6 308–293
Selection
Charts
CHART 3: OPTIONAL ORIFICE PURGESST NEEDLE 
Optional
Stainless
Steel
Orifice-Purge
Needle Part No.
Orifice Size
186–931 0.042”
(1.067 mm)
186–932
0.055” (1.397 mm)
186–933
0.070” (1.778 mm)
186–934
0.086” (2.184 mm)


Use

these needles to purge fluid out of the nozzle

orifice to prevent plugging of the tip with fast drying

material. A needle shaft assembly (part no.

224–849) must be used with these needles and

replaces the standard one-piece needles.

CHART 4: NEEDLE ASSEMBLYREPLACEMENT TIPS
Needle
Assembly
Part No.
Needle T
ip P/N
238–217 191–016
238–218 191–017
238–219 191–018
238–703 191–564
Selecting the Proper Needle/Nozzle/AirCap Set
The
High V
olume Low Pressure Spray Gun’
s needle/
nozzle sets range in size to provide dif
ferent fluid flow
rates. Chart 1 shows the recommended combinations
based on fluid viscosities and flow rates.
As a general guideline, use the fluid nozzle that will
give the required flow with the needle fully triggered at
the lowest fluid pressure.
For low flow rates or light viscosity fluid, select the
smaller nozzle sizes.
For high flow rates or high viscosity fluid, select the
larger nozzle sizes.
Using an air cap size that is smaller than the nozzle/
needle size is not recommended.
NOTE: T
o help select the proper needle/nozzle size, a
fluid pressure gauge may be connected temporarily to
the gun fluid inlet to determine the fluid pressure. See
Accessories.
Selection Problems and Solutions
PROBLEM POSSIBLE
CAUSE SOLUTION
Fluid pressure is
too
high (greater than
10 psi [70 kPa, 0.7
bar]) with gun trig
-
gered
Using set with
too small orifice
Use needle/
nozzle/air cap
set with larger
orifice
Using a low pres
-
sure setting, the
fluid flow
is too high,
making it necessary
to restrict needle
travel to reduce fluid
flow.
Using set with
too large orifice
Use needle/
nozzle/air cap
set with small
-
er orifice
Fluid system will not
operate at low
enough fluid pres
-
sure [below 10 psi
(70 kPa, 0.7 bar)]
There’
s no fluid
regulator or air
regulator is not
sensitive
enough
Add low pres
-
sure fluid regu
-
lator or add
more sensitive
air regulator on
pressure pot