DeVilbiss HVLP Gravity Feed Spraygun Spécifications télécharger pdf (Page 5)

5. What is a pressure feed gun?

In this design, the fluid tip is flush

with the face of the air cap (see

Figure 5). The material is

pressurized in a separate cup, tank

or pump. The pressure forces the

material through the fluid tip and to

the air cap for atomization.

Figure 4 - Typical Pressure Feed

Gun with remote pot

This 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. Production spraying in

a manufacturing plant is a typical

use of a pressure feed system.

Figure 5 - Pressure Feed Air Cap

Table 1

6. What is an external mix air

cap?

This 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

7. What is an internal mix cap?

This cap 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 caps are rarely used

for finishing when a fast-drying

material is being sprayed, or when

a high quality finish is required.

Figure 7 - Internal Mix Air Cap

8. What is HVLP?

HVLP, or High-Volume/Low

Pressure, uses a high volume of air

(typically between 10-26 CFM)

delivered at low pressure (10 PSI or

less at the air cap) to atomize paint

into a soft, low-velocity pattern of

particles.

In many cases, less than 10 psi is

needed in order to atomize.

Proper setup utilizes no more fluid

and air pressure than is needed to

produce the required quality and a

flow rate that will meet production

requirements.

As a result, far less material is lost

in overspray, bounceback and

blowback than with conventional

air spray. This is why HVLP delivers

a dramatically higher transfer

efficiency (the amount of paint that

adheres to the substrate compared

to the amount of paint sprayed)

than spray systems using a higher

atomizing pressure.

The HVLP spray gun resembles a

standard spray gun in shape and

operation. Models that use high

inlet pressure (20-80 psi) and

convert to low pressure internally

within the spray gun are called

HVLP conversion guns.

Some HVLP models, particularly

those using turbines to generate

air, bleed air continuously to

minimize back-pressure against

the air flow of the turbine.

The air cap design is similar to that

of a standard spray gun, with a

variety of air jets directing the

atomizing air into the fluid stream,

atomizing it as it leaves the tip.

HVLP is growing in popularity and

new environmental regulations are

requiring it for many applications.

HVLP can be used with a wide

variety of materials, including

two-component paints, urethanes,

acrylics, epoxies, enamels,

lacquers, stains, primers, etc.

2. Air Atomizing Spray Guns (Cont’d)

5

A DeVilbiss Pro Tip:

When using a gravity feed system,

downsize the tip one size from suction.

If the suction system calls for a .070",

use a .055" or .063"

Type Viscosity Fluid Atomizing Type

Feed (#2 Zahn) Oz/Minute Pressure Production

Suction up to 24 10-12 40-50 Low

Gravity up to 24 10-12 30-50 Low

Pressure up to 29 30-Oct 50-60 High

HVLP up to 29 14-16 10 High

1 2 3 4 5 6 7 8 9 10 ... 29 30

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