Underground Construction - October 2017 - 57

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choose the right nozzle design
for particular tasks. factors
to consider include the number,
direction, and angle of jet streams,
the type and material of jets (and
whether they're replaceable), and
the construction and material
quality of nozzles.

The main reason to choose the proper nozzle for
cleaning a section of sewer is to enable the operator
to efficiently clean and remove the material that is in
the sewer. Choosing a good set of quality nozzles for
your equipment and deploying the right nozzle when
actually cleaning sewers is the best way to take full
advantage of big investments in jetting equipment
and to clean sewers efficiently while reducing labor
costs, wear and tear on equipment, and fuel use.
Proper nozzle selection will increase the efficiency of
the cleaning operation. The wrong nozzle may not
remove the material completely.
The sewer should be inspected before cleaning to
determine the type and amount of material to be
removed. This will help determine the correct nozzle.
Factors to consider include: type of material (loose,
attached, large, small), size of pipe, pipe material,
length of section, slope of pipe. The decision to
use nozzles, chain knockers, and other mechanical
means must consider structural defects in the pipe.
Nozzles are designed for particular types of material
removal and selecting the wrong nozzle can either
prolong the job or not remove the material.
Choose the right nozzle design for particular tasks.
Factors to consider include the number, direction, and
angle of jet streams, the type and material of jets (and
whether they're replaceable), and the construction
and material quality of nozzles. Low degree jets
(jetting angles more in line with pipes) on a nozzle will
move loose material quickly, and thrust it longer
and farther up the line (this is also good for breaking
blockages). Depending on the size of the line, lower

October 2017 Underground Construction

angle jets may remove debris differently depending
on how the nozzle sits in the pipe. Wide-angle jets
(more perpendicular to pipes) will clean the walls of a
pipe but do not do an excellent job of moving loose
material, and have less thrusting power.
Choosing the right nozzle, and investing in higher
quality nozzles pays off with dramatically increased
productivity (up to 100%), and better nozzles also
tend to last longer, feature internal parts that
can be replaced, require less maintenance, and
generally provide significant return on investment
over long lifespans.
With any nozzle, it is important that the nozzle is
properly set up for the flusher with which the nozzle
will be used. The jets on the nozzle need to be
sized for the amount of actual flow at the end of the
hose for the particular vehicle. This can be done by
the nozzle supplier or in house. The wrong jets will
decrease the efficiency of any nozzle.
Cutters are another option for cleaning sewers.
The sewer should be free of all loose debris prior
to using a cutter. The loose debris will slow down
the cutter, make it less efficient and increase
the time and effort necessary to complete the
cleaning process.
The choice of a nozzle should not be taken lightly
and the days of "my favorite nozzle" are in the past.
A good operator is properly trained in the use of
different nozzles and uses the correct nozzle at
all times.

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Underground Construction - October 2017

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