sensor should also be replaced if the
Gain control c
an not make the pointer reach either 4 or 10.
MAINTENANCE
BATTERY CHECK
Models EP11/pH and M6/pH have a battery indicator glow light
visible through the small hole on the lower right-hand corner of the
meter face plate. If this light fails to glow when the black button is
pressed, replace both batteries.
BATTERY REPLACEMENT
To replace the batteries detach the battery connectors. Pull on the
plastic straps to remove the batteries. Replace with fresh zinc carbon
or alkaline 9 volt batteries. Reinsert the plastic straps to secure
batteries.
CELL CUP
Self-conditioning of the built-in electrodes occurs each time the
button is pressed with a sample in the cell cup. This ensures
consistent results each time. With some samples a small downward
swing of the pointer is a result of this conditioning action. This action
is powerful and removes normal films of oil and dirt. However, if very
dirty samples - particularly scaling types - are allowed to dry in the
celI cup, a film will build up. This film reduces accuracy. When there
are visible films of oil, dirt, or scale in the cell cup or on the electrodes,
scrub them lightly with a small brush and household cleanser. Rinse
out the cleanser, and the meter is ready for accurate measurements.
pH SENSOR
The unique pH electrode in your pDS meter is a nonrefillable
combination type which features a porous Teflon* liquid junction
(covered by U.S. Patent No. 4128468). It should never be allowed
to dry out (see pH MEASUREMENT). If it does, the sensor can
sometimes be renewed by soaking in a saturated potassium chloride
(KCI) solution for several days.
"Drifting" can be caused by a film on the sensor bulb. Use a liquid
cleaner such as Windex ™ or Fantastic ™ to clean it. The sensor buIb
is very thin and delicate. Excessive pressure during cleaning may
break it.
Leaving high pH (alkaline) solutions in contact with the pH sensor
for long periods of time can damage it. Rinsing such liquids from the
pH compartment and moistening it with 4 buffer or tap water will
extend its useful life.
Samples containing chlorine, sulphur, or ammonia can "poison"
any pH electrode. If it is necessary to measure the pH of any such
sample, thoroughly rinse the pH sensor with clean water immediately
after taking the measurement. Any sample element which will reduce
(add an electron to) silver, such as cyanide, will attack the reference
electrode.
Replacement sensors are available only from the Myron L
Company or our authorized distributors (see ACCESSORIES).
*™ DuPont Company
WATER INSIDE THE METER
Your Myron L meter is a rugged instrument and will withstand water
exposure around its cell, meter movement, and switches. However,
care should be taken to keep water from leaking in around the bottom
cover. It is not sealed (to prevent condensation from forming).
If the water is relatively clean (i.e., tap water or better), and there
are only a few drops inside the meter, dry it as described below.
Large amounts of water, or corrosive or very dirty solutions will almost
certainly damage the meter movement or electronics. Such meters
should be returned to the Myron L Company for repair.
To dry your meter:
1. Shake excess water out of the inside of the meter.
2. Dab the exposed surface dry with an absorbent cloth or tissue.
Avoid pushing any water into the Calibration Controls or the
switches.
3. Air dry the meter in a warm area with the bottom cover off. Allow
several hours for thorough drying.
If the water entered through a leak in the case or cell, or if the
instrument shows erratic readings or other unusual behavior, return
it to the Myron L Company for servicing.