Metex 8760CLP Total Free Chlorine & pH Analyzer - Manual (Page 27)

AQUAMETRIX INC.
1-800-742-1413 www.aquametrix.com
27
Inserting Chlorine Sensor in the Flow Fitting
1. Inspect the inside of the quick union fitting for any foreign matter and wipe out any dirt which may
be inside. It should appear clean, shiny and bright.
2. Install the union ring-nut and push sleeve on the assembled chlorine sensor by sliding it down the
lead wire.
3. Check that the sealing O-ring is on the electrode body, on the sensing tip side of the ledge, or in the
O-ring groove of the flow cell.
4. Insert the chlorine sensor into the fitting. Rock the sensor back and forth to pass the O-ring and press
firmly all the way down so that the O-ring firmly seats in its groove.
5. By hand, turn the union-nut until finger tight. For higher pressures it may be necessary to use a
wrench; however, the components are plastic and care is needed to avoid breakage.
CAUTION: Do not use a large wrench to turn the sensor. The plastic components of the chlorine
sensor could be broken or deformed.
Removing Chlorine Sensor from Flow Fitting
1. Stop the sample flow and allow system to drain. Remove the pH sensor as per instructions on
page 33. Removing the pH sensor will reduce the vacuum effect within the flow cell.
2. By hand, turn the union-nut until free. For higher pressures it may be necessary to use a wrench to
start turning the nut.
3. Gently rock and pull the chlorine sensor back and forth to ease the O-ring seals back up the
compression throat.
4. When the chlorine sensor has been fully removed, wipe the sensor clean and then proceed to the
calibration procedure or monthly/yearly maintenance, as necessary.
Zero Test Technique
The best way to zero check at the point of use, where all water and even the air contains some chlorine,
is to use a zero chlorine solution available from AquaMetrix as P/N AM-A1100225 in a 500 mL bottle.
CAUTION: If zero standard gets on hands, wash with running water.
Protective eye-wear and gloves are suggested.
1. Pour some of the zero chlorine solution, P/N AM-A1100225, into a clean beaker.
2. Immerse the chlorine sensor into the beaker so that it is about 3 inches below the
surface of the zero check liquid; refer to illustration 23. Provide slow gentle
movement to ensure the chlorine present is consumed. The chlorine sensor
should rapidly fall below 0.1 ppm, thus confirming operation of the sensor.
Make sure that the zero check solution is used within 8 hours because the
scavenger will be used up with exposure to air by also absorbing oxygen. The
remaining zero check solution should be stored tightly capped in it's bottle. The
zero solution is “single use”, so discard the used zero solution.
CAUTION: Removal of the chlorine sensor from a sealed flow cell will vacuum stretch the thin
sensing membrane. Stretching the membrane will cause slow response and higher readings at low
levels. Parting the membrane will cause chlorine sensor failure.
Illustration 23: Zero
check