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DESCRIPTION:

The A-AU Automatic Spray Gun, is a light duty air actuated 

production spray gun. It will cover a range of materials to include 

light lacquers, latex, acid or corrosives. 

When using Extensions, 

material must be pressure fed for proper application.

CONNECTIONS:

Connections to the gun are:  Air Inlet 1/4” N.P.T. (F) and Fluid 

Inlet 1/4” N.P.T. (M).  A-AU Automatic Spray Gun  dimensions 

are: 5-1/8” (L) x 2-1/4” (D).  Packings and piston are PTFE.

Spray Heads for the A-AU Automatic Spray Guns are available 

in several different styles, some of which are available with 

Stainless Steel components.  The C.F.M. requirements 

range from .25 to 3 C.F.M. @ 30 lbs. air pressure.  NOTE:  

When either fluid Tip or fluid Needle is worn and requires 

replacement, it is recommended that both items be changed 

for best results.  

All Tips and Needles are made using 303 Stainless Steel.

OPERATION:

1. Mount Gun in desired position

2.  Before installing, blow out air hoses with compressed air to 

remove foreign particles.

3. Connect hose from air supply to air inlet fitting.

4. Connect fluid hose to fluid inlet supply.

5. Tighten all hose connections securely.

6. Adjust air pressure to 45-55 P.S.I. at the Air Regulator.

7.  Adjust  fluid  volume  by  turning  the  U-3178  Fluid  Adjusting 

Knob to the left or right.

NOTE:  DO NOT USE U-3178 AS A SHUT-OFF BY TURNING 

ALL THE WAY DOWN - IT MAY SPLIT THE TIP.

TIP REMOVAL:

1. Turn off Air and Fluid Pressure.

2.  Release Needle pressure from the seat of Tip, by backing 

off the U-3178 Fluid Adjusting Knob approximately 5 turns, 

then removing U-2686A Cylinder Cap Assembly.

3.  

Loosen AU-12 Aircap Nut and remove Spray Head 

Assembly. 

Leave Needle In Place.

4. Unscrew AU-Tip.  Place New AU-Tip in position.

5. To replace, reverse above procedure.

A-AU

Automatic Spray Gun

OPERATING INSTRUCTIONS AND REPLACEMENT PARTS

INSTRUCTIONS & PARTS LIST A-AU 1/25/2018

Paasche Airbrush Company

4311 North Normandy Avenue

Chicago, IL 60634-1395

Phone:

  773-867-9191 

  

Fax:

  773-867-9198

Website:  paascheairbrush.com

E-Mail:  info@paascheairbrush.com

WARNING:

  Spray materials may be harmful if inhaled or 

allowed to come into contact with the skin or eyes. Consult 

the product label and Material Safety Data Sheet supplied 

for the spray material. Follow all safety precautions. 

CAUTION:

  Well Ventilated Area Required to remove 

fumes, dust or overspray. Secure airhose and fluid 

hose wrench tight for safety and to prevent leaks.

M a x i m u m   A i r   P r e s s u r e   1 0 0   P . S . I .

M a x i m u m   F l u i d   P r e s s u r e   4 5   P . S . I .

MAINTENANCE:

Requirements of the A-AU Automatic Spray Gun have been 

reduced to a minimum.  The leather packing washers should be 

lubricated once a month with a light oil.  Old Packing Washers 

cause leakage of Air or Fluid and replacement should be made. 

PTFE Packings are self-lubricating. Flush clean solvent through 

the Fluid passages of the Spray Gun and Wipe off the outside 

with clean solvent.  Never leave the entire Spray Gun immersed 

in solvent.  Dirty Aircaps and Tips should be cleaned by soaking 

in solvent and blown clean with air.

 

CLEANING:

TROUBLE SHOOTING SPRAY PATTERNS:

(A) 

 A ROUGH OR STIPPLE FINISH

 is due to low or restricted flow of air 

pressure or too heavy materials being applied with spray gun too close 

to surface.

(B) 

 A WET OR SAGGING FINISH

 is due to low air pressure or restricted 

flow of air, material being too thin, applied too close to the surface.

(C)  

A SPUTTERING SPRAY

 is caused by air leaking into fluid line or can 

be caused by a loose fluid tip, a broken or split tip, lumpy material, 

a clogged vent hole in cover of material cup,  air leak at fluid pipe 

attached to inside of tank cover, or a clogged paint strainer.

 

 TO  CORRECT:

 Tighten tip securely or replace.  Strain materials 

and clean strainer. Sputtering might also be caused by worn packing 

washers, or worn or scored  needle.

(D) 

 AN ARCHED FAN SPRAY PATTERN

 is caused by dried material 

accumulated in one fan port of the fan aircap distorting the pattern.

 

 TO  CORRECT

: Dissolve material inside fan port with suitable solvent 

applied with a small brush.

 

 NOTE:  Never use wire or sharp instruments to clean fan ports 

as permanent damage to the air ports will result in destroying 

uniformity of the fan pattern.

(E)  

UNBALANCED FAN SPRAY PATTERN

, heavy on one side, may 

be caused by material collecting around outside of the fluid tip and 

aircap, or by a loose aircap.

 

 TO  CORRECT: 

Remove  aircap  and  clean  fluid  tip  and  aircap  with 

solvent, dry with air pressure.  Always be sure fan aircap and aircap 

body is tightened securely.

(F)  

A HEAVY CENTER

  in  a  fan  pattern  is  caused  by   insufficient  air 

pressure at the fan port.  Rough or shady edges are also caused by 

low air pressure.

 

TO CORRECT: 

Increase air line pressure.

(G) 

 A SPLIT FAN SPRAY PATTERN 

heavy on each end and light in the 

center, is caused by excessive air pressure.

 

TO CORRECT: 

Reduce air pressure.

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