3
About Your eXact
®
Micro 7+ Instrument
In order to save power, the meter is designed to turn off after 3 minutes (timed from the last button pressed).
Should the meter turn off in the middle of a test, the last stored zero in the meter will remain valid when the
meter is turned on again. Also, the test result is stored in memory for easy retrieval.
The eXact
®
Micro 7+ meter is controlled by three buttons:
1.
ZERO/ON
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pressed, it zeroes the sample in the cell. Once the meter is zeroed, this zero value applies to all parameters
and is stored and retained even when meter turns off. However, it is recommended that each new water
sample analyzed is zeroed before testing, to maximize sensitivity and accuracy.
2.
MENU
: With each press, the MENU button advances through the tests in the following sequence: CL1,
PH2, BR3, AL4, CA5, CU6, TR7, HR8. Each test menu can store up to 20 results. To
retrieve the stored
results
, go to the desired test using the MENU key. When the desired test is displayed,
press and hold
down the MENU key
. Continue holding down the MENU key to scroll the stored results for that test, starting
with the most recent result. The meter will display, from memory, the last 20 readings in sequence beginning
with -20, which is the latest result, followed by -19, which is the 2
nd
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the oldest result retained. Only the last 20 readings are stored in each menu. This meter is able to store 160
results in memory (20 in each menu).
3.
READ
: When pressed once, this button starts the timer for the parameter being tested. When pressed a
second time the meter exits the timer and immediately prepares to colorimetrically measure the sample, and
simultaneously stores the measurement in memory.
If the parameter being measured is below or above the detection range, the display will show “
LO
” (Under
Range) or “
HI
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AWWA
4500-Cl G
eXact
®
DPD-1
Anhydrous DPD sulfate
Anhydrous Na
2
HPO
4
Anhydrous KH
2
PO
4
Na
2
EDTA
1.5%
33.4%
64.0%
1.1%
1.5%
33.4%
64.0%
1.1%
Component
(Free Chlorine)
About The Accuracy / Calibration Of The Micro 7+ System
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VSHFWURSKRWRPHWULFPHWKRGV7KHDOJRULWKPVLQWKHVRIWZDUHUHÀHFWWKHEHVWFRUUHODWLRQRIWKHH;DFW
®
Micro 7+ Systems against the AWWA, US EPA , DIN, and ISO reference test methods for chlorine.
Studies show that the eXact
®
Micro 7+ System repeatedly agrees with an EPA Compliant reference
method greater than 99% (R
2
= 0.9989, 0 - 6.0 ppm - see page 36). The eXact
®
Micro 7+ Advanced
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calibrations in the meter to be valid for the life of the meter because of the quality, Long-Life LED, the
photo cell, and the software as written into the meter. This is why the meter comes with a 2-Year
Warranty. NOTE: Test algorithms in the new version of photometer (serial numbers above 5000) give
accurate results in fresh and salt water.
Compliance VHULÀFDWLRQIRU)UHHDQG7RWDO&KORULQH7HVWLQJ
This DPD test system is accepted by most health departments because this test is USEPA (DIN
Standard 38 408 G4, ISO 7393/2) accepted for testing requirements for Free and Total Chlorine. The
Micro 7+ meter uses a wavelength of 525nm; and the compliance requirement is that the colorimeter
wavelength is between 490 and 530nm. The eXact
®
Strip Micro CL (DPD-1) uses the same reagents
and proportions, and the resulting solution pH is maintained between 6.2 and 6.5 as VSHFL¿HGby
AWWA (American Water Works Association) method 4500-Cl G. It should be understood that the
USEPA does not "approve" commercial DPD delivery systems such as reagent powder pillows, tablets,
dispensers, or eXact
®
Strip DPD delivery devices. The eXact
®
Strip Micro CL (DPD-1) for Free
Chlorine, and the eXact
®
Strip Micro CL (DPD-3) or the eXact
®
Strip Micro CL (DPD-4) for Total
Chlorine meet your reportable testing requirements because the eXact
®
Strip Micro CL delivers the
same chemicals in identical proportions (see table below); therefore, the system is compliant. Likewise,
AWWA proportions are followed as required for Total Chlorine measurements using Potassium Iodide.
