Extech Instruments ExStik FL700 User Manual

User Guide

ExStik® FL700

Fluoride Meter

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Introduction

The model FL700 is a system specifically designed for the quick and accurate measurement of
fluoride ions in drinking water and other aqueous samples. Unlike other electrode based systems
the FL700 consists of the sensing electrode, measuring electronics, and the display in one
convenient package. This meter is shipped fully tested; with proper use, this instrument will
provide years of reliable service.

Features

 Automatic temperature compensation (±10

o

C of calibration temperature)

 Automatic calibration

 Stability sensing to optimize accuracy

 Internal Datalogger for storing up to 25 readings

 Direct reading of ppm, mV, or mg/l units

 Automatic power off after 12 minutes to preserve battery life

 Internal error detection

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Description

Meter Description

1. Battery compartment cover

2. LCD Display

3. MODE/HOLD button

4. CAL/RECALL button

5. ON/OFF button

6. Electrode Retaining Collar (ring)

7. Electrode Sensor

(Note: The Electrode storage cap is not shown this diagram)

Electrode Sensor Description

The sensing electrode is a europium doped lanthanum fluoride single
crystal that has been incorporated into a removable sensing module that
houses a reference electrode and temperature measurement system. The
high resistance electrode signals are impedance converted to a low resistance output in the
sensing module to ensure stable and noise free performance.

Reagent Tablets

The FL700 allows the users to follow the ASTM and EPA standard methodology using any of the
TISAB reagents and standards already in use. Also, Extech has developed tablet-form TISAB
which contains all of the essential and approved chemicals that are found in the usual TISAB
reagents. A total ionic strength adjustment buffer (TISAB) is a buffer solution which increases
the ionic strength of a solution to a relatively high level.

The “dry” TISAB reagent does not contribute to sample dilution. The benefits of this method are:

1. No volumetric errors

2. Independent of sample size (± 20% of nominal sample volume)

3. Easy to use in the field or laboratory

4. Can be shipped more easily than liquid reagents

5. Lower cost per test

LCD Display

1. Bargraph display

2. Measurement units

3. Main display

4. Low (L) and High (H) Calibration icons

5. Data HOLD indicator

6. Low Battery indicator

7. Temperature display

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Operation

Preparation for use

1. Remove the FL700, electrode module and sample cup from its box. Remove caps from
module

2. If not already done, fit the electrode module onto the end of the meter body, making sure
that the slots line up correctly, and turn the module retaining ring to secure the assembly.

Powering the FL700

Press the ON/OFF button to turn the meter on or off. If the batteries are weak, the ‘BAT’
indicator appears on the LCD.

Power-On Diagnostics

1. When the meter is switched ON the LCD displays “SELF” and “CAL” while the meter runs a
diagnostic routine

2. During this time the meter is recalling the user calibration data, performing self diagnostics &
initializing the circuitry

3. When completed, the meter proceeds to the normal measurement mode

Calibration

The FL700 can be calibrated between 1.0 ppm and 10 ppm or between 0.5 and 5.0 ppm Fluoride
ion. Set the Mode to ppm. The following calibration procedure assumes the normal 1.0 to 10 ppm
range has been chosen.

1. Prepare a 1 ppm fluoride standard solution by placing one TISAB tablet into a sample cup
and add 20 mls of the 1ppm Fluoride standard into the sample cup.

Note: if your 1ppm Fluoride standard already contains TISAB do not use a TISAB tablet.

2. Create a rinse solution that can be used between sample measurements buy dissolving
1 TISAB tablet in 20ml of Distilled water. The rinse solution promotes faster response times.

3. Rinse the end of the FL700 module in this Rinse solution or in Distilled water and then wipe
thoroughly with a paper tissue.

4. Place the FL700 into the prepared 1 ppm standard and switch the instrument ON using the
ON/OFF button. The instrument will now go through its self-calibration.

5. The instrument will enter HOLD mode in about 35 seconds when stabilized in the 1.0 ppm
standard solution.

6. Press and HOLD the CAL key, CAL will appear in the display followed by 0.5ppm and

5.0ppm. Continue holding the CAL button until 1.0 ppm and CAL appear in the display.
Release the CAL key.

7. Wait until the display stops blinking; the instrument will enter the normal measurement
mode.

8. The instrument is now calibrated and ready for use.

9. The circled L and H icons on the display indicate that the low range (L) and high range (H)
calibrations have been completed.

Calibration frequency

Calibrate the FL700 prior to each new measurement batch or if more than 12 hours has elapsed
since the last calibration.