DeVilbiss SB-2-001-F Troubleshooting And Maintenance Manual
SPRAY GUN TROUBLESHOOTING AND
PREVENTIVE MAINTENANCE GUIDE
SERVICE BULLETIN
SB-2-001-F
Replaces SB-2-001-E
IMPORTANT: Before using this equipment, read all
safety precautions and instructions in this manual.
Keep for future use.
Page 2 SB-2-001-F
SAFETY PRECAUTIONS
This manual contains information that is improtant for you to know and understand. This information relates
to USER SAFETY and PREVENTING EQUIPMENT PROBLEMS. To help you recognize this information, we
use the following symbols. Please pay particular attention to these sections.
Note
Important safety information A hazard that may cause
serious injury or loss of life.
Important information that tells
how to prevent damage to equipment, or how to avoid a situation
that may cause minor inury.
Information that you should
pay special attention to.
The following hazards may occur during the normal use of this equipment. Please read the following chart before using this equipment.
HAZARD CAUSE SAFEGUARDS
Fire Solvent and coatings can be highly Adequate exhaust must be provided to keep air
flammable or combustible free of accumulations of flammable vapors.
especially when sprayed.
Smoking must never be allowed in the spray area.
Fire extinguishing equipment must be present
in the spray area.
Solvent Spray During cleaning and flushing, Wear eye protection.
solvents can be forcefully expelled
from fluid fluid and air passages.
Some solvents can cause eye
injury.
Inhaling Toxic Certain materials may be harmful Follow the requirements of the Material Safety
Substances if inhaled, or if there is contact Data Sheet supplied by your coating material
with the skin. manufacturer.
Adequate exhaust must be provided to keep the
air free of accumulations of toxic materials.
Use a mask or respirator whenever there is a
chance of inhaling sprayed materials. The mask
must be compatible with the material being
sprayed and its concentration. Equipment must
be as prescribed by an industrial hygienst or
safety expert, and be NIOSH approved.
Explosion Hazard Halogenated hydrocarbon solvents Guns with stainless steel internal passageways
Incompatible - for example; methylene chloride may be used with these solvents. However,
Materials and 1, 1, 1 - Trichloroethane are aluminum is widely used in other spray
not chemically compatible with application equipment - such as material pumps,
the aluminum that might be used cups and regulators, valves, etc. Check all
in many system components. The equipment items before use and make sure
chemical reaction caused by these they can also be ued safely with these solvents.
solvents reacting with aluminum Read the label or data sheet for the material
can become violent and lead to an you intend to spray. If in doubt as to whether
equipment explosion. or not a coating or cleaning material is com-
patible, contact your material supplier.
SB-2-001-F Page 3
PRINCIPLES OF AIR SPRAY
Spray application is perhaps the simplest method of
coating where a sizeable area or volume of material
is involved or when intricate shapes and irregular
surfaces require painting. Spray will give the most
uniform film thickness making it easy to obtain a
smooth finish.
The air spray gun is a tool which uses compressed
air to atomize paint, or other sprayable material, and
to apply it to a surface. Air and material enter the
gun through separate passages, and are mixed at
the air cap in a controlled pattern. Air spray guns
may be classified in various ways. Two ways of
classifying guns are by the location of the material
container and the material feed system. Figure 1
shows a gun with a cup attached below. This is
called Suction Feed which draws material to the
gun by suction. Figure 3 is a gun with a cup attached
above. This is called Gravity Feed - the material
travels down, carried by gravity. Figure 4 shows a
material container some distance away from the
spray gun. This is Pressure Feed - the material is
fed by positive pressure. Suction feed is easily
identified by the fluid tip extending slightly beyond
the face of the air cap, as shown in Figure 2. Suction
feed guns are suited to many color changes and to
small amounts of material, such as in touchup or
lower production operations.
Figure 3 Gravity Feed Gun With Cup on Top
Gravity feed guns are ideal for small applications
such as spot repair, detail finishing or for finishing in
a limited space. They require less air than a suction
feed gun and usually have less overspray.
Figure 1 Suction Feed Gun with Attached Cup
Fluid
Tip
Figure 2 Suction Feed Air Cap
Figure 4 Typical Pressure Feed Gun With Remote
Cup
Fluid
Tip
Air Cap
Air Cap
Figure 5 Pressure Feed Air Cap
A pressure feed system is normally used when large
quantities of material are to be applied, when the
material is too heavy to be siphoned from a container
or when fast application is required.
Page 4 SB-2-001-F
Internal and External Mix Guns
An external mix gun mixes and atomizes air and fluid
outside the air cap. It can be used for applying all
types of materials, and it is particularly desirable
when spraying fast-drying paints such as lacquer. It
is also used when a high quality finish is desired.
Figure 6 External Mix Gun
Figure 7 Internal Mix Gun
This gun mixes air and material inside the air cap,
before expelling them. It is normally used where low
air pressures and volumes are available, or where
slow-drying materials are being sprayed. A typical
example is spraying flat wall paint, or outside house
paint, with a small compressor. Internal mix guns
are rarely used for finishing when a fast-drying
material is being sprayed, or when a high quality
finish is required.
HVLP (High-Volume/Low-Pressure)
HVLP uses a high volume of air (typically between
15-22 CFM) delivered at low pressure (10 psi or
less) to atomize paint into a soft, low-velocity spray
pattern.
Conventional
HVLP
Figure 8 Air Cap Overspray, Conventional/HVLP
The HVLP spray gun resembles a standard spray gun
in shape and operation.
HVLP is growing in popularity and it has also been
judged environmentally acceptable due to its high
transfer efficiency.
HVLP can be used with low to-medium solid materials, including two-component paints, urethanes,
acrylics, epoxies, enamels, lacquers, stains, primers, etc. More recently developed HVLP air caps can
also satisfactorily atomize even high solid coatings.
OPERATION
Suction and Gravity Feed Equipment Hook-Up
Connect the air supply from the compressor outlet
to the air filter regulator inlet. Connect the air
supply hose from the regulator outlet to the air inlet
on the spray gun. After the material has been
reduced to proper consistency, thoroughly mixed
and strained into the cup, attach the gun to the cup.
As a result, far less material is lost in overspray,
bounce-back than with conventional air spray. This
is why HVLP delivers a dramatically higher transfer
efficiency (the amount of material that is actually
applied to the part) than higher pressure spray
systems.
Figure 9 Suction Feed & Gravity Feed System
Components
Spray a horizontal test pattern (air cap horns in a
vertical position). Hold the trigger open until the
paint begins to run. There should be even distribution of the paint across the full width of the pattern
(see Figure 11). Adjust with fan pattern adjustment.
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