is a round spray and what is a fan spray?
spray is when the spray emitted from the nozzle forms a
round of about 15ｰ and a round shape forms when spraying
is done level. In this state, if the air that is emitted
from the pair of horns on both sides of the air cap is used
to squash the pattern, it will take on a fan shape. (The
result will be an ellipse with little distension.) This
is known as a fan spray. Moving the item being sprayed enables
a wide band pattern to be formed, making this type of spray
appropriate for covering large areas. Most spray guns have
a pattern adjustment knob for switching between round spraying
and fan spraying, while others use special caps for one
or the other that are selected from the outset. Guns with
a fan-spray cap can also be used for round spraying, thus
making a gun exclusively for roound spraying unnecessary.
Guns equipped with a cap for round spraying, however, have
the following advantages: the cap does not easily get dirty
and does not easily clog, and a sharper pattern can be obtained
for fine spraying.
In addition, when little liquid is used, the spread of
a fan spray will decrease. However, we have spray guns that
provide a wide pattern spread even when little liquid is
used (the ST-6W, HM-1W and others).
it matter whether the spray gun is mounted facing up or facing
are no restrictions on this.
For nearly all types, the piston is built in. When spraying
is stopped, the liquid will automatically be stopped. Thus,
no matter what direction the spray gun is mounted in, the
liquid will not dribble out. In addition, in terms of the
spray itself, when a long distance is involved, gravity
will cause mist particles to come down, but for usage at
a regular distance (within tens of centimeters), this phenomenon
is not pronounced.
One caution is that when spraying with the gun mounted
facing up, the mist sprayed will alight over time and the
air cap will be easily dirtied. Thus, in some cases it might
be better to mounting the gun at an angle and keep it covered,
if possible. Also, please give consideration to operational
aspects, such as how to ensure dedicated cleaning.
should the spray data in your catalog be interpreted?
spray a variety of liquids, including paint, oil, adhesives
and seasonings. Depending on viscosity, surface tension
and other factors, spray condition will also differ. However,
because of the infeasibility of preparing data on every
type of liquid used, the data in our catalog is for water
Using water as a gauge makes it possible to grasp differences
in models and differences in nozzle orifice for the same
model. In general, when liquids more viscous than water
are used, pattern spread will be narrower and particle diameter
bigger than in our catalog data, making it possible to generally
infer what the condition of the spray would be.
unit of measure is used for spray guns?
of measure for pressure used to be kgf/cm2 (kilogram force
per square centimeter). Recently, MPa (Megapascals) has
been used. Such usage is based on international agreement.
The familiar way that air pressure was referred to in weather
forecasts, for example, has been changed from millibars
to hectopascals. The pascal is used as a unit of pressure.
The conventional 1kgf/cm2 is equivalent to 0.1MPa.
Piping screw size is generally expressed in inches, such
as 1/4h (nibu) or 1/8h (ichibu).
Screws are differentiated as male or female, tapered or
straight, with letters used at the beginning of codes.
For example, a male straight screw would be indicated as
G1/4, a tapered male screw as R1/8, and a tapered female
screw as Rc1/4. ISO revision has rendered into disuse PT,
PF, PS and other indications formerly used.
should spray guns be controlled?
automatic spray guns (except for some, like the TB-2 and
HM-9) have built-in piston valves (or needle valves linked
to pistons). When air over the prescribed pressure (usually
0.3~0.4MPa) enters, the valve opens and liquid is emitted.
When the air stops, the valve is closed by spring force
and the liquid is stopped. It is sufficient to use a solenoid
valve to control airflow. No valve is necessary in the liquid
When using a gun with a piston-air separation system, please
make sure to use a three-way solenoid valve to control the
airflow for piston operation. Use of a two-way solenoid
valve would prevent the air from escaping when operations
are stopped. The air would then return to the piston, and
the liquid would not be stopped.
is the difference in how a system that separates atomized
air and piston air and a system that combines them are used?
guns share the air for atomization and piston operation
in one pipe (the ST-5, PR-20, HM-1 and others) while others
separate them (the ST-6, PR-30, HM-6, etc.).
While the shared type requires just one air pipe, they
are restricted to the minimum air pressure for piston operation
and thus cannot be used for blowing a soft mist with weak
air. (The PR-20 enables a soft mist to be blown easily with
the finger grip on the body of the gun but does not allow
In contrast, with separation systems that use two pipes
for air connection, air pressure for atomization can be
set freely, irrespective of the air for piston operation,
using an external decompression valve. Thus, when applying
oil or the like, by atomizing at a very weak pressure of
0.02~0.05MPa, a soft mist can be blown with little upward
drift. In addition, using separate solenoid valves for the
air for atomization and the air for piston operation, airflow
can be controlled with the timing staggered.
This makes fine control possible, such as only releasing
air, releasing air first and then releasing the liquid after
a slight delay, or, when stopping, stopping the liquid first.
spray guns suction up liquid?
spray guns have very slight suction, pressure would generally
need to be applied to the liquid. Applying pressure would
not necessarily mean that a pump or pressurized tank would
be needed. For other than highly viscous liquids, all that
would be needed would be to place a container (a gravity-type
container with a capacity of about 500cc to 4 liters, made
of polyethylene or the like) of the liquid either in the
same place or a slightly higher place than the spray gun.
For water, for example, for a 1m head, 0.01MPa (0.1Kgf/cm2)
of pressure is applied.
When seeking to use a large volume of a high-viscosity
liquid or when wishing to place the apparatus on the floor,
use a pressurized tank.
cautions apply to using a pressurized tank?
tank is made to feed air regulated with a decompression
valve into a sealed container of liquid and to push out
the liquid at that pressure. As it is often used when viscosity
is concentrated, the tendency is to want to raise fluid
pressure, but if fluid pressure above the necessary level
is applied, too great a volume will be emitted, thus making
it necessary to restrict volume at the mouth of the spray
gun. The spray gun's volume adjuster uses the gap between
the nozzle and the needle for adjustment. This requires
that gap to be narrowed in order to restrict the volume.
Attempting to pass a highly viscous liquid through a gap
on the order of 0.1mm will make the flow unstable. Thus,
when using a pressure-feeding tank, take care not to apply
too much fluid pressure. Although it will depend on the
viscosity of the liquid and the volume you want to emit,
this would usually be about 0.01MPa (0.1kgf/cm2) to 0.05MPa.
Leave the spray gun's liquid volume adjuster open at the
highest position. Gradually increase fluid pressure, and
fixate the decompression valve used for pressurization at
a place where slightly more than the desired fluid volume
would be emitted. Use the spray gun's liquid volume adjuster
to make fine adjustments to obtain the desired volume.
same φ0.5 nozzle is used for the ST-5 (which handles
both round and fan spraying), the ST-5R (which is for round
spraying only) and the ST-5S (which is for fine round spraying).
How do they all differ?
and ST-5R have the same body, nozzle and needle but different
air caps. The ST-5R's air cap does not have the horns for
emitting air for fan spraying that the ST-5 has. It also
does not have a knob for adjusting the air from the horns.
Because it lacks these extra protrusions, it is easy to
mount and does not take up as much space. In addition, because
the cap for fan spraying gives priority to fan-spray patterns,
it has an auxiliary air hole near the center of the cap
so that an attractive fan spray can be achieved. If this
cap is used for round spraying, the air that is emitted
through this hole will create a somewhat larger pattern;
thus, the cap specially made for round spraying enables
spraying to be done in a small, clear circle.
The ST-5S is for extra-small round patterns, and the shape
of its nozzle, needle and cap are thus different. Specifically,
the end of the needle is tapered and projects markedly from
the nozzle. If the end of the needle is bent, a sharp line
cannot be drawn; thus, a protective cover is provided.
Although a sharper pattern can be achieved if the cover
is removed, for safety's sake, please leave the cover on.
The ST-5S should be handled delicately. Unless you need
it for spraying particularly small circles or fine lines,
we recommend the ST-5R, which is ease to handle and highly
like to change the nozzle orifice. Can I do that by just replacing
to nozzles, air caps and needles also come in different
sizes to accommodate the orifice of liquid nozzles. Thus,
please replace the entire set. (The HM series contains no
needles, so please just replace the nozzle and cap.) In
addition, if a nozzle is worn and you want to replace it
with the same hole diameter, please also replace the three
aforementioned items as a set. (The fact that the nozzle
has become worn means the needle is also worn. Although
it might not be necessary to replace the air cap, please
do so if patterns seem narrower or somehow slack.)
For nearly all models, the needle is assembled to the piston.
Although the piston can be taken apart and just the needle
replaced, this is time-consuming. It is far easier to use
a piston set, in which the piston and needle have been assembled
ahead of time.
For the ST and PR series, a special wrench is necessary
to replace the nozzle. (When you purchase spray guns in
these series, the wrench will be included.) Please note
that use of a monkey wrench or the like could damage the
nozzle on its circumference, rendering it unusable.
is the best way to select a compressor?
specifies the volume of air used for 0.3MPa. The catalogs
issued by compressor manufacturers provide data on the volume
of air discharged. We recommend consulting the catalogs
of different manufacturers for details. Very broadly speaking,
it will often be the volume of air supplied at 0.3MPa. Thus,
based on this figure, please select a compressor that can
supply the volume of air for the number of spray guns you
will be using.
However, compressor efficiency may be deteriorated over
time or by air temperature. It is also necessary to consider
the loss during piping. If you select a compressor that
is too near the limit of what you require, an air shortage
might result, causing trouble. We thus strongly recommend
that you select a compressor with a higher capacity that
you actually think you need.
The aforementioned applies to continuous spray-gun operation.
If spraying is done intermittently, the compressor can store
air in the tank during breaks, which would make it possible
to get by with a compressor with horsepower lowered by that
amount. In an extreme case, even a compressor that discharges
50 L/min of air (1/2 horsepower), if the tank was completely
filled with air, it would allow a spray gun that consumed
100 L/min of air to operate for about 15 sec. Thus, if there
will be a break of several minutes until the next round
of spraying is done, a small compressor can be used in some
cases. However, if operation is done at a greater frequency
than planned at the outset, a shortage of air could prevent
atomization from occurring. Please consider this risk thoroughly
before selecting a compressor.
To repeat, trouble that results from insufficient compressor
capacity is extremely common. We thus advise avoiding making
a selection that comes too close to your minimum requirements.
do I spray a liquid that contains sediment?
that contain sediment, if that sediment precipitates inside
the gun (particularly in the nozzle) or in the piping, it
could clog, preventing the liquid from being emitted. To
prevent this, it is necessary to continue to keep the liquid
moving, even when you have stopped spraying.
In addition to placing the liquid in a container equipped
with a stirrer and providing a path for supplying the liquid
to the gun, a return path from the gun to the container
could be established and a pump used to keep the liquid
constantly circulating. Some of our spray guns also have
specifications for circulation and are equipped with an
exit for the liquid that enables it to return to a tank
when spraying is stopped. (Model nos. for such types have
a gCh at the end, such as the PR-30C).
is the difference between the PR-20 and the ST-5?
PR-20 and the ST-5 have one air pipe. They differ in that
the PR-20 has an adjuster for atomized air and can spray
easily even at low pressures. (Low-pressure spraying enables
scattering to be prevented with a coarse mist and coating
efficiency to be increased.)
However, the PR-20's low-pressure atomization differs from
the use of a decompression valve. There is no way of knowing
the pressure at which one is spraying, and fluctuations
in the pressure of input air will change mist pressure.
It should not thus be used when seeking to give spray particles
a fixed diameter. Please keep in mind that it just a simple
method of a low-pressure atomization.
In contrast, in the ST series, the ST-6 must be used for
low-pressure spraying, and it is equipped with two air pipes.
orifice is the same for the PR and ST series. How do they
PR series, body size is larger. Thus, the liquid path in
the main unit and the size of screws for piping are also
larger. As a result, even if nozzle orifice is the same,
the PR series features little liquid path resistance during
spraying and good emission of highly viscous liquids when
In comparison, for liquids of particularly high viscosity,
such as adhesives, there is also the MS-8, which has been
designed with a liquid path that is even wider than it is
in the PR series.
Can spraying be done using nitrogen gas?
gas constitutes 80% of the atmosphere, when used in the
physical state of compressed air, it essentially is no different.
However, atomizing large volumes of nitrogen gas in small
rooms will result in reduced oxygen concentration, posing
the danger of asphyxiation to workers. Please be very cautious
In addition, make sure never to use hydrogen, oxygen or
the like for atomization, as explosions or fire could result.
How heat-resistant are spray guns?
Of the materials
used in spray guns, those with low resistance to high temperatures
include O-rings, packing and grease, among others. As the
heat resistance of O-rings used in places that are in contact
with liquid to be atomized may change due to the effect
of said liquid, no generalizations can be made. Broadly
speaking, even standard spray guns can be used between 80°C
By replacing O-rings and grease with those that have high
heat resistance, it is possible to achieve heat resistance
up to 290°C. Please consult us for details.