Insert containers. Insert containers are pail-like metal vessels designed to sit inside the tank. This
eliminates cleaning the tank and facilitates the rapid change from one color to another. Their use permits several batches
of material or colors to be mixed ahead of time. This construction also permits feeding directly from small cans of paint
instead of from the full-sized container inside of the tank.
Agitators. Certain materials require constant or frequent agitation while in the tank, and to meet this
requirement, tanks are frequently supplied with mechanical agitators which can be activated by an air motor, by an electric
drive, or by a manual crank.
General. Most metal containers are rugged, substantially built. and should present few, if any,
operating difficulties. If regulator-type tanks are properly adjusted, air vents are kept free, and agitators are used when
needed, little maintenance will be required beyond thorough and adequate cleaning procedures. Mounting a tank upon a
dolly greatly extends the working area when used for multiple-gun operation. Tanks are available which provide for
simultaneous two-gun operation.
Precautions. Observing the following precautions will insure the proper operation of material
Never remove the cover from a pressure-feed container unless the pressure has
Clean thoroughly after use, as many spray gun malfunctions can be traced to improper cleaning of the material container;
be sure the fluid and air valve connections on the container are the proper size for the hose being used; test the tank
safety valve regularly; keep the material containers full, as they do not function efficiently "I-' when nearly empty; and use
the agitator regularly (where paint is being applied very rapidly, agitators are seldom needed, yet failure to agitate certain
materials results in the formation of a surface skin which rapidly clogs filters and hose).
Construction. Two types of hoses are used with spray guns: and fluid. An air hose has a red or orange
cover while a fluid hose is black. The inner tube of a fluid hose is constructed of a solvent-resisting material that is
generally impervious to any of the common solvents used in paint.
Size. Hose of adequate inside diameter must be used with all spray gun systems. Too often a spray gun is
blamed for improper paint feeding, or a material is considered of inferior quality, when the real cause of the trouble is low
air pressure at the spray gun. Usually, this condition is caused by a hose that is too small. As seen in table 5-1, there is a
natural pressure drop whenever compressed air is transmitted, and the amount of this pressure drop increases as the
hose gets smaller.
Pressure drop. Table 5-1 shows the air pressure drop expected from various lengths of one-fourth and five-
sixteenths inch hose when used with a spray gun. For example, with 70 pounds of air pressure at the transformer, only
47 and one-half pounds of pressure (70 minus 22.5) will exist at the spray gun when 25 feet of one-fourth inch hose is
used to connect the two units.
Cleaning. The fluid hose should be cleaned immediately after use. In no event should a fluid hose be left
Storage. When not in use, the hose must be coiled and hung where it will be free from possible damage.