II. INSTALLATION
Refer to Figure 3 for this section.
1. Sample Water Connection and Control: The following are some considerations relating to the
sample water supply. The WQM-100 Water Quality Monitor requires a constant supply of sample water
at a controlled rate and pressure. Precautions should also be taken to ensure that the sample water
reaching the measurement cell is not altered as it passes through the sample water piping. Also, the
connection to the sample point should be made in such a way to avoid receiving air or sediment from
the pipe. Consider fi gure 4 when creating your sample water line
Flow: The sample water fl ow rate should be controlled at an ideal rate of 500 ml/minute (8 GPH).
A fl ow meter and rate control valve may be necessary to achieve and maintain this fl ow rate. This
can be installed upstream from the measurement cell.
Pressure: Where the sample point has a water pressure higher than 87 PSI (6 bar), a pressure-
reducing valve must be employed to deliver the sample water to the measurement cell. The sample
water entering the measurement cell should be at a pressure below 87 PSI (6 bar). If the sample
point pressure is too low, then it may be necessary to use a sample pump to deliver the sample water
to the measurement cell.
Other Considerations: It should be considered, that any biological growth inside the sample piping
system will have some adverse eff ects. This can cause the sample water reaching the measurement
cell to not be an accurate sample. For example, the ORP could change as the sample water passes
through the sample water piping system. For this reason, it may be necessary to periodically clean
the sample water piping system to prevent any biological growth or clear out residual chemical
buildup. Also, it is generally not recommended to use a fi lter in this piping system because as the fi lter
collects particles it can lead to inaccurate readings. However, in certain installations with signifi cant
amounts of solids in the sample water (particularly iron and manganese) the use of sample water
fi lters may be necessary.
2. Sample Water Disposal Considerations: If no reagent and/or pH buff er chemical is being
injected, then the disposal of the water departing the measurement cell is usually not a signifi cant
concern. However, if some reagent and/or pH buff er chemicals are being injected, then all applicable
regulations should be considered before making the decision of how and where to dispose of
the wastewater exiting the measurement cell. Refer to the MSDS of the chemical in question for
instructions on proper disposal.
3. Sample Point Selection:
There are at least two general concepts to consider when selecting the sample point location. First,
is to select a point that allows reliable determination of the parameter to be measured at the most
critical point for the particular installation. Second, is to take into consideration any chemical injection
control timing. A balance between these considerations must be reached.
Each system is unique, however in general the goal of the chemical injection is to achieve some result
by maintaining a certain measurement at a particular point in the system. For example, to maintain
a specifi c chlorine residual at the exit of the drinking water facility. The location should be selected
so that the injected chemical is already fully mixed so that an accurate sample can be sent to the
measurement cell.
WARNING! Do not run the instrument without sample water running through it. Lack
of, or interruption of water fl ow can cause premature failure of the electrodes.
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