This manual serves to explain the use of the pH 5 PLUS meter.
This manual functions in two ways: Þ rst as a step by step guide to
operating the meter; second, as a handy reference guide.
This manual is written to cover as many anticipated applications of
the meter as possible. If there are questions about the use of this meter
contact the LaMotte Tech Service Department.
LaMotte Company will not accept any responsibility for damage or
malfunction to the meter caused by improper use of the instrument.
The information presented in this manual is subject to change without
notice as improvements are made, and does not represent a commitment
on the part of LaMotte Company.
*WARNING: Reagents marked with an * are considered to be potential
health hazards. To view or print a Safety Data Sheet (SDS) for these
reagents go to www.lamotte.com. Search for the four digit reagent code
number listed on the reagent label, in the contents list or in the test
procedures. Omit any letter that follows or precedes the four digit code
number.
.
WARNING! This set contains chemicals that
may be harmful if misused. Read cautions on
individual containers carefully. Not to be used by
The pH 5 PLUS microprocessor-based handheld meter is economical and
easy to use. It has a large custom LCD (Liquid Crystal Display) for clear
and easy reading. The pH 5 PLUS measures pH and temperature (°C).
Meters include 4 alkaline AAA batteries, a rubber boot /stand,
instruction manual, and warranty card. Please refer to Section 8
Replacement Parts and Accessories for information on additional
accessories and calibration solutions.
2. GETTING STARTED
2.1 Description of Keypad Functions
The pH 5 PLUS has four keys on the splash-proof keypad: ON/OFF,
HOLD/ENTER, CAL and MODE/INC.
ON/OFF
MODE/INC
CAL
HOLD
ENTER
Powers meter on and o . Meter starts up in the mode that
was last used.
Increments values during temperature calibration mode.
Allows calibration for pH or Temperature, or to abort
calibration and return to measure without conÞ rming a
value.
The large custom LCD consists of 3½-digit segments which uses
annunciators for pH or °C (Temperature). Other annunciators include
HO (when HOLD function is activated) and LO (low battery
condition).
2.3 Inserting & Removing the Rubber Boot/Stand
1. To remove the meter from the rubber boot, push out the bottom
edge of the meter until it is completely out of the boot. Ensure
that the probe cables are not connected. See Figure 1.
2. To insert the meter into the rubber boot, slide in the top of the
meter before pushing the bottom edge of the meter down to set it
into position. Lift up the stand at the back of the meter for bench
top applications. Figure 2.
The battery compartment is found at the back of the instrument. To open
the battery compartment, push the cover in the direction of the arrow
and lift up. Note the polarity of the batteries before inserting them into
position. After the batteries have been replaced, reposition the cover and
press down until it locks.
2.5 Battery Replacement
The LO annunciator on the LCD alerts when battery power is
running low.
Caution: Power o the meter before changing battery.
2.6 Connecting the Electrode and Temperature Sensor
To connect the probe to the meter, align the BNC connector slots with
the posts of the meter socket and rotate the connector clockwise until
it locks. Do not force the connector. To remove the probe, rotate the
connector in a counter-clockwise direction until it unlocks, and slide the
connector o the socket.
BNC connector
pH probe
2.5 mm mini phono
jack for
temperature sensor
Insert the mini phono jack of the temperature sensor into the socket on
the meter. Unplug the phono jack when not in use or when measuring pH
without temperature compensation.
2.7 Conditioning the pH Electrode
For best results condition the pH probe before the Þ rst use, or if it has
not been used for a long time, by soaking it in pH 4 bu er solution for at
least 1 hour. Rinse before use.
1. Press the ON/OFF key. All LCD segments will display
momentarily as the meter performs a self-diagnostic test. The
meter will display - - - if the meter has not been calibrated or if
the meter has been reset.
2. Press the MODE key to choose the desired measurement mode.
3. If a temperature probe is not connected, either 25.0°C (factory
default) or the last calibrated temperature value will be
displayed. If a temperature probe is connected, the current
measured temperature will be displayed.
4. Or (Over range) indicates the reading exceeds the maximum
measurement range.
Ur (Under range) indicates the reading is under the minimum
measurement range (see Section 7 SpeciÞ cations).
3. CALIBRATION
3.1 pH Calibration
The meter is capable of calibrating up to 3 pH values using USA or NIST
(nSt) pH bu er standards or 2 pH values with Low Ionic (Pb) pH bu er
standard. All new calibration values will automatically override existing
data.
USA group4.01, 7.00, 10.01
NIST group4.01, 6.86, 9.18
Pb group4.10, 6.97
For the best results perform at least a 2-point calibration at room
temperature (25 °C) using standard bu ers. Begin with pH 7.00 (USA
group), pH 6.86 (NIST group) or pH 6.97 (Pb group).
For a 1-point calibration, the calibration should be performed with a pH
bu er value closest to the expected sample value being measured.
The meter has automatic bu er recognition that identiÞ es the correct pH
bu er values during the calibration. The meter will accept calibration
values that are within ±1.0 pH units of the expected value, otherwise
the DISPLAY will ß ash Er1 and the value will not be accepted. Press
CAL to abort the calibration and return to the measurement mode.
Always use new pH bu er solutions for calibration. Do not reuse
bu er solutions that may be contaminated and a ect the calibration
and accuracy of the measurements. Promptly seal containers and store
solutions in a dark, dry, cool environment.
Before use, remove the plastic protective cap on the pH probe and
condition the glass bulb by soaking it in tap water or pH bu er
(preferably pH 4) for 1-2 hours. This will hydrate the glass bulb if the
probe is too dry or if it has not been used recently. Always rinse the
probe with clean water before and after each calibration or sample
measurement to avoid cross-contamination. For details refer to Section 5
on Probe Care and Maintenance.
3.1.1 pH Calibration Procedure Single Point
1. Pour a known pH bu er calibration standard solution, e.g. pH
7.00, into a clean, dry container. Turn on the meter and select the
pH mode by pressing the MODE key.
2. Dip the pH probe and temperature probe into the solution. Stir
gently and wait for the reading to stabilize (approximately 30
seconds depending on the probe condition).
3. Press CAL to enter the pH calibration mode. CA will be
displayed momentarily before the display will ß ash the current
un-calibrated reading.
To abort or cancel the calibration without accepting the new
value, press the CAL key. The meter will automatically revert to
the pH measurement mode.
4. Allow the reading to stabilize. Press the ENTER key to conÞ rm
the calibration. CO will be displayed momentarily.
5. Press the CAL key to return to the measurement mode.
1. Pour a 7.0 pH bu er calibration standard solution into a clean,
dry container. Turn on the meter and select the pH mode by
pressing the MODE key.
2. Dip the pH probe and temperature probe into the solution. Stir
gently and wait for the reading to stabilize (approximately 30
seconds depending on the probe condition).
3. Press CAL to enter the pH calibration mode. CA will be
displayed momentarily before the display will ß ash the current
un-calibrated reading.
To abort or cancel the calibration without accepting the new
value, press the CAL key. The meter will automatically revert to
the pH measurement mode.
4. Allow the reading to stabilize. Press the ENTER key to conÞ rm
the calibration. CO will be displayed momentarily.
5. Pour a known pH bu er calibration standard solution, e,g, pH
4.00, into a clean, dry container.
6. Dip the pH probe and temperature probe into the solution. Stir
gently and wait for the reading to stabilize (approximately 30
seconds depending on the probe condition).
7. Allow the reading to stabilize. Press the ENTER key to conÞ rm
the calibration. CO will be displayed momentarily.
8. Press the CAL key to return to the measurement mode.
3.1.3 Changing the pH Buffer Group
The meter can be calibrated with pH standards of USA, NIST (nSt) or
Low Ionic (Pb) pH bu er groups. The factory default is the USA bu er
group. To abort the bu er group selection, press CAL to revert to the pH
measurement mode.
1. Press and hold MODE while switching the meter on using the
ON/OFF key. The display will show bUF blinking.
2. Press the ENTER key to begin the bu er group selection mode.
Use the MODE key to toggle between USA, NIST or Pb as
shown below.
Press the ENTER key to conÞ rm the selection. The meter will
automatically revert to the pH measurement mode. The meter will save
the selected group indeÞ nitely until it is changed.
3.1.4 Resetting User Calibrated Values
The calibrated pH values can be reset to the factory default using the
procedure below. The temperature o set will not be reset using this
procedure. To abort the reset, press CAL to revert to the measurement
mode.
1. Press and hold CAL while switching the meter on using the ON/OFF key. The DISPLAY will show rSt blinking.
2. Press the ENTER key to conÞ rm. The meter will automatically
clear all stored pH calibrations and revert to the measurement
mode.
3.2 Temperature Calibration
3.2.1 With Temperature Probe
The temperature probe supplied with the meter is factory calibrated. Over
time, the temperature calibration may drift and require recalibration. If
the temperature probe is replaced the meter should be recalibrated.
1. Connect the temperature probe to the meter. Press the MODE
key until the °C annunciator appears on the DISPLAY.
2. Compare the displayed value to a NIST certiÞ ed thermometer or
other thermometer known to be accurate. For the most accurate
results, place both the probe and thermometer in a constant
temperature bath.
3. Press the CAL key to enter the temperature calibration mode.
The DISPLAY will show CA momentarily and the displayed
reading will ß ash.
4. Press INC key until the display shows the desired temperature.
The meter will allow an adjustable maximum value of ±5 °C
from the factory default.
5. To cancel or abort this operation, press the CAL key. To conÞ rm
the calibration, press the ENTER key. A new value will be
stored in the meter non-volatile memory. The meter will display
CO momentarily, and then revert to the measurement mode.
3.2.2 Without Temperature Probe (no ATC)
If a temperature probe is not used, the meter will compensate the pH
response based on a temperature value that has been manually set or at
the factory default of 25.0 °C.
1. Press the MODE key until °C shows on the DISPLAY.
2. Compare the displayed value to a NIST certiÞ ed thermometer or
thermometer that is known to be accurate (dipped into a constant
temperature bath).
3. Press the CAL key to enter the temperature calibration mode.
The DISPLAY will show CA momentarily and the displayed
reading will ß ash. Note that the displayed value should be either
4. Press the INC key until the displays shows the desired
temperature. The value can be set from 0 to 100 °C.
5. To cancel or abort this operation, press the CAL key. To conÞ rm
the calibration, press the ENTER key. A new value will be
stored in the meter non-volatile memory. The DISPLAY will
display CO momentarily, and the meter will revert to the
measurement mode.
4. MEASUREMENT
4.1 Taking Measurements
1. Before measurement, rinse the pH probe and temperature probe
with clean water to remove any impurities.
2. Power on the meter using the ON/OFF key. Press the MODE
key to select the desired mode of operation (pH or Temperature).
3. Dip the probes in the aqueous test sample. Stir gently with the
probes and wait for the reading to stabilize. Note the reading.
Freeze the displayed if desired for details refer to Section 4.2
Holding a Reading.
4. Rinse the probes with clean water before taking the next reading
or storing the meter.
4.2 Holding a Reading
To freeze or hold the displayed reading, press the HOLD key once. The
DISPLAY will display the HO annunciator to indicate the HOLD
function is activated.
Press the HOLD key once again to deactivate the HOLD function
or to release the frozen reading. The meter will revert to the current
measurement mode, and the HO annunciator will disappear from the
DISPLAY.
5. ELECTRODE CARE AND MAINTENANCE
For best results, store the pH probe bulb wet. Store the pH glass bulb
in pH probe storage solution. NEVER use deionized water for storage.
Wash probes with clean water after each use.
pH probes are susceptible to contamination and dirt. Clean them as
needed using mild detergent and warm water. Blot the probe gently with
soft tissue paper to dry. Avoid excessive rubbing of the glass membrane
and avoid touching it with the Þ ngers. Recalibrate after cleaning.
*WARNING: Reagents marked with an * are considered to be potential health hazards. To view
print a Safety Data Sheet (SDS) for these reagents Search for the four digit
reagent code number listed on the reagent label, in the contents list or in the test procedures. Omit
any letter that follows or precedes the four digit code number. For example, if the code is 4450WTH, search 4450. To obtain a printed copy
, contact LaMotte by email, phone or fax.
To order individual reagents or test kit components, use the speciÞ ed code number
.
or
9. WARRANTY
LaMotte Company warrants this instrument to be free of defects in parts
and workmanship for 3 years from the date of shipment and the probe
to be free of defects in parts and workmanship for 6 months from the
date of shipment. If it should become necessary to return the instrument
for service during or beyond the warranty period, contact our Technical
Service Department for a return
authorization number for troubleshooting
help. The sender is responsible for shipping charges, freight, insurance
and proper packaging to prevent damage in transit. This warranty
does not apply to defects resulting from action of the user such as
misuse, improper wiring, operation outside of speciÞ cation, improper
maintenance or repair, or unauthorized modiÞ cation. LaMotte Company
speciÞ cally disclaims any implied warranties or merchantability or Þ tness for a speciÞ c purpose and will not be liable for any direct,
indirect, incidental or consequential damages. LaMotte Company s total
liability is limited to repair or replacement of the product. The warranty
set forth above is inclusive and no other warranty, whether written or
oral, is expressed or implied.
Should it be necessary to return the meter for repair or servicing,
pack the meter carefully in a suitable container with adequate packing
material. A return authorization number must be obtained from LaMotte
. Often a problem can be
resolved over the phone or by email. If a return of the meter is necessary,
attach a letter with the return authorization number, meter serial number,
a brief description of problem and contact information including phone
and FAX numbers to the shipping carton. This information will enable
the service department to make the required