CMX 2004 - Plumbing & HVAC

Drain Tech
Smooth jetting
Water jet drain
machines for
difficult jobs
By Warren Law
Manual or
power driven
cable drain
cleaners are used to
unblock the greatest
majority of problem
drains. However,
they are not the
most efficient in
certain situations.
High water pressure drain machines are
designed for specific applications.
Jetting machines are the most efficient
when used for blockages of grease,
soap, slime, sand and ice. Yes, ice.
Typical applications include restaurants,
fast-food outlets, and food processing
plants. Restaurants are particularly
good prospects because downtime
is lost revenue. Grease buildup is
also a health hazard and could result in
a mandated closing by health inspectors.
Other common applications include
service garages, underground parking
garages and removing sand from
excavations or drains in beach areas.
A drain cable will pierce through the
grease blockage but will only do a partial
job. The cable is not able to efficiently
clean the entire inside of the
drain due to the nature of the snake.
When the cable is withdrawn the hole
will eventually close up again, repeating
the blockage. While this ensures that the
plumber will be called back sooner
rather than later, it is not serving the
customer.
A jetter uses a different principal to
clear drains. A cable machine rotates the
cable while advancing it. The attached
cutting head works away at the blockage.
A jetter hose does not rotate. Water
pressure is variable to allow for refined
control of the hose.
Typically, the action of the nozzle
occurs at the rear of the nozzle, except
for one specifically designed nozzle. The
nozzles have a series of holes of differing
angles that push the blocking material
towards the rear, instead of pushing
it forward.
The one exception is the nozzle with
a forward hole. This is designed to
pierce a hole in the blockage to let
excess water pass through. It is also
extremely practical for cutting into
frozen drains.
While a cable machine cleans when
the cable advances, a jetter does exactly
the opposite. The hose is pushed down
the drain as far as possible then pulled
back a few feet at a time. During this
pull-back the rear-jet nozzles clean the
drain, then it is advanced again and
pulled back again.
Randy Woodruff, left, and Troy Biard of Braywood Mechanical Services, Newmarket, Ont., bleed air from the water jet hose
prior to beginning work. The gas powered machine will remain outdoors.
Excess water
An inherent problem with jetters is the
excess water being introduced into the
drain during the unblocking process. All
manufacturers’ machines on the market,
except one, are similar. The one exception
has a pump mounted on the unit.
However, the problem is really not as
serious as it sounds. In some cases the
surroundings are already flooded due to
the blocked drain. A little more water is
not a big problem.
A shop vacuum or other sort of
pump can be used to collect the excess
water being pushed back towards the
drain entry until the drain is beginning
to be unblocked, letting the water flow
forward. In any case, the most common
electric powered jetters use 1.7 gallons
per minute of flow. A good length of
drain can be unblocked in a short time.
Heated water
Most jetters are designed to use water
heated to 140°F or, in other words, the
normally heated water temperature of a
household. Hotter water may damage
the pump cylinders and rings. However,
most jetters have an integrated thermal
relief valve for protection. If hot water is
used, or if the motor is left running but
the water is not circulating, it will
release water from the pump. This action
allows cold water to enter the
pump, therefore preventing any possible
damage. This is a good thing, but
requires attention on the job because it
releases onto the floor if you do not put
a bucket under it.
Jetters also have a vibration action
built-in. Jet hoses will advance slowly by
themselves with the pushing action of
the rear-jetted water. But they do not
advance automatically. Because of this
and the weight of the hose and water
inside, plus the friction of the hose
material, a lot of resistance occurs
inside the drain.
A rough material drain, such as cast
iron, can be especially resistant. The
vibration action takes the weight of the
hose off the bottom surface of the drain
because it is vibrating in the air half the
time. Try advancing or retrieving a hose
with the vibration activated. Then try it
with the vibration off just to see the difference.
So far we have spoken mainly about
electric jetters. Almost all electric jetters
from any one manufacturer are identical
in that they produce about 1,500 psi,
1.7 gpm and use 1 1/2 hp motors. Some
use triplex pumps.
Cleaning the jet nozzle is another critical
first step. Latex gloves are durable
and disposable.
The differences in these machines are
simply in the way they are put together.
You can purchase models without
accessory holders, with or without
wheels or models where the hose reel is
above the motor/pump or below it.
Price differences are accounted for by
the length, diameter of hoses and selection
of nozzles. But the basic machine is
interchangeable.
Gas powered jetters
Larger jetters are powered by gasoline
engines. Here there is more variety
because models can vary in pressure,
engine power, gpm, etc. The efficiency
of a unit is the result of the combination
of all three. A 16 hp, 3,000 psi/5.5 gpm
machine is much more efficient that an
11 hp, 2,000 psi/three gpm unit.
Current regulations do not allow the
use of a gas engine inside a building, so
gas powered jetters are mostly restricted
to outside use. Some models can be
operated inside with the use of a hose
chariot incorporating controls on the
handle. The gas unit is outside but the
operation is inside. These units
absolutely require two men to operate
for obvious safety reasons.
Small trailer-mounted units come
with a 200-gallon water-holding tank.
An example is one that uses a 24 hp
engine with electric start. This powers a
2,500 psi, 12 gpm pump through a twoto-one
V-belt reducer.
Use the right nozzle
The nozzle is a key element in determining
how well a jetter works. Among
some drain technicians, the impression
is that a nozzle is a nozzle. But they do
differ.
Each machine comes with an assortment
of nozzles. Each nozzle is designed
for a particular machine. And within
that one machine, each nozzle is designed
for each size of hose being used and
for the type of blockage as well as the
diameter of the blocked drain.
16 Plumbing & HVAC Product News – March/April 2004 www.plumbingandhvac.ca