Chlorination of water is a standard method of insuring a
safe supply of water. Chlorine residuals in the water kill harmful bacteria
that may be present. Chlorine can also be used to reduce sulfur odor problems
with some types of water sources. A sodium hypochlorite (bleach) chlorination
system is common, and its parts include a contacting-head water meter which
sends signals to a chemical metering pump to proportionally inject the chemical
based on the water flow rate in the pipe. Injection does not occur unless there
is water flow. To obtain a low, but steady chlorine residual, a liquid system
is optimal. The range of acceptable free chlorine levels is 0.3 to 0.5 parts
per million, delivered at the most distal part of the water system.
1
Purchase a contacting-head water meter -- in-line or insertion style --
and a chemical metering pump that fits the size of the water main and its flow.
The type of water meter you need is determined by the size of the pipe. In-line
water meters are commonly available for water pipes that are from 3/4 to 2
inches in diameter. If your water supply pipe is larger, then you must purchase
an insertion meter that is installed on a saddle fitting, which is cemented and
fastened over a hole drilled in the pipe.
2
Turn off the water pump and shut off valves that are above and below the
point of installation of the in-line water meter. Drain the water out. Cut the
pipe where the water meter is to be installed. Clean the cut pipe of any PVC
pieces with a knife. Glue on the PVC fittings to the line that provide female
threads for connecting the male fittings of the water meter. Install the water
meter male threads on each side of the pipe and then connect the unions (which
come with the water meter) to the water meter body. If you are installing an
insertion meter, drill the appropriate size hole at the insertion site and
install a saddle fitting over it. If the saddle fitting has a hole which is too
large for the meter threads, then install reducer bushings as needed.
3
Screw in the insertion flow meter. You will also need to make a hole for
the chlorine injection downstream of the meter and install a saddle fitting. An
injection fitting usually has 1/2-inch male threads, so you need to have a
1/2-inch female fitting to receive it.
4
Mount the chemical metering pump in a location above the bucket used for
holding the sodium hypochlorite. Drill the mount holes and fasten the pump to
the mount. On the injection side, connect the injector fitting and screw in
into the site of injection on the pipe. On the suction side, install the foot
valve so it reaches the bottom of the chemical container.
5
Plunger pump and prime it with bleach solution. In order to prime this
type of pump, turn it on so it is at full capacity and speed and open the valve
for priming which is on top of the pump. If you do not have a priming valve,
you may have to grab the tubing and move it up and down to make the liquid move
up the tubing and get to the pump head. Disconnecting the tubing above the head
also helps priming. Once you see the liquid rising above the head in the tubing
above, the pump is primed and ready for injection in the water system.
6
Keep the pump running until the bleach solution reaches the injector
fitting; adjust the pump back to the setting for the calculated injection rate.
Then unplug it. Finally, install the water meter contact cable to the pump.
7
Check to make sure all fittings do not leak; then plug in the pump for
chlorine injection. Allow the system to pump for an hour or more while there is
water use at the most distal point. Test the free chlorine residuals at this
point to see if they are at 0.5 to 1 parts per million. Adjust the pump
settings and the bleach concentration levels to help achieve the appropriate
free chlorine residuals.
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