TERMINOLOGY

A spraygun may have a cup, to contain the material that you are spraying, either above the gun (gravity fed), below the gun (suction or siphon fed), or it may not have a cup at all, but be fed remotely from a separate pot which is under pressure. (or a low pressure pump)
Some of the features and benefits of each are described below.

GRAVITY FED.
The cup is above the gun, and the material falls into the gun by gravity.
ADVANTAGE. The cup is usually nylon, or similar, and is fairly lightweight.
Because the cup is also usually transparent, the material level is always visible
in the cup (can be refilled before it runs out).
Uses slightly less air in general than suction fed.

NOTE. When material is in cup, the gun needs either to be held in a stand, or suspended.

SUCTION FED.
Also known as syphon fed. The cup is below the gun and material is siphoned out of it.
ADVANTAGE. Only that the cup has a flat base and can stand up on a flat surface
 (though still difficult with hose attached).

NOTE. Difficult to judge how much material is left in cup. Uses more air than gravity fed.

PRESSURE FED. Air is connected to a remote pressure pot, into which the product is poured.
Some of the air goes into the pot and forces the material out under pressure. The pot has an air hose,
and a fluid hose linked to the spraygun that it is feeding.
ADVANTAGE. Much more material can be applied before refilling. Faster coverage.
Also handles thicker materials better. Good for mass production on one colour.

NOTE. Notoriously difficult to clean out thoroughly, or colour change.
Because the material flows faster, more air is required to atomise it, so uses more air
than suction or gravity.

OTHER TERMS USED
TRANSFER EFFICIENCY. How much of the product that originally went into the cup,
actually ends up on the surface that you are trying to spray. It is expressed as a percentage.

CONVENTIONAL SPRAYGUNS.
Mini, general purpose, and pressure fed sprayguns are all available as conventional.
This means that they are passing air, at the input pressure, straight through the gun.
The result is that the material leaves the gun at high velocity, usually resulting in a lot
of overspray, as much of the material actually bounces back off the surface being sprayed.
The transfer efficiency is likely to be around 50%.

H.V.L.P. SPRAYGUNS.
Abbreviation of high volume, low pressure.
Can again be mini, general or pressure fed. In H.V.L.P. the air pressure and volume is
changed within the gun, so that there is ultimately much less pressure at the nozzle,
so less velocity and less rebound.
A genuine H.V.L.P. gun will transfer 65%, or more if used correctly.
Can use slightly more air volume than conventional, (old models of H.V.L.P consume much more),
and the handling of the gun can change slightly as well.

If you use large amounts of solvent bourne product, you may have to use H.V.L.P
or compliant gun (see below).
Your paint supplier will advise on this.

COMPLIANT SPRAYGUNS. (E.P.A. COMPLIANT).
These are conventional sprayguns, which if used correctly, will transfer 65% or more of the product.
They are usually certified to state this.

Please note that the information given is intended as a guideline only.
Though most of the equipment mentioned will cover most applications, there still may be a better
method for your application.
AGAIN. ASK ADVICE IF IN DOUBT.
You can think of a spraygun in general, a little like a paintbrush.
The bigger it is, the larger an area it will cover. The thicker it is, like a bigger nozzle size,
the heavier the coverage. If you build too quickly it results in runs, too thinly, and more coats are required.
Preparation is critical to the resulting finish, and the equipment MUST be properly cleaned afterwards
if you wish it to perform again next time. You also tend to “get what you pay for”.

Remember, a skilled sprayer, like a brush painter did not start yesterday. Only experience will develop skill.

RAND EQUIPMENT OFFER A WIDE RANGE OF SPRAY EQUIPMENT TO COVER MOST
OF THE GENERAL SPRAYING REQUIREMENTS.

Also available are quick release air couplings, air hoses, fluid hoses,
air filtration and regulation equipment, dryers, breathing equipment, hobbyist spraykits
and of course the air compressor to suite.

FOR THE PROFESSIONAL USER, WE ALSO OFFER A COMPREHENSIVE RANGE
OF SPRAYGUN CLEANING MACHINES.